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High abundance and low toxicity make zinc oxide very attractive for broad application in the field of photocatalysis for remediation of toxic compounds from water. Its performance could be elegantly improved by inducing native defects into ZnO semiconductor nanocrystals. However, this typically requires post-processing at high temperatures, during which many of the benefits of the original batch of monodisperse small grains are lost due to agglomeration and/or crystal growth. Within this research we show how variations in defect population are inherent to recrystallization process and that they can be tuned to some extent by choosing optimal pathways. The defects were studied by Raman, photoluminescence and EPR spectroscopy, while the surface chemistry of the ZnO nanorods, solvothermally recrystallized from ZnO nanodots, was evaluated by X-ray photoelectron spectroscopy. The produced nanorods with different dimensions were also utilized to show how effective the samples are for degradation of a model pollutant, namely caffeine. Unexpectedly, we found that the surface chemistry of our samples is not the main factor in photocatalytic efficiency. Instead, we show that the differences in photocatalytic activity are mainly determined by the defect population within the bulk formed during the recrystallization process under altered solvothermal conditions. [ABSTRACT FROM AUTHOR]

The introduction of oxygen defects in semiconductor electronic structures is considered to be an effective strategy to improve their photocatalytic activity. In this work, rare-earth Er3+−doped BiOBr (Er/BiOBr) with oxygen-rich vacancies (OVs) was prepared via simple hydrothermal method. Compared with pure BiOBr, Er/BiOBr has a narrower band gap and more abundant OVs, which together improve the separation efficiency of photogenerated carriers. The introduction of Er not only creates impurity states between conduction band (CB) and valence band (VB), but also produces more OVs as electron traps. Gram-negative Escherichia coli (E. coli) and Gram-positive Staphylococcus aureus (S. aureus) were used as evaluation systems for these materials with different Er3+ doping contents. The results showed that under the combined action of ·O 2 − and H 2 O 2 , 2.0% EBB samples with Er3+ doping content of BiOBr showed the best broad-spectrum antibacterial activity, and E. coli and S. aureus were completely inactivated at 0.03 mg ml−1 and 0.05 mg ml−1 concentrations. The surface and interfacial structures of Er/BiOBr samples were studied by XRD, brunauer-emmet-teller method, SEM, TEM and EDX. OVs and photogenerated carrier separation in Er/BiOBr were determined by ESR, PL and photochemical detection methods. More importantly, through the detection of lipid peroxidation and bacterial respiratory chain dehydrogenase activities, the internal and external processes of ROS on bacterial inactivation were determined, and the photocatalytic antibacterial mechanism was summarized. This study for the antimicrobial properties of rare earth ions doped improve photocatalytic materials provides a new train of thought. [ABSTRACT FROM AUTHOR]

Hydrogen is becoming more widely accepted as a potential energy carrier due to zero emissions, superior energy capacity, and ecological sustainability. It can be produced in a number of ways, but photocatalytic water splitting using sunlight has recently attracted attention as a sustainable option. Photocatalysts based on semiconductors, especially TiO 2 photocatalysts, have been the subject of extensive study because of their desirable physicochemical properties. There are still obstacles to overcome, however, including a wide bandgap, sluggish electron-hole recombination, and the potential for excessive H 2 generation. Numerous strategies such as doping, defect engineering, dye sensitization, and semiconductor coupling have been investigated with the goal of improving the performance of TiO 2 by discovering solutions to these limitations. This article summarizes current research on the multiple parameters affecting the photocatalytic process in dynamic H 2 generation. Surface area, particle size, TiO 2 loading, pH, temperature, light source, light intensity, sacrificial reagents, and band gap energy are all important characteristics of photocatalysts. The techno-feasible analysis, current challenges, possibility for subsequent research, and the potential for H 2 production by the photocatalytic water-splitting process are further addressed in this article. [Display omitted] • Recent attempts involving TiO 2 -based photocatalysts to produce H 2 via photocatalytic water-splitting have been addressed. • Various strategies to improve TiO 2 photocatalytic efficiency have been proposed for practical applications. • Factors affecting the TiO 2 -based photocatalytic efficiency were reviewed. • Techno feasibility analysis water-splitting have been addressed for commercialization. • Several challenges, future perspectives and strategies for development have been proposed. [ABSTRACT FROM AUTHOR]

Under ion beam radiation, surface defects in forms of nanodroplet are randomly formed on group III-V semiconductors' surfaces. This work demonstrates the effectiveness of cryo-FIB on suppressing surface nanodroplets formation. Using GaAs as a representative, it was found that the surface nanodroplets derived from a phase transition process of the arsenide atoms. The redundant gallium atoms will then accumulate and eventually form surface nanodroplets. Cryo-FIB at 80 K can effetely suppress this phase transition process, leading to a defect free surface finish. The effectiveness of cryo-FIB on other group III–V semiconductors including InP and InAs are also successfully demonstrated. [ABSTRACT FROM AUTHOR]

This article presents a theoretical investigation of phase-controlled propagation of slow light under an electromagnetically induced transparency window in a multilayered one-dimensional photonic crystal with semiconductor quantum dot nanostructures as defects. To achieve the electromagnetically induced transparency window, a setup utilizes a faint probe laser pulse alongside two powerful control laser beams arranged in a closed-loop cascade configuration. In this arrangement, a significant Kerr nonlinearity, approximately on the scale of ∼ 10 − 13 m 2 / V 2 , is discerned within the quantum dot nanostructures at a probe wavelength of 1.55 μm. It is observed that both the amplitude and the phase relationship of the control Rabi frequencies play crucial roles in governing the dynamics of the group velocity of the probe field in the quantum dot nanostructures. Under the regime of electromagnetically induced transparency, the group velocity of the probe field is significantly reduced, approximately by a factor of 10 3 times as compared to the light speed in free space. These findings hold promise for potential applications in nonlinear optics. [ABSTRACT FROM AUTHOR]

In hybrid perovskite photovoltaics (hPPV) highest reported efficiency is ∼25.2%. However, stability and toxicity are major concern towards commercialization. To improve stability, various approaches were made by research communities. Utilizing inorganic perovskite photoactive materials is one such approach to improve stability. Toxic element 'Pb' can be substituted with suitable non-toxic elements such as 'Sn' without sacrificing efficiency and stability. In CsPbI 3 , replacing Sn in place of Pb results in the PCE of ∼13%. However, efficiency of this PV is lagging 12% as compared with hybrid perovskite PV. This difference should be overcome to compete with hPPV. To improve the efficiency of inorganic PPV various experimental strategies were adopted. In this study, SCAPS simulation was carried out on FTO/TiO 2 /CsSnI 3 /spiro-OMeTAD/Au by altering E g , energetic position of conduction and valence band, defect density, and thickness of semiconductor. Obtained results were analyzed and reported in this work. [ABSTRACT FROM AUTHOR]

[Display omitted] • ZnIn 2 S 4 with strongly coupled interface was prepared by a hydrothermal method for piezoelectric photoelectrochemical reactions. • The coupled interfaces provides more active sites, which enhances the piezoelectrically polarized electric field strength. • The ultrasonic vibration enhanced ZnIn 2 S 4 nanoflowers are beneficial to carrier transport and transfer. • The photocurrent density of ZnIn 2 S 4 with strongly coupled interfaces reaches 0.46 mA/cm2 under ultrasonic conditions. In the process of photoelectrochemical (PEC) hydrodecomposition, it is important to design photoelectrode materials with low cost, high charge separation efficiency and low charge recombination rate. Herein, 2D-3D strongly coupled ZnIn 2 S 4 /β-CdS nanocomposites were prepared by a two-step hydrothermal method. Meanwhile, the piezoelectric polarization was used to induce its generation of built-in electric field, which suppressed the secondary compounding of photogenerated charge carriers caused by the interfacial structural defects of the semiconductor heterojunction. The results show that ZnIn 2 S 4 /β-CdS has better photoelectrochemical decomposition ability of water under ultrasound, and its photocurrent density increases with the increase of ultrasound frequency, reaching a maximum value of 0.46 mA·cm−2 at 1.23 V RHE , which is 3.5 times higher than that before ultrasound. In addition, by comparing the significant increase of photocurrent conversion efficiency under the applied bias voltage before and after ultrasound, it can be concluded that the enhanced catalytic activity of ZnIn 2 S 4 /β-CdS is attributed to the efficient coupling effect between ZnIn 2 S 4 and β-CdS under ultrasound conditions. This coupling effect enables the fast electron transfer at the interface between ZnIn 2 S 4 and β-CdS. Consequently, this strongly coupled nanocomposite will provide inspiration for further construction of nanocomposites for photocatalytic decomposition of water. [ABSTRACT FROM AUTHOR]

Reverse biasing triple-junction GaInP/Ga(In)As/Ge solar cells may affect their performance by the formation of permanent shunts even if the reverse breakdown voltage is not reached. In previous works, it was observed that, amid the three components, GaInP subcells are more prone to degrade when reverse biased suffering permanent damage, although they present an initial good performance. The aim of this work is, firstly, to study the characteristics of the defects that cause the catastrophic failure of the devices. For this, GaInP isotype solar cells were analysed by visual inspection and electroluminescence maps and submitted to reverse bias stress test. We find that specific growth defects (i.e. hillocks), when covered with metal, cause the degradation in the cells. SEM cross-section imaging and EDX compositional analysis of these defects reveal their complex structures, which in essence consist of material abnormally grown on and around particles present on the wafer surface before growth. The reverse bias stress test is proposed as a screening method to spot defects hidden under the metal that may not be detected by conventional screening methods. By applying a quick reverse bias stress test, we can detect those defects that cause the degradation of devices at voltages below the breakdown voltage and that may also affect their long-term reliability. • Application of reverse bias stress tests to GaInP isotype solar cells. • Degradation of devices that seem to be healthy according to their initial I-V curve. • Detection of the type of defect responsible for the degradation at reverse bias. • Physical explanation of the possible failure mechanism at the defects. • A reverse bias stress test is proposed as a screening process to spot these defects. [ABSTRACT FROM AUTHOR]

In wafer map defect pattern recognition, deep learning methods are predominantly used. These models autonomously learn features without explicit human intervention due to their black-box type network architectures. While preceding feature extraction and modality representation may seem neglected in deep learning for wafer map defect pattern recognition, we addressed this question by proposing an innovative approach. Our proposed method employs an antecedent feature learning module to create a more compact and informative hash modality representation from input wafer maps. The method exceeds in achieving high recall, crucial for identifying actual defective wafers as much as possible in semiconductor manufacturing, where defects can impact integrated circuit functionality and reliability. Smaller-sized hash modalities against larger wafer maps allow the same model to speed up the process and require fewer computational resources. [ABSTRACT FROM AUTHOR]

[Display omitted] Precisely manipulating defects in semiconductor is an effective way to improve their photocatalytic activity. In this work, bismuth oxychloride (BiOCl)/reduced graphene oxide (RGO) nanocomposites with abundant oxygen vacancies (OVs) are successfully constructed by a facile solvothermal method. BiOCl nanosheets are uniformly distributed on the RGO with superior conductivity. The RGO served as a pivotal charge transmission bridge substantially accelerates the transfer of photogenerated charge carriers, resulting in the improvement of the charge separation efficiency. The abundant oxygen vacancies in BiOCl/RGO nanocomposites increase light harvesting and enhance the adsorption of O 2 to promote the formation of superoxide free radicals (·O 2 −). By virtue of these merits, the unique BiOCl/RGO nanocomposite shows excellent degradation efficiency. When the mass ratio of RGO was 2 %, 99.07 % of 20 mg/L(100 mL) methyl orange (MO) was removed after 80 min, which was much higher than that of pure BiOCl. [ABSTRACT FROM AUTHOR]

With increasing importance of germanium (Ge) for semiconductor quantum technologies, the necessity of growing defect-free Ge films has become crucial. Here, Ge homoepitaxial growth experiments were conducted using molecular beam epitaxy (MBE). This requires a smooth ( σ r m s ≤ 10 Å) and contamination-free substrate surface. We have shown that common ex-situ wet chemical cleaning methods are not sufficient. Foreign atoms like carbon stick to the substrate surface and tend to form clusters which results in macroscopic growth defects which are referred here as pits. The density of such pits is in the range of 1 0 6 to 1 0 9 cm−2. The formation and characteristics of the pits have been investigated. Pits emerge after a growth at 370 °C with a thickness of above 5 nm. At growth temperatures lower than 300 °C, the density of pits increases, while it decreases at temperatures higher than 400 °C. Pits can be faceted with the main facets being {1 1 3} and {3 15 23}. Furthermore, a procedure is presented involving a Ge buffer growth at room temperature with a high growth rate (0.02 nm/s). This leads to a coverage of present contamination and the formation of a new substrate surface which prevent pit formation. [Display omitted] • Molecular beam epitaxy of defect-free germanium homoepitaxial layers. • Investigation of wet chemical surface cleaning methods of germanium. • Characterization of size and facets of macroscopic growth defects such as pits. • Mechanism of pit formation based on AFM, SEM, and SIMS investigations. [ABSTRACT FROM AUTHOR]

The Point Defect Model was successfully developed to study the passivation of 316LN. Steel's passive film exhibits n-type semi-conductivity with interstitial cations as the dominant point defect. The transfer coefficients α i and rate constants k i are independent of the applied potential but vary with temperature. The electronic structure of the barrier layer (bl) is discussed as a degenerate defect semiconductor in which the bl comprises essentially the depletion zone with the electronic charge and the electron-hole charge being concentrated at the metal/bl and the bl/solution interfaces, respectively. The closest classical analog is postulated to be a tunnel diode. • The Point defect model (PDM) is successfully applied to studying the passivation of 316LN in synthetic seawater. • The dominant point defect within the passive film of 316LN is the interstitial cation. • The rate constants of defect reactions for 316LN are independent of the applied potential. • The near-normal distribution of breakdown potential of 316LN is consistent with the PDM calculation. [ABSTRACT FROM AUTHOR]

Introducing defects is an effective strategy to improve the sensitivity of sulfide semiconductor sensors. In this study, ZnO obtained by calcining ZIF-8 was used as the core, and ZnIn 2 S 4 flakes were grown in situ on the outer surface of ZnO to construct a flower-cluster ZnO@ZnIn 2 S 4 composite material with an internal rich S-vacancy. The prepared ZnO@ZnIn 2 S 4 has a well-contacted ІІ-type heterojunction. Compared with ZnIn 2 S 4 , the response value of ZnO@ZnIn 2 S 4 to triethylamine gas was increased by 4.9 times, and the response recovery time was shortened from 932 s to 100 s. At a working temperature of 180°C, ZnO@ZnIn 2 S 4 exhibits a response to triethylamine that is 47.2 times higher than the response to other gases, demonstrating its specific selective response to triethylamine molecules. ZnO@ZnIn 2 S 4 can maintain a stable response to triethylamine molecules for a long time in a complex humidity environment. The selective mechanism of material selection was analyzed from the perspectives of molecular attack, molecular polarity differences, and spatial size matching. They are using calcined MOF materials as the core has excellent potential for improving the gas-sensitive response performance of materials. The explanation of the specific selectivity mechanism is positively inspiring for the construction and performance optimization of high-performance triethylamine response materials. • A flower-like structured ZnO@ZnIn 2 S 4 composite semiconductor material with a rich S vacancy was prepared. • Inducing Zn-S bond breakage creates a large number of S vacancies within ZnIn 2 S 4 structure. • At a working temperature of 180°C, ZnO@ZnIn 2 S 4 exhibited excellent selectivity towards triethylamine gas in gas tests. • Under long-term high humidity conditions, ZnO@ZnIn 2 S 4 maintained a stable response to triethylamine. • The specific selectivity mechanism of the material was explained from multiple perspectives. [ABSTRACT FROM AUTHOR]

We propose a dielectric-screening-enhancement effect for perovskite defects by using high dielectric constant organic semiconductors, thus considerably suppressing nonradiative recombination beyond defect passivation. More importantly, organic–inorganic hybrid pero-SCs with robust stabilities exhibited boosted PCEs of 23.35% (0.062 cm2) and 21.93% (1 cm2), showing less dependence. [Display omitted] Perovskite solar cells (pero-SCs) performance is essentially limited by severe non-radiative losses and ion migration. Although numerous strategies have been proposed, challenges remain in the basic understanding of their origins. Here, we report a dielectric-screening-enhancement effect for perovskite defects by using organic semiconductors with finely tuned molecular structures from the atoms level. Our method produced various perovskite films with high dielectric constant values, reduced charge capture regions, suppressed ion migration, and it provides an efficient charge transport pathway for suppressing non-radiative recombination beyond the passivation effect. The resulting pero-SCs showed a promising power conversion efficiency (PCE) of 23.35% with a high open-circuit voltage (1.22 V); and the 1-cm2 pero-SCs maintained an excellent PCE (21.93%), showing feasibility for scalable fabrication. The robust operational and thermal stabilities revealed that this method paved a new way to understand the degradation mechanism of pero-SCs, promoting the efficiency, stability and scaled fabrication of the pero-SCs. [ABSTRACT FROM AUTHOR]

The introduction of oxygen vacancies (OVs) into photocatalysts has proven to be a successful tactic to boost CO 2 reduction. However, the challenge lies in acquiring OV sites that are stable in the long term, highly dispersed, and tunable in concentration. Herein, an innovative configuration, referred to as N-Bi(3+x)+--O V, was developed for the model semiconductor Bi 2 O 2 CO 3 via an in situ anion doping approach. The structure enables the synthetic photocatalyst to exhibit superb CO 2 photoreduction performance, with approximately 100% CO selectivity and remarkable long-term stability. Experimental studies and density functional theory (DFT) calculations show that replacing O2- with N3- uniformly in the [Bi 2 O 2 ]2+ structural unit increases the chemical valence of Bi, elongates nearby Bi─O bonds, releases lattice O, improves CO 2 absorption, and decreases the energy barrier for the formation of the critical intermediate *COOH. This study offers new insights and potential opportunities for the development of reliable defect-type semiconductors and their catalytic applications. [Display omitted] • Ultrathin N-doped Bi 2 O 2 CO 3 nanosheets were constructed via a hydrothermal route. • Atomic-level dispersed N doping results in a unique N-Bi(3+x)+--O V structure. • NBOC exhibits durable CO 2 photoreduction activity and nearly 100% CO selectivity. • Mechanism of stable OVs by N doping is revealed by experimental and DFT studies. • N-Bi(3+x)+-O V stabilizes OVs, boosts CO 2 adsorption, and reduces *COOH formation energy. [ABSTRACT FROM AUTHOR]

Defects and impurities within semiconductor materials pose significant challenges. This investigation scrutinizes the response of a single dopant donor impurity located in nanostructured semiconductors, specifically quantum wells subjected to both harmonic and inharmonic confinement potentials. The primary focus of this inquiry centers on the analysis of binding energy, electron probability distribution, and diamagnetic susceptibility in connection with both the ground (1s) and excited (2p) electron states. Utilizing advanced computational techniques, specifically the Finite Elements Method (FEM) implemented through Python code, this study unveils a marked alteration in the interaction between electrons and impurities when exposed to external fields. Significantly, the characteristics of the confinement potential exert a substantial influence on the explored physical parameters. This research significantly advances our understanding of the interaction between impurities and intense fields, offering valuable insights into solid-state phenomena within low-dimensional systems. Consequently, it contributes to the design and fabrication of next-generation applications in the field of quantum well systems, encompassing areas such as lighting, detection, information processing, sensing, and energy conversion. • The study delves into the theoretical modeling of how laser and electric fields impact tunable InGaN/GaN nanostructures. • The research analyzes crucial properties, including binding energy, electron probability distribution, and diamagnetic susceptibility. • The study explores both ground and excited electron states with deeper phenomena within nanostructures. • Two types of potentials, Harmonic and Inharmonic, have been investigated. [ABSTRACT FROM AUTHOR]

• Ultra-wide bandgap semiconductors have immense potential as power switches. • The most serious materials challenge is control over electrical conductivity. • The most promising ultrawide-bandgap materials do not exhibit bipolar conductivity. Ultra-wide bandgap semiconductors, with bandgaps greater than 3.5 eV, have immense potential in power-switching electronic applications and ultraviolet light emitters. But the development of these materials faces a number of challenges, many of which relate to controlling electrical conductivity. In this work, we review the major obstacles for a set of these materials (focusing on AlGaN, AlN, BN, Ga 2 O 3 , Al 2 O 3 , and diamond) including limitations in n - and p -type doping and the effects of impurities and native point defects. We present an in-depth discussion on ultra-wide-bandgap nitride and oxide semiconductors, which face several similar challenges, as well as diamond, which presents a more unique scenario. The biggest obstacle for these semiconductors is attaining bipolar electrical conductivity, which means achieving both n -type and p -type conductivity within the same material. Toward this end, we also discuss potential future research directions that may lead to the development of bipolar ultra-wide bandgap semiconductor devices. [ABSTRACT FROM AUTHOR]

Semiconductor photocatalysis is an ideal method for wastewater treatment. However, the rapid recombination of photogenerated electron-hole pairs limits the improvement of photocatalytic efficiency. Constructing heterostructures by different energy band-matched semiconductors and surface defect engineering are considered as effective strategies to inhibit the recombination of photogenerated electron-hole pairs. Herein, a novel MgAlTi-LDH/ g -C 3 N 4 heterojunction was fabricated by in-situ growth of oxygen vacancy rich MgAlTi-LDH on ultrathin g -C 3 N 4 nanosheets first time for the degradation of methylene blue (MB) under natural sunlight. The optical absorption properties, crystalline phase, microstructure, and morphological analysis of the fabricated materials are subsequently characterized by XRD, FT-IR, UV–vis DRS, TEM, BET and XPS. Owing to Ti-doping, oxygen vacancy rich MgAlTi-LDH exhibited superior photocatalytic activity for MB degradation, which was 5.5 times of that of MgAl-LDH. Furthermore, MgAlTi-LDH/ g -C 3 N 4 heterostructures showed a higher photocatalytic activity under visible light irradiation, which was 5.9, 4.9, and 3.2 times of that of MgAl-LDH, MgAlTi-LDH and g -C 3 N 4 , respectively. Upon natural sunlight irradiation, MgAlTi-LDH/ g -C 3 N 4 can degrade 95 % of MB after 130 min of irradiation. The improvement of photocatalytic activity of MgAlTi-LDH/ g -C 3 N 4 was attributed to the synergistic effect of MgAlTi-LDH and g -C 3 N 4 , surface oxygen vacancies, and heterostructure interface. This work promotes a new strategy to synthesize high-efficiency photocatalysts for the removal of organic pollutants from wastewater by constructing heterojunctions with surface defects. [Display omitted] • 2D/2D heterojunction of MgAlTi-LDH/ g -C 3 N 4 was fabricated via a simple in-situ growth method. • MgAlTi-LDH/ g -C 3 N 4 exhibited superior activity for the photocatalytic removal of methylene blue (MB) under natural sunlight. • Ti-doping of LDH resulted in the formation of oxygen vacancies. • Synergy of oxygen vacancies and heterojunction contributed to the enhanced photocatalytic activity. [ABSTRACT FROM AUTHOR]

Semiconductor defect engineering provides an effective scheme for improving the efficiency of photocatalytic oxidation of Hg0 to Hg2+. This article mainly reviews the latest progress in photocatalyst defect engineering for photocatalytic mercury removal. The basic principles and mechanisms of photocatalysis and photon induced Hg0 oxidation are briefly summarized, including the related properties of elemental mercury, reaction pathways, and quantitative methods for mercury conversion. Subsequently, a brief summary of defect classification, synthesis strategies, and identification techniques is provided. The research progress of in situ characterization techniques for monitoring the state of defects in the Hg0 oxidation process is introduced. Particular emphasis was placed on various surface defect strategies and their key roles in improving the photocatalytic oxidation performance of Hg0, including surface vacancies (i.e., anionic and cationic vacancies), heteroatom doping i.e., metal element doping and non-metallic element doping, and atomic defined surface sites. Finally, the future opportunities, challenges, and prospects for further development of defective engineering photocatalysts for photocatalytic mercury removal are prospected. The results of this study are expected to provide profound guidance for the further design of photochemical fixed defect engineering catalysts with high activity and stability. [Display omitted] • The effects of defects on photogenerated electron-hole transfer reactions are systematically reviewed. • New methods that can effectively control photogenerated electron-hole transfer reactions are summarized. • The influence of defects on photocatalytic performance can regulate the surface catalytic performance. • This review provides a new idea for the design of efficient defect engineering mercury removal photocatalyst. [ABSTRACT FROM AUTHOR]

• Engineering strategies of vacancies in nanomaterials and types of vacancies for enhancing photothermal activity are summarized. • Fingerprints of defected-based materials are discussed and reviewed. • Challenges and perspectives for synthesis and investigation of defected-based materials for photothermal activity are discussed in the frame of nanomedecine. Upon photo-stimulation, some materials such as semiconductors can result in the generation of heat through the photothermal effect. The heat generated can be used in nanomedicine for example in cancer therapy. The response to photostimulation and the resulting photothermia can be modulated through the addition of defects in the case of semiconductors, at the heart of this review. Based on the observation that the generated nanoheat is used in photothermal catalysis and biomedical photothermia, we present here a summary of recent works in both disciplines on semiconductors that explore nanoengineering of local atomic defects, the most reported ones, to modulate the photothermal activity. We highlight the different synthesis methods and processes for creating such defects from photothermal catalysis and nanomedicine disciplines, their physicochemical and physical fingerprints elucidating their presence, and the impact of such defects on the properties and photothermal activity of such nanomaterials. In general, local defects appear to act like traps for photogenerated electrons after photo-stimulation, increasing the recombination time, and leading to non-radiative recombination and more efficient catalysis and photothermia. We also show an unpredictable optimal concertation of defects for obtaining high heating performances. Moreover, taking into account the great achievements in the field of photothermal catalysis, we translated them to the field of photothermia in nanomedicine and highlighted future perspectives in this field, at different scales for a better understanding of the relationship between the deficient structure-properties-function in heating. We believe this review, independently from the discipline, can help to elucidate aspects of photothermal activity, inspire the engineering of new defect-based materials as well as new detection methods, and bring new connections between the communities of thermal catalysis and nanomedicine. [ABSTRACT FROM AUTHOR]

The migration of intrinsic ions in metal halide perovskites and their interfaces has been shown to contribute to hysteresis and performance degradation in perovskite-based electronic devices, particularly in photovoltaics and transistors. Accordingly, controlling the film morphology, microstructure, and ionic defects in perovskite semiconductors is essential for advancing and achieving high-performance perovskite field-effect transistors (FETs). In this study, we demonstrate a well-controlled method to systematically probe the structure-property relationships, origin of hysteresis, and intrinsic ion migration effects in formamidinium iodide and lead iodide (FAI + PbI 2)-based perovskite by incorporating it in a semicrystalline conjugated poly(3-hexylthiophene) (P3HT) polymer. Optimized FETs exhibited over 100% hole mobility enhancement owing to unperturbed edge-on crystalline orientation of the P3HT chains caused by the incorporated perovskite, P3HT-(FAI + PbI 2) interactions, and better charge injection properties. However, the optimized devices exhibited improved current modulation with dual-sweep hysteresis, which was attributed to the ion migration effect contributed by the polarization of the lead/iodine-related ions and defects. Furthermore, operational stability investigation of the P3HT-(FAI + PbI 2) FETs in the air revealed gradual current decay owing to charge trapping in contrast to the control P3HT FETs. This work provides a fundamental understanding of the origin of hysteresis and instabilities in metal perovskite materials and their transistor-based devices. [Display omitted] • Charge transport were investigated in perovskite-incorporated conjugated polymer. • Optimized devices showed over 100% hole mobility enhancement. • Perovskite incorporation improved injection property. • Optimized devices exhibited hysteresis and degrading operational stability. [ABSTRACT FROM AUTHOR]

Surface defects in semiconductors play a significant role in modulating the performance of photocatalytic reactions. However, there is still insufficient exploration regarding the influence of defects on the photocatalytic CO 2 reduction performance. In this study, we achieved controllable construction of oxygen vacancies (OVs) in BiOX (X=Cl, Br) samples through one-step solvothermal treatment in polyols by adjusting the reaction time. The introduction of OVs significantly enhanced the photocatalytic activity of BiOX (X=Cl, Br) for converting CO 2 to CO. Among all the tested BiOX (X=Cl, Br) samples with OVs, BiOCl-OV-2 and BiOBr-OV-2 samples with a moderate amount of OVs exhibited the highest CO yield of 28.51 and 15.22 μmol g cat −1 after 4 hours of irradiation, respectively. Photo-/electrochemical measurements results revealed that engineering OVs into BiOX (X=Cl, Br) effectively adjusted their electronic structure, charge density and separation; however, excessive OVs may slightly degrade their photoelectrochemical properties and thus lead to reduced photocatalytic activity. Furthermore, an appropriate amount of OV was found to enhance both CO 2 adsorption capacity and photo-generated electron reduction ability, thereby further promoting the overall efficiency of photocatalytic CO 2 conversion. Through in situ FTIR spectra analysis, we uncovered the process of photocatalytic conversion from CO 2 to CO. [Display omitted] • Controllable construction of oxygen vacancy (OV) was achieved in BiOX (X=Cl, Br) • The introduction of OVs significantly enhanced photocatalytic activity of BiOX • Engineering OVs into BiOX effectively mediated the photoelectrochemical properties • Appropriate amount of OV promoted both CO 2 adsorption and electron reduction • The photocatalytic conversion form CO 2 to CO was elucidated by in-situ FT-IR spectra [ABSTRACT FROM AUTHOR]

Defect engineering and heterojunction are the two dominant methods to improve the efficiency of semiconductor photocatalysis. Loading can also improve the performance of photocatalysts and solve the problems of photocatalyst agglomeration and difficult recovery in water. In this paper, a ternary ZnIn 2 S 4 /TiO 2 /MS-SiO 2 composite photocatalyst (EG-ZIS/TS) was constructed by sequentially loading nano-TiO 2 and defective state ZnIn 2 S 4 (EG-ZIS) on industrial by-product SiO 2 microspheres (MS-SiO 2). Among them, EG-ZIS was prepared with ethylene glycol as a solvent. Compared with EG-ZIS/T (unloaded MS-SiO 2) and ZIS/TS (non-defected state ZnIn 2 S 4), the degradation performance of methyl orange (MO) solution and the reduction performance of hexavalent chromium under simulated daylight irradiation were substantially improved. As a result, Zn defects enhanced the photocatalytic performance of ZnIn 2 S 4 and the heterojunction between ZnIn 2 S 4 and TiO 2 , and this enhancement was achieved by adjusting the work function of the system and promoting interface electronic transmission. The loading of MS-SiO 2 further produced a synergistic effect of enhancing the heterojunction photocatalytic efficiency by improving the dispersion and immobilization of TiO 2 and EG-ZIS. The effect of ethylene glycol on the curvature and surface Zn defectivity of ZnIn 2 S 4 nanosheets was also investigated in this study. This study provides an innovative approach to improve the oxidation and reduction performance of photocatalysts by combining semiconductor defect, heterojunction, and loading on the carrier surface and finds that the loading of photocatalysts on the SiO 2 carrier surface has an enhancement effect on the performance of the formed heterojunction. This thesis is useful and informative for related research. [Display omitted] • ZnIn 2 S 4 with surface Zn defects was prepared using ethylene glycol as solvent. • Construct a heterojunction between the defect ZnIn 2 S 4 and nano TiO 2. • Load EG-ZnIn 2 S 4 /TiO 2 onto industrial byproduct SiO 2 microspheres. • Defect, heterostructure, and carrier jointly enhance the performance of photocatalysts. • This paper provides a solution for industrial treatment of pollutants in water. [ABSTRACT FROM AUTHOR]

The electrical properties of ternary PVDF/PANI/MWCNT nanocomposite with 0–15 wt% content of multi-walled carbon nanotubes (MWCNT) were investigated. It was found that, in the studied temperature range of 4.2–340 K, two semiconductor impurity conduction mechanisms appear in their pure form. The charge carrier transfer at low temperatures occurs through localized states due to the Efros-Shklovskii variable range hopping mechanism. At near room temperatures (~200–300 K), the temperature dependence of conductivity shows Arrhenius behavior with activation energy of 10–30 meV. The observed energy corresponds to the excitation of charge carriers from impurity states to the mobility edge. It was found that the MWCNT content affects electrical parameters such as localization length, density of localized states at the Fermi level, dielectric constant, Coulomb gap width, and activation energy of charge carriers to the mobility edge. The increase in the carbon nanotube content leads to a qualitative change in the conductive network properties from PANI-like to MWCNT-like. It was shown that there is a significant transition range in the temperature dependence of conductivity between temperature intervals where hopping conductivity and Arrhenius behavior appear in their pure form. [Display omitted] • Qualitative changes in conduction network from PANI-like to MWCNT-like properties • Efros-Shklovskii variable range hopping conductivity at helium temperatures • Arrhenius behavior of electrical conductivity at near room temperatures • Transition range between conduction mechanisms [ABSTRACT FROM AUTHOR]

The substitutional doping of graphene and related materials with Boron (B) and/or Nitrogen (N) atoms can be effectively used to tailor their properties for specific applications. In this paper, we investigate the energetics, electronic structures and vibrational spectra of substitutional pair-defects in graphene and graphane. The structural distortions in the vicinity of BN pair-defects are small as compared to the distortions in the vicinity of BB or NN pair-defects. The BB (NN) pair-defects in graphene and graphane transform them into p (n) semiconductors. However, the BN pair-defects doped graphene and graphane are intrinsic semiconductors. The Raman and IR spectra of above mentioned pair-defects have unique features, which can be used to identify these defects in graphene as well as graphane structures. [Display omitted] • Substitutional pair-defects doped in graphene and graphane show their signatures in electronic and optical properties. • BB (NN) pair-defects in graphene and graphane transform them into p(n) type semiconductors. • Raman and IR spectra of pair-defects have unique features, which can be used to identify these defects in graphene as well as graphane structures. [ABSTRACT FROM AUTHOR]

BiOCl materials have received much attention because of their unique optical and electrical properties. Still, their unsatisfactory catalytic performance has been troubling researchers, limiting the application of BiOCl-based photocatalysts. Therefore, many researchers have studied the adjustment of BiOCl-based materials to enhance photocatalytic efficiency. This review focuses on surface and interface engineering strategies for boosting the photocatalytic performance of BiOCl-based nanomaterials, including forming oxygen vacancy defects, constructing metal/BiOCl, and the fabrication of semiconductor/BiOCl nanocomposites. The photocatalytic applications of the above composites are also concluded in photodegradation of aqueous pollutants, photocatalytic NO removal, photo-induced H 2 production, and CO 2 reduction. Special emphasis has been given to the modification methods of BiOCl and photocatalytic mechanisms to provide a more detailed understanding for researchers in the fields of energy conversion and materials sciences. [Display omitted] • Advances in the surface and interface engineering of BiOCl nanomaterials are described. • Formation of vacancies, metal/BiOCl junctions, and heterojunctions are described. • Applications in photocatalysis are demonstrated in detail. [ABSTRACT FROM AUTHOR]

• Comprehensive admittance spectroscopy investigation of three defects in Ga 2 O 3. • Extraction of temperature-dependent activation energy and capture cross-section. • Extraction of electron mobility from bias-dependent admittance spectroscopy. We present a comprehensive investigation of electrically active defects and transport properties in commercial (̅201) edge edge-defined film-fed growth β-Ga 2 O 3 using admittance spectroscopy measurements from 14 K up to 450 K. Isothermal capacitance-frequency measurements were conducted from 410 to 450 K to resolve a defect ∼0.8 eV below the conduction band edge and compared with deep-level transient spectroscopy and isothermal capacitance transient spectroscopy measurements. We report significant non-Arrhenius behavior of a defect ∼100 meV below the conduction band and apply the Arrhenius transformation matching method to extract its temperature-dependent activation energy and capture cross-section in the temperature range of 75 to 195 K. At low temperatures (<50 K), we use bias-dependent admittance spectroscopy to extract the electron mobility in β-Ga 2 O 3 from the modified dielectric relaxation frequency. Finally, we discuss the potential of admittance spectroscopy for defect characterization in wide bandgap semiconductors in terms of the defect detection range, instrument requirements, and the frequency-temperature experiment space. [ABSTRACT FROM AUTHOR]

Xylene is a highly carcinogenic inert gas, and achieving highly selective detection toward xylene gas is crucial for environmental protection and physical health. Herein, α-Fe 2 O 3 nanoparticles doped with different Zn contents (ZF-0, ZF-1, ZF-2 and ZF-3) have been prepared through a feasible solvothermal and subsequent annealing treatment. The successful doping of Zn has been confirmed through EDS, XPS and XRD characterizations. After Zn doping, the baseline resistance in air reduces, the band gap and specific surface area decrease, but oxygen vacancy defects increase for α-Fe 2 O 3 nanoparticles. When applied as gas sensors, all as-prepared α-Fe 2 O 3 samples show typical p-type semiconductor gas sensing behaviors. Especially, the ZF-2 sample with appropriate amount of Zn doping exhibits an excellent xylene gas sensing selectivity. Meanwhile, the ZF-2 sensor shows a high response, fast response/recovery speed, well stability and repeatability and a detection limit of 5 ppm at 240 °C. The acceptor level and oxygen vacancy defects in ZF-2 nanoparticles promote the catalytic oxidation of xylene gas by p-type Zn-doped α-Fe 2 O 3 oxide semiconductors, thereby resulting in better xylene gas sensing performance. [Display omitted] • A series of Zn-doped α-Fe 2 O 3 nanoparticles have been prepared. • Zn-doped α-Fe 2 O 3 nanoparticles show p-type semiconductor sensing behaviors. • Highly selective and rapid xylene detection of Zn-doped α-Fe 2 O 3 nanoparticles. • The electronic structure regulation improves xylene gas sensing properties. [ABSTRACT FROM AUTHOR]

This paper presents a study of the effect of 1 MeV electron irradiation on the localization of charge carriers in graphene quantum dots (GQDs) located in a reduced graphene oxide (RGO). The electrical properties were analyzed in a wide temperature range of 4.2–340 K for fluences of 0–160 × 1015 cm−2. The localization length, dielectric permittivity, and density of localized states were estimated. It was found that the conductivity and charge localization parameters exhibit non-monotonic behavior depending on the electron fluences. It can change several times in the vicinity of a fluence of 10 × 1015 cm−2 compared to the higher or lower fluence. It is shown that electron irradiation affects the disordered surrounding matrix, which leads to an increase in the content of oxygen and functional groups. At the same time, the size of the sp 2 ‑carbon domains does not depend on the fluence. It is assumed that electron irradiation indirectly affects the properties of GQDs. The transformation of the surrounding disordered matrix leads to a modification of the electronic properties of the GQDs array and the RGO as a whole. The non-monotonic behavior of the RGO conductivity upon irradiation is due to the features of the energy spectrum of the GQDs array, which is characterized by the presence of periodic peaks in the density of states. The irradiation-induced structural modification likely leads to a shift in the Fermi level and a change in the density of states. It is shown that the RGO behaves like a wide-band doped semiconductor. The difference is that the impurity level was formed by GQDs. At temperatures above 310 K, the RGO conductivity exhibits an Arrhenius behavior with an activation energy of about 60 meV due to charge carrier delocalization at thermal ejection into the extended band. [Display omitted] • Quantum-dot-like charge transfer in reduced graphene oxide • Non-monotonic behavior of conductivity and localization parameters under irradiation • Localization length can be greater or less than the sp2 ‑carbon region size. • Impurity conductivity in a wide temperature range • Sequential change of semiconductor mechanisms of impurity conduction [ABSTRACT FROM AUTHOR]

Herein, we have developed a visible light-responsive black TiO 2 photocatalytic coating with controlled formation of oxygen vacancies (OV) and Ti3+ species, crucial for enhancing photocatalytic reactions. The rational control of these semiconductor defects was achieved through plasma electrolytic oxidation (PEO), followed by NaOH post-treatment. The coating's effectiveness was evaluated by tetracycline (TC) degradation. The surface defects function as traps, reducing electron/hole recombination and forming mid-gap/localized-donor states, narrowing the band gap. Rigorous material characterization confirmed unaffected morphology and PEO coating phases, while increasing the density of OVs and Ti3+ species. As a result, TC photo-degradation was ∼3.5 times higher compared to plain PEO coatings. The material demonstrated exceptional stability and efficiency, while it was successfully intensified via peroxymonosulfate (PMS) activation, leading to high synergies (2.10). Scavenger tests revealed the existence of both radical/non-radical pathways, indicating the prevailing photocatalytic mechanism and the key differences achieved through this novel process. [Display omitted] • PEO coatings with different amounts of oxygen vacancies were successfully produced. • Optimal amount of surface defects exhibited an enhanced photocatalytic tetracycline degradation. • Optimal oxygen-vacancy rich PEO coatings showed excellent ability in PMS activation. • Various approaches for oxygen vacancy formation were compared." • The pathway and mechanism of TC photodegradation have been fully elucidated. [ABSTRACT FROM AUTHOR]

• Charge trapping effects are considered as one of the most severe reliability issues in GaN/AlGaNMIS-HEMTs. • Thus, the identification of the origin and the physical properties of active defects is one of the key factors to improve the stability of GaN technology. • In this work, we suggest two neighboring nitrogen vacancies as the origin of correlated random telegraph noise (RTN) emissions in a GaN/AlGaN fin-MIS-HEMT. • Electrostatic coupling between these two defects is calculated using three different approaches and the results are verified using a Hidden Markov Model (HMM). Charge trapping effects are considered as one of the most severe reliability issues in gallium nitride (GaN)/aluminium gallium nitride (AlGaN) metal-insulator-semiconductor HEMTs (MISHEMTs). Thus, the identification of the origin and the physical properties of active defects is one of the key factors to improve the stability of GaN technology. In this work, we suggest two neighboring nitrogen vacancies as the origin of correlated random telegraph noise (RTN) emissions in a GaN/AlGaN fin-MISHEMT. We determine the magnitude of electrostatic coupling between these two defects by using three different approaches and verify the results by simulating the RTN emissions of a similar system using a Hidden Markov Model (HMM). [ABSTRACT FROM AUTHOR]

To develop a high voltage read margin Δ V rd , deep reset engineering and defect engineering are proposed. To realize the defect engineering, the amount of oxygen vacancy of the resistor was controlled by optimizing the material of the reservoir (RSV) and switching oxide. We investigated the barrier height modulation, which was formed by the Ru bottom electrode (BE) having a high work function, to demonstrate the concept of deep reset engineering by reducing the set current (I set) of the HfO 2 resistor (1R) to the turn-on current (I th) of the selector device (1S). Further, we identified the causes of the negative set fail through the chemical analysis of the HfO 2 /BE TiN interface to improve the reset switching fail. Unstable TiON and TiOx chemical species, which present in the interface of HfO 2 /BE TiN, take oxygen from the resistor HfO 2 and create the parasitic defect (or filament), which was injected from BE TiN. To improve the negative set fail of RRAM, we proposed the O 3 surface treatment of BE TiN at a high temperature (∼320 °C) and the BE Ru with a superior oxidation resistance. By using deep reset engineering, we successfully increased the Δ V rd of 1S1R by more than 0.5 V. We also demonstrated that Ru BE and the O 3 surface treatment of BE TiN improved both the reset window and the negative set. [ABSTRACT FROM AUTHOR]

Defects in layered semiconductors cause large variation of electric and catalysis properties, and exploiting defect-involved reaction can deeply excavate unearthed characteristics with significant performances. Mo-terminated defects of MoS 2 spontaneously guide the oriented growths of ultrasmall Au nanocrystals on specific sites of liquid-exfoliated (LE) nanosheets, which are experimentally and theoretically performed with programmable heterostructures. The conjugated construction of Au plasmonics and MoS 2 semiconductors is manipulated with the aim of the optimal synergistic activity. Additionally, with photonic irradiation, hot electrons excited from attached plasmonic nanostructures are injected into MoS 2 semiconductors, which remarkably increases the carrier density of catalyst to match the energy level of hydrogen evolution reaction (HER). Obeying the principle of proximity, localized MoS 2 defect-adjacent Au plasmonics exhibit a more valid pathway, transferring hot electrons from donators to receptors of catalytic sites, in comparison to planar Au decoration. Meanwhile, Au nanostructures located at basal planes are essential for accelerated electron transport rates between catalysts and electrodes, and high stabilities in plasmonic-motivated electrocatalytic performances are guaranteed. The dual function of location-discriminated Au nanostructures accounts for superior electrocatalytic HER performances with photonic excitation, which imparts high inspiration in expanded heterostructures and integrated plasmonic techniques for catalysis and devices. Image 1 • MoS 2 defects guide the oriented growths of Au nanocrystals on 2D nanosheets. • Au/MoS 2 heterostructrues are experimentally and theoretically manipulated. • Plasmonic hot electrons motivate catalyst defects with enhanced electrocatalysis. • Dual function of Au nanostructures on semiconductor electrocatalysis is exploited. [ABSTRACT FROM AUTHOR]

Abstract Previous electron spin resonance investigations correlated with data from cathodoluminscence and photoluminescence measurements have shown that impurity ions consisting mainly of isotopes with zero nuclear moments are involved in the structure of the observed paramagnetic point defects. In the present microstructural and compositional investigation we demonstrate that oxygen, carbon and silicon impurity atoms exhibiting low natural content of isotopes with non-zero nuclear spin are indeed present in cBN crystallites selected from amber coloured BORAZON CBN400 and CBN 500 super abrasive powders, as well as in the black coloured BORAZON CBN1000 and CBN Type 1. It is also shown that aggregates of impurity atoms are present next to the extended cBN lattice defects, which could explain the non-uniform distribution of the electro- and opto-active impurities reported in a spectroscopy investigation. Highlights • cBN crystals contain extended defects such as dislocations, stacking faults and twins. • The nature and distribution of impurities in cBN crystals is revealed by EDS and EELS. • Oxygen, silicon and carbon impurities are not uniformly distributed in cBN crystals. • The detected impurities can agglomerate at extended defects or form precipitates. [ABSTRACT FROM AUTHOR]

Highlights • First comprehensive microkinetic model developed for defects in oxide semiconductor. • Model accounts for Ti and O interstitial behavior near a TiO 2 (1 1 0) surface. • Model accounts for roles of extended defects and a surface with a foreign adsorbate. • These roles combine to strongly affect mean diffusion length of oxygen interstitials. Abstract The kinetics and diffusion mechanism of surface-injected oxygen interstitials (O i) in TiO 2 (1 1 0) were investigated using a microkinetics model in order to determine the effects of different conditions upon to the O i reaction-diffusion network. Extended defects, whether incipient or pre-existing, may act as a source or sink for O i. The present work uses a quantitative microkinetic model to describe this diffusion and reaction network based upon isotopic gas-solid exchange experiments. Pertinent outputs from the model determined that the activation barrier for surface injection of O i is 2.4 eV, while dissolution of O i from extended defect is 3.3 eV. The interstitial sequestration mechanism through extended defects leads to kinetic coupling effects that other sequestration mechanisms would not typically induce. [ABSTRACT FROM AUTHOR]

In the field of spintronics, it is incredibly challenging to modulate or change the charge carrier transport behavior of field effect transistors (FET) under ambient conditions with magnetic field which is driven by transfer of spin polarization across the junctions. Here, we fabricated electrolyte gated - field effect transistor (EG-FET), which consists of polyaniline (PANI) as defect rich semiconductor and granular nickel as planar electrode with 1-hexyl 3-methylimidazolium chloride electrolyte. The polyaniline used was synthesized by oxidative polymerization and characterized with FTIR spectroscopy and current - voltage (I–V) characteristics with days establishing a defect rich semiconductor stable in an ionic environment. The individual junction characteristic showed presence of interface polarization and tunability of barrier height (ϕ b) and ideality factor (η) with a magnetic field. Here, a strong unsaturated negative junction magnetoresistance (MR) of the order of 44% indicated presence of spin polarized electrons at the junction mediating an interface magnetocapacitance. Further, the output characteristics of the device showed a tunable positive MR of the order of 5000% with appropriate drain and gate voltage. The threshold voltage (V T) and mobility (μ) of EG-FET were also found to be a function of the magnetic field. This study provides valuable insights into the use of magnetic electrodes in EG-FETs and forms a novel architecture for ion based spintronics. [ABSTRACT FROM AUTHOR]

The synergistic regulation effects on the structure and electronic properties of graphene by methane plasma, Stone-Wales defect and equibiaxial strain has been investigated. It is found that the graphene containing Stone-Wales defect (SWG77) has metallicity, when surface adsorbing a CH 3 +ion, CH 3 +@SWG77 is a semiconductor with 0.339 eV indirect band gap. The stress-strain curve results indicate that adsorbing different plasma fragments in methane may influence to varying degrees on the ultimate strain of the SWG77 system. The hole mobility has an enhanced tendency as the tensile strain increases for the CH 3 +@SWG77 system. In addition, the hole mobilities seem to reach saturation when applied equibiaxial strain increase to 2 % or larger. Applying equibiaxial strain on the system substrate, the band gaps of CH 3 +@ SWG77 and 2CH 3 +@ SWG77 systems are almost unaffected. In addition, the concentration of CH 3 + ion has a certain effect on the light absorption coefficient, reflectivity, and energy loss of the SWG77 system in the visible light region (1.62 eV–3.11 eV) and ultraviolet regions (3.11 eV–5.50 eV). Therefore, defect graphene with appropriate carrier mobility and band gap may be designed by adjusting the equiaxial strain and methyl concentration, which provides useful theoretical support for the development of optical electrical multifunctional electronic devices based on graphene, and is conducive to promoting the application of graphene materials in the field of band gap engineering. [Display omitted] • The types of plasma fragments in the methane can affect the ultimate strain of the SWG77 system in varying extents. • The hole mobility has an enhanced tendency as the tensile strain increases for the CH 3 +@SWG77 system. • The concentration of CH 3 + ion has a certain effect on the electronic structure and optic properties of SWG77. • Defect graphene may be designed by adjusting the equiaxial strain and methyl concentration. [ABSTRACT FROM AUTHOR]

Wafer map defect pattern recognition is an indispensable part in the semiconductor manufacturing process. Wafer map defect pattern recognition and classification can locate the cause of failures in the manufacturing process. In this study, we propose a deep convolutional neural network architecture incorporating improved convolutional block attention module (I-CBAM) for pattern recognition and classification of single-type wafer map defects. The proposed method consists of three steps: First, a multi-branch attention module is designed, which focuses more on the main information of defect clusters, extracts richer feature information, and improves feature extraction capabilities. Secondly, I-CBAM is integrated into the ResneXt50 backbone network to extract wafer map defect features. Finally, the extracted features are fed to a support vector machine combined with an error-correcting output code to classify the wafer map defect pattern. The experimental results on the real-world datasets WM-811K show that the accuracy rate of the I-CBAM-ResneXt50 can reach 96.96%. Compared with the existing algorithms, the proposed model can achieve better recognition and classification results. [ABSTRACT FROM AUTHOR]

In the semiconductor manufacturing process, analyzing the defect patterns on a wafer map is crucial for identifying the causes of the defects. The advent of convolutional neural networks (CNNs) has significantly increased the accuracy of automated wafer map pattern classification. Generally, the use of a larger training dataset results in higher classification accuracy. However, collecting a large number of wafer maps and labeling them with their defect categories is expensive and time-consuming. In this paper, we present an improved training method under data insufficiency for wafer map pattern classification. We apply supervised contrastive learning to train a CNN by exploiting the rotational-invariant characteristic of wafer map labeling. The CNN is trained by simultaneously minimizing two loss functions: classification loss and contrastive loss. The first loss function is to classify the rotational variants of wafer maps accurately. The second loss function is to align the representation vectors for the rotational variants of wafer maps with similar labels to be close to each other. Using two benchmark datasets, WM-811K and MixedWM38, we demonstrate that the proposed method enhances classification accuracy compared with existing methods, particularly when the training dataset is small. [ABSTRACT FROM AUTHOR]

Automated optical inspection (AOI) technology has been widely used for defect detection in various industries including wafer maps and TFT-LCD. Although the implementation of AOI significantly reduce the efforts of manual visual tests, most of the automated were leaving out defect classification for manual inspection. Previous studies indicate that various technologies including statistical methods or machine learning techniques can be used to classify the defect images. Among them, convolutional neural networks (CNN) bring out attention to classification problems. Indeed, determining the suitable choices of the critical hyperparameters is crucial for classification performances. However, most related studies determine the hyperparameters by testing the performance among a few combinations. Despite some previous studies integrating metaheuristics with CNN to improve the selection of hyperparameters, only a few studies focus on AOI defect classification by using CNN with hyperparameter optimization. This study proposed an opposite-based particle swarm optimization with CNN (OPSO-CNN) to deal with the AOI defect classification of semiconductor photomask while considering the hyperparameter optimization of the proposed CNN model, in which opposite-based initialization mechanism was used to generate the initial particles to increase the diversity of the searching space. An empirical study was conducted to evaluate the performances of the proposed OPSO-CNN by the benchmarks. The results have shown the practical viability of the proposed model. • An OPSO-CNN model is proposed to deal with the AOI defect classification of semiconductor photomasks. • Metaheuristic is integrated to improve the selection of the hyperparameters of CNN. • An opposite-based initialization is implemented to increase the diversity of the searching space of PSO. • EfficientNet, DenseNet, and ResNet have experimented to the proposed problem. • An empirical study is conducted in a semiconductor company and has shown practical viability. [ABSTRACT FROM AUTHOR]

• Nanocomposite exhibits properties similar to doped semiconductors. • Efros-Shklovskii variable range hopping conductivity at helium temperatures. • Arrhenius behavior of electrical conductivity at near room temperatures. • Wide transition region of 20–230 K where conduction mechanisms act simultaneously. The electric charge transfer in a ternary nanocomposite based on polyaniline and multi-walled carbon nanotubes distributed in the dielectric matrix of polyvinylidene fluoride was studied in the wide temperature range of 4.2–340 K. The studied material exhibits properties similar to doped semiconductors. A sequence change in the semiconductor mechanisms of impurity conduction with increasing temperature is observed. The variable range hopping conduction dominates at helium temperatures. The excitation of charge carriers from the impurity level to the extended states provides conductivity at near room temperature. The existence of a wide transition region in the range 20–230 K, where both conduction mechanisms act simultaneously, was shown. [ABSTRACT FROM AUTHOR]

• The medium-P Ni films were formed on Al, Cu, Ni and Fe substrates by electroplating. • The thermal expansions of the Ni-P film and the substrates to 600 °C were measured. • Even heating at 400 °C caused no cracks in the Ni-P films on Ni and Fe substrates. • Cracks in the Ni-P film occurred from the interface with the Al and Cu substrates. Automotive power semiconductors are required not to fail at high-temperature mounting (∼400 °C), and a structural design that prevents defects as well as cracks is essential. In this study, we focused on the thermal expansion coefficient of medium-phosphorus Ni films (P content: 8–9 wt%), which are commonly used for soldering or wire-bonding, with the substrates on which they are electroplated to investigate the effects of high-temperature heating on cracks induced in the Ni films. The Ni-P films were deposited on Al, Cu, Ni, and Fe substrates via electroplating technique using a Watts bath containing phosphorous acid. By heating to approximately 360 °C, the Ni-P film shrank because of the phase transition to a phosphorus compound mainly composed of Ni 3 P. As a result of the Ni film indentation test after heating to 400 °C, cracks were induced in the Ni film on the Cu substrate but not on the Ni substrate. The thermal expansion coefficients of the Cu and Ni substrates at approximately 360 °C were 17.4 and 14.8 µm m−1 °C−1, respectively; suggesting that the residual stress at the interface between the Ni film and the substrate affects cracking. [ABSTRACT FROM AUTHOR]

The clear correlation of defect localization by Electroluminescence to nanometer sized defects at Schottky gate contacts of GaN HEMTs are always challenging and limiting the root cause analysis of the stress related electrical degradation of the devices. In this paper a novel approach combining large area planar TEM defect screening followed by cross sectional preparation at identified defect sites is demonstrated to get access to relevant structural damages at the gate. The analysis flow is applied for normally-on GaN HEMT devices with an increased leakage at the Schottky gates observed after electrical stressing. To initiate electrical active degradation these devices were stressed up to significant changes in the electrical performance and then Electroluminescence spots were detected identifying possible defect positions. Metal intrusions into the AlGaN/ GaN stack underneath the Schottky gate contacts of only 20 nm size could be found by the newly combined planar/ cross-sectional analysis flow in good correlation to the EL spot positions. Analytical TEM investigations of the defects reveal Pt and Au inside the semiconductor reaching the 2DEG at a threading dislocation of the HEMT. These intrusions contribute to the gate leakage current and are causing the increased leakage current after electrical testing. • Gate leakage in GaN HEMTs by current driven metal intrusions at Schottky gate • Improved correlation of electroluminescence signal with structural defects • Failure mode in GaN HEMT analyzed by analytical TEM [ABSTRACT FROM AUTHOR]

Extremely efficient phosphorus drive-in into a high resistivity (100) Si substrate is achieved by an advanced doping technology, providing precise control over the amount of electrically active impurity dopants that are introduced into the semiconductor. A phosphorus δ-layer on deglazed and not deglazed silicon surfaces is formed by means of polystyrene homopolymers terminated with a P containing moiety. The P atoms from the δ-layer are injected into the Si substrate by a standard high temperature annealing in a rapid thermal processing (RTP) machine, operating at 1200 °C for 5 s. Depth distribution of the P atoms upon the drive-in procedure is investigated by ToF-SIMS analysis, highlighting the effective capability to inject the dopant impurities into the semiconductor substrate. Room temperature Hall measurements in van der Pauw configuration are performed as a function of the processing conditions to investigate the activation rates (η a) of injected P atoms. Remarkably, depending on the surface characteristic before the grafting of the phosphorus terminated polymers, significantly different η a values are attained. More precisely η a ∼80% are achieved in the case of not deglazed Si surfaces. Conversely η a ∼100% are measured in the case of deglazed Si surfaces, providing a clear evidence of a full activation of the dopant impurities injected into the silicon substrate. These experimental results path the way to the development of a mild and efficient technology for the doping of semiconductors. [ABSTRACT FROM AUTHOR]

In this work, high quality AlPN films are grown with an improved MOCVD system, in which the source transport circuit is adjusted to suppress the pre-reaction of Al and P. The mechanism of P incorporation into AlN, including the formation and characteristics of P anti-site defects in AlPN are investigated. In addition, the relationship between the P anti-site defects and the crystal quality is analyzed in detail. Further, high quality AlPN/GaN heterostructure with high density of sheet carriers and low leakage is grown, which are attributed to the lower N vacancies and lower surface status of AlPN barrier. The results in this work not only demonstrate the great potential of AlPN based structures in electronic device applications, but also provide instructive principles, such as anti-site defects, restraining pre-reactions, strain states, electrical properties and surface states in studying the novel N-rich group III-V semiconductors. • High quality AlPN films are grown by the modified MOCVD. • The mechanism of P incorporation into AlN is analyzed in detail. • AlPN/GaN heterostructure with high density of sheet carriers and low barrier leakage is grown. [ABSTRACT FROM AUTHOR]

[Display omitted] • Synthesis of CuO-doped YVO 4 by the simple sol–gel approach. • CuO incorporating can effectively enhance the physicochemical, optical, and photocatalytic properties. • Complete Atrazine photodegradation achieved in 50 min by CuO-YVO 4. • The degradation rate of 15 wt% CuO-YVO 4 was 46.3 times higher than pristine YVO 4. • CuO-YVO 4 can be recycled five runs without loss in its activity. Herbicide photocatalytic oxidation across nanostructured semiconductor-based photocatalysts demonstrated an appropriate strategy for controlling the resulting environmental problems. Developing a recyclable and efficacious photocatalyst is a challenge to overcome the semiconductor defects like instability and quick recombination. A series of CuO-YVO 4 nanocomposites with different concentrations of CuO were synthesized by the surfactant sol–gel method. The different characterization techniques approved the structures and morphology of the as-prepared nanocomposites. The Atrazine degradation in water under illumination with visible light was used to assess the photocatalytic performance of the as-synthesized CuO-YVO 4 nanocomposites. It demonstrates that combining CuO nanoparticles (NPs) can significantly enhance the photocatalytic activity of YVO 4. The full photooxidation of Atrazine was achieved over 1.6 g/L of 15 wt% CuO-YVO 4 with an outstanding rate constant of 0.0518 min−1 about 51.8 times greater than that in pristine YVO 4 (0.001 min−1) and keeping recyclability of 96.5%. The maximal photodegradation efficiency of 15 wt% CuO-YVO 4 is likely relevant to suppressing charge recombination with enhanced light harvesting. The Atrazine photocatalytic degradation mechanism was suggested. The results of this research will pave the way for the widespread application of oxide-vanadate semiconductor photocatalysts for the photocatalytic oxidation of herbicide contaminates in water under visible illumination. [ABSTRACT FROM AUTHOR]

Abstract Photoreflectance spectroscopy is used to study optical properties of GaNPAs for the intermediate band (IB) solar cell absorbers. The IB is created in GaNPAs by the incorporation of ~2% of N atoms and the required partial occupation of the intermediate band with electrons is realized by doping with Si donors. Undoped and p -type doped (Be doped) GaNPAs films are studied as a references. Observation of all three absorption bands: VB → IB (a transition between the valence band and the IB), VB → CB (a transition between the valence band and the conduction band), and IB → CB (a transition between the IB and the conduction band), demonstrate that n -type doped GaNPAs layers act as intermediate band solar cell absorbers. Highlights • Photoreflectance has been applied to study optical transitions in Si-doped GaNPAs:Si layers with the Intermediate Band partially occupied by electrons. • Optical transitions related to three absorption bands, have been identified in the PR spectra. • It has been shown that broadening and intensities of optical transitions strongly depend on the doping concentration. [ABSTRACT FROM AUTHOR]

Abstract Thermoluminescence of a high temperature secondary glow-peak in natural quartz annealed at 900 °C is reported. The glow-curve of a sample irradiated to 10 Gy and measured at 1 °C/s shows three peaks; the main peak at 71 °C and two other weaker-intensity peaks at 125 °C and 177 °C. For reference, the peaks are labelled as I, II and III. This study is concerned with the secondary peak at 177 °C (peak III). The electron trap responsible for peak III is stable at ambient temperature as determined by monitoring the peak intensity after various delays between irradiation and measurement. The activation energy and frequency factor of the peak were estimated as ~1.24 eV and ~1012 s−1 respectively. The dose response of the peak in the range 1–300 Gy is sublinear. The influence of either partial heating or irradiation dose on the peak position suggest that the peak follows non-first-order kinetics. [ABSTRACT FROM AUTHOR]

Abstract Understanding the energy response of dosimeters and scintillators for measurements of ionising radiation is an important area in the field of solid state dosimetry. Such an understanding is particularly critical for source calibration and for quantifying effective dose (rates) in wide-energy mixed-radiation fields. While there have been several investigations on characterising the ionising- energy response of artificial dosimeters (e.g. LiF, Al 2 O 3 :C, etc.), there exist no studies on natural dosimeters such as quartz and feldspar which are extensively used in luminescence geochronology and retrospective dosimetry. Currently, luminescence geochronology assumes that all beta and gamma irradiations in nature (from the decay of K, the U and Th radioactive chains) are equivalent in terms of luminescence production per unit dose to each other, and to the laboratory 137Cs, 60Co (gamma) and 90Sr/90Y (beta) irradiations used for calibration and/or equivalent dose determination. In this study, we experimentally determine the quartz Optically Stimulated Luminescence (OSL) and feldspar Infra-Red Stimulated Luminescence (IRSL: IRSL at 50 °C and post-IR IRSL at 290 °C) response to irradiations with photons of in the energy range 8–250 keV. We show that microdosimetric effects lead to a steady, significant decrease in quartz OSL production efficiency for < 80 keV photons. Similar to quartz, the local saturation of the electron traps also leads to a systematic decrease in luminescence efficiency for < 120 keV photons in feldspar; however, this effect competes with an increase in recombination efficiency due an increased number density of hole centres in the vicinity of the trap, thus giving a peak-shaped IRSL efficiency response in the range of 250–8 keV. Our results suggest that dose-rate conversion factors, specific to radiation type and radioisotope, should be used for age calculation, and significant care should be taken for luminescence based calibration of the dose rate of the laboratory irradiation source. [ABSTRACT FROM AUTHOR]

Abstract Development of novel electronic devices is an area of active research which reveals the potential of organic nano-materials towards efficient nano-devices application. In this letter, we have investigated the electronic transport properties of nitrogen (N) doped disconnected zigzag graphene nanoribbons (ZGNR). Six different configurations viz. N1, N2, N3, N4, N5 and N6 were studied to reveal the effect of N-impurity on tunnelling dependent electron transport. It is predicted that the magnitude of current through these disconnected ZGNR devices is a function of tunnelling width, however, the qualitative behavior is quite similar. Further, a negative differential resistance (NDR) was observed for pristine nanoribbons which revokes upon N doping except for N3 configuration. The magnitude of tunnelling current is governed by the position of N impurities and can be further enhanced via selective doping of N atoms in the disconnected edges of ZGNR. Moreover, while operating in low bias regime (below 0.5 V), all the considered structures exhibit linear I V characteristics. Present findings may find applications in upcoming organic devices working on tunnelling phenomena. Graphical abstract Unlabelled Image Highlights • Current in disconnected zigzag graphene nanoribbons (DZGNR) is governed by tunnelling phenomena. • Pristine DZGNR shows negative differential resistance (NDR) effect. • N-doping induces n-type character in DZGNR. • Enhanced current could be obtained via selective N doping. [ABSTRACT FROM AUTHOR]