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Conducting channel migration depending on the thickness of 2D multilayers has been demonstrated theoretically and experimentally by ascribing it to the high interlayer barrier and thickness-dependent carrier mobility via an electrostatic gate and drain bias. However, the unique charge carrier transport feature is significantly suppressed when a high contact resistance is exhibited at the metal-to-2D semiconducting multilayers, in addition to the inherent tunneling barrier between neighboring layers. Herein, we report strong channel access contact resistance effects on the vertical carrier density profile and surface trap density along the thickness of WSe2 multilayer transistors. For the constructed top-contact electrodes demonstrating pseudo-ohmic behavior, we observed clear double humps in the second derivative of the transconductance (dgm) curves, implying conducting channel migration along the c-axis of the WSe2 multilayers, regardless of the drain bias (VD) conditions. Meanwhile, at the bottom-contact electrodes, demonstrating a relatively high contact resistance effect, the second hump of dgm exclusively appears at high VD regimes (3.0 V ≤ VD), signaling the restricted channel migration caused by poor contact quality, even in identical WSe2 multilayers. We further confirmed this distinct feature in dgm curves by connecting the top and bottom electrodes to support our observations. Furthermore, low-frequency noise measurements were performed to determine the surface trap density of the supporting dielectrics and the relevant carrier scattering mechanism. Our study provides valuable insight into the effects of contact resistance on carrier transport and the scattering mechanism in WSe2 multilayer transistors, shedding light on the optimization of device performance and contact quality. [ABSTRACT FROM AUTHOR]

In this study, it is demonstrated that CsPbBr3 perovskite nanocrystals (NCs) can enhance the overall performances of photomultiplication‐type organic photodiodes (PM‐OPDs). The proposed approach enables the ionic‐polarizable CsPbBr3 NCs to be evenly distributed throughout the depletion region of Schottky junction interface, allowing the entire trapped electrons within the depletion region to be stabilized, in contrast to previously reported interface‐limited strategies. The optimized CsPbBr3‐NC‐embedded poly(3‐hexylthiophene‐diyl)‐based PM‐OPDs exhibit exceptionally high external quantum efficiency, specific detectivity, and gain–bandwidth product of 2,840,000%, 3.97 × 1015 Jones, and 2.14 × 107 Hz, respectively. 2D grazing‐incidence X–ray diffraction analyses and drift–diffusion simulations combined with temperature‐dependent J–V characteristic analyses are conducted to investigate the physics behind the success of CsPbBr3‐NC‐embedded PM‐OPDs. The results show that the electrostatic interactions generated by the ionic polarization of NCs effectively stabilize the trapped electrons throughout the entire volume of the photoactive layer, thereby successfully increasing the effective energy depth of the trap states and allowing efficient PM mechanisms. This study demonstrates how a hybrid‐photoactive‐layer approach can further enhance PM‐OPD when the functionality of inorganic inclusions meets the requirements of the target device. [ABSTRACT FROM AUTHOR]

The present work reports fabrication of polyaniline (PANI)-porous silicon (PS) heterostructure obtained by PANI coating on PS using vacuum coating deposition technique. Electrical properties are studied through the measurement of current (I)–voltage (V) characteristics. Some parameters (viz. ideality factor, barrier height, series resistance) are calculated from the I-V plots. Fitting of these curves is done with the thermionic emission (TE) and Cheung's method. It is found that Cheung's method provides better knowledge about the heterostructure in terms of series resistance. The heterostructure comes out as an electrically active material with minimal series resistance of 23.53 kΩ resulting high-driven electric current. The I–V of the heterostructure follows space charge limited conduction (SCLC) mechanism due to the presence of traps or imperfection in the heterostructure. Prior to electrical measurement the device is characterized through field emission scanning electron microscope (FESEM), UV–vis–NIR reflectance, photoluminescence (PL) and Raman spectra for morphological and optical properties. FESEM shows the modified PS structure after PANI deposition revealing short-chained PANI molecules due to thermal treatment. UV–vis-NIR shows lower reflectance of the heterostructure due to impregnation of PANI to the pores of PS resulting change in refractive index. PANI-PS shows quenched PL peak. Raman spectra complement the FESEM results. [ABSTRACT FROM AUTHOR]

Mn2+-doped perovskites nanocrystals (NCs) have already been extensively studied in fascinating optical, electronic, and magnetic properties. Such interesting traits make them paid considerable attention in light emitting diodes, solar cells, etc. However, the underlying thermal and photophysical processes governing the overall charge carrier dynamics in Mn-doped NCs are far from clear. Herein, trap concentration and thermalization-dependent optical properties of Mn–Cu co-doped CsPbCl3 NCs were investigated via using steady-state, time-resolved PL spectra, variable-temperature PL spectra, and ultrafast transient absorption spectra. The combined experimental and theoretical studies reveal that Cu2+, as an effective hole trap, can trap the holes from Mn2+ and emit the holes to Mn2+ level at lighter and higher doping, respectively. Moreover, this hole trap is highly thermally sensitive, which is responsible for the abnormal thermal effect of Mn2+ emission with increasing temperature. These findings demonstrate an approach of charge regulation through ion doping, which is meaningful for fabricating efficient photoelectric materials and devices. [ABSTRACT FROM AUTHOR]

Single‐phase zinc sulphide (ZnS) quantum dots were synthesized by hydrothermal method without using any capping agent. X‐ray power diffraction, transmission electron microscopy, and ultraviolet‐visible spectroscopy were used to characterize the structure, size, surface states. Photoluminescence properties of ZnS quantum dots were studied to apply it as fluorescence sensor. The results showed that the crystal structure of ZnS quantum dots was a cubic zinc blende, and their average diameter was about 3.5 nm. A strong broad band cantered at about 320 nm was observed in the excitation spectrum of ZnS quantum dots. Their emission spectrum peaking at about 408 nm, was due mostly to the trap‐state emission. We used cadmium as fluorescence super quencher to detect the presence of cadmium. The relative integrated emission intensity of ZnS quantum dots decreased as the amount of Cd increased. That 408 nm emitted radiation was then used to detect the presence of fluoranthene, a potential carcinogen, present in solution. The novelty of the process is the use of water as a solvent for synthesis, without using any capping agent by slow hydrothermal process. [ABSTRACT FROM AUTHOR]

Organic solar cell (OSC) devices suffer from low power conversion efficiency (PCE) due to deep trap states that absorb photogenerated charges, act as recombination centers, and reduce charge collection. To further improve the PCE, an optimized hole transport layer (HTL) must be engineered for efficient hole transport and reduced deep trap states. A hybrid HTL consisting of organic and inorganic materials was formed using a combination of CuO nanoparticles (NPs) having an average size of 50 nm and poly(3-hexylthiophene) (P3HT). The hybrid HTL was used in the fabrication and characterization of an inverted OSC device structure. In consequence, the incorporation of CuO-NPs into the P3HT resulted in an increase of 8.66% in photocurrent density. Additionally, the PCE increased from 3.77 to 4.22% while the open circuit voltage (Voc) was maintained. The higher hole mobility obtained for the optimum device using the charge extraction by increasing voltage (CELIV) measurement was 8.47 × 10− 4 cm2 V− 1 s− 1. This highlights the potential of designing novel organic solar cells with inorganic nanoparticles, offering enhanced performance and efficiency. [ABSTRACT FROM AUTHOR]

Since the launch of the Fermi mission in 2008, it has become possible to study high-energy solar γ -rays with an unprecedented imaging capability. In particular, the position of the > 100 MeV γ -ray source can shed light on the origin of high-energy protons that is still controversial. However, the imaging of solar γ -ray sources with the Fermi Large Area Telescope (LAT) is a complex multi-stage process influenced by a number of factors and instrumental effects, which is difficult to fully comprehend a priori. The SOL2014-09-01 behind-the-limb event was significant, for which the γ -ray source position was not firmly established at once. Following the methodology outlined by the Fermi/LAT team, we estimated the proton power-law indices and γ -ray centroid positions at two temporal intervals of this event, separated by one hour. Our estimates for the first interval are comparable to estimates recently updated by the Fermi/LAT team, thereby confirming the consistency of the analysis applied. Although, in the second interval, corresponding to the decay phase of the flare, the proton power-law index clearly hardened, the presumable position of the fading γ -ray source remained unchanged. Its constancy in both temporal intervals and its proximity to the bases of long coronal loops connected to the flare site support the flare origin of high-energy protons injected into these loops along with electrons and trapped there for a long time. Our experience analyzing Fermi/LAT data clarifies their complex handling and will hopefully benefit the solar community in their wider use. [ABSTRACT FROM AUTHOR]

The aim of this article is to show that it is possible to rapidly estimate the activation energies of electron traps in AlInN/GaN transistors operating at room temperature by combining pulsed electrical measurements with photoionization techniques using infrared illumination. This technique avoids the time‐consuming task of performing electrical measurements at different temperatures to determine the activation energies of the electron traps using Arrhenius laws. Thus, a deep level at 1.3 eV is detected and attributed to the presence of carbon in GaN buffer of the component. Moreover, we have highlighted that the trapping effect can be screened when the transistors are biased with a high drain‐source voltage during pulsed measurements. [ABSTRACT FROM AUTHOR]

[Display omitted] • Ball milling method is applicable to general synthesis of SACs for different metals. • Zn SACs as electron traps could significantly promote charge separation of g-C 3 N 4. • The single-atom catalytic site (Zn) leads to enhanced photocatalytic activity. • The photocatalytic CO 2 RR to CO over Zn-g-C 3 N 4 achieves 100 % selectivity. The major challenge in the photocatalytic reduction of CO 2 is to achieve high conversion efficiency while maintaining selectivity for a single product. Photocatalysts containing single-metal Cu2+ with 3d9 and Zn2+ with 3d10 on g-C 3 N 4 were prepared using a high-energy ball mill. Single-atom Zn inner electron configuration is stable (3d10) and the peripheral empty orbitals act as electron traps to trap photo-generated electrons and improve the efficiency of charge separation; Zn is an active site to enhance the adsorption and activation of CO 2. The stable electron configuration can reduce the energy required for the overall reaction and increase the activity while changing the reaction pathway to form CO. As a result, the 0.5 mol% Zn/g-C 3 N 4 (Zn-CN-0.5) photocatalyst achieves ∼100 % selectivity for the photocatalytic reduction of CO 2 to CO at a rate of ∼21.1 μmol·g−1·h−1. In contrast, the 0.5 mol% Cu/g-C 3 N 4 (Cu-CN-0.5) photocatalyst with an unstable electronic structure does not exhibit high selectivity. [ABSTRACT FROM AUTHOR]

Electron-acoustic waves (EAWs) as well as electron-acoustic solitary structures play a crucial role in thermalization and acceleration of electron populations in Earth's magnetosphere. These waves are often observed in association with whistler-mode waves, but the detailed mechanism of EAW and whistler wave coupling is not yet revealed. We investigate the excitation mechanism of EAWs and their potential relation to whistler waves using particle-in-cell simulations. Whistler waves are first excited by electrons with a temperature anisotropy perpendicular to the background magnetic field. Electrons trapped by these whistler waves through nonlinear Landau resonance form localized field-aligned beams, which subsequently excite EAWs. By comparing the growth rate of EAWs and the phase mixing rate of trapped electron beams, we obtain the critical condition for EAW excitation, which is consistent with our simulation results across a wide region in parameter space. These results are expected to be useful in the interpretation of concurrent observations of whistler-mode waves and nonlinear solitary structures and may also have important implications for investigation of cross-scale energy transfer in the near-Earth space environment. [ABSTRACT FROM AUTHOR]

In planetary radiation belts, the Kennel‐Petschek flux limit is expected to set an upper limit on trapped electron fluxes at 80–600 keV in the presence of efficient electron loss through pitch‐angle diffusion by whistler‐mode chorus waves generated around the magnetic equator by the same 80–600 keV electron population. Comparisons with maximum measured fluxes have been relatively successful, but several key assumptions of the Kennel‐Petschek model have not been experimentally tested. The Kennel‐Petschek model notably assumes an exponential growth of chorus waves as the trapped electron flux increases, and a fixed maximum wave power gain of about 3. Here, we describe a method for inferring the near‐equatorial wave power gain using only measurements of trapped, precipitating, and backscattered electron fluxes at low altitude. Next, we make use of Electron Losses and Fields Investigation (ELFIN) CubeSats measurements of such electron fluxes during two moderate geomagnetic storms with sustained electron injections to infer the corresponding chorus wave power gains as a function of time, energy, and equatorial trapped electron flux. We show that wave power increases exponentially with trapped flux, with a wave power gain roughly proportional to the theoretical linear convective gain, and that the maximum inferred gain near the upper flux limit is roughly 10, with a factor of 2 uncertainty. Therefore, two key theoretical underpinnings of the Kennel‐Petschek model are borne out by the present results, although the strong inferred gains should correspond to higher flux limits than in traditional estimates. Key Points: A method for inferring equatorial wave power gain from low altitude electron flux measurements based on quasi‐linear theory is describedThe inferred chorus wave power gain increases roughly linearly with equatorial 180–300 keV trapped electron flux during moderate stormsInferred chorus wave power gains typically reach 10 near the upper flux limit [ABSTRACT FROM AUTHOR]

We performed dry oxidation on n-type silicon carbide (SiC), followed by annealing in diluted N2O, and subsequently fabricated n-type MOS structures. The study aimed to investigate the impact of different annealing times on the trap charges near the SiC/SiO2 interface and the reliability of the gate dielectric. Capacitance-voltage (C-V) and current-voltage (I-V) measurements of the n-type MOS revealed that increasing the annealing time with N2O effectively reduces the density of electron traps near the SiC/SiO2 interface, mitigates the drift in flat-band voltage and enhances the oxide breakdown field strength. However, excessive annealing time leads to an increase in the flat-band voltage drift of the MOS, resulting in premature oxide breakdown. Using the optimized annealing conditions, we fabricated n-type LDMOSFETs and obtained the threshold voltage (Vth), field-effect mobility (μFE) and specific on-resistance (Ron-sp) from the transfer curve (Id-Vg) and output curve (Id-Vd) measurements. The research findings provide valuable insights for the gate oxidation process of SiC. [ABSTRACT FROM AUTHOR]

A critical stage in developing high-density memristors is addressing the sneak current within the crossbar architecture. One of the effective strategies to endow the memristive cell with the ability to prevent sneak currents when it is in a low resistance state is to give it an inherent diode, known as a self-rectifying memristive cell. This study demonstrates the Schottky diode inside the MAPbI3-based memristive cell, a consequence of its interaction with the tungsten (W) electrode. The performance of memory devices is reliable with low-voltage operation, a resistance window having over ten of magnitude, and the retention time remains over 104 s. Prominently, the self-rectifying behavior is sustainable over 150 cycles and exhibits a rectification ratio of approximately 102 times. Density functional theory calculation reveals the presence of unoccupied gap states on an interfaced MAPbI3 surface, serving as electron trapping states during the charge transport across the W/MAPbI3 Schottky interface. Consequently, the conduction mechanism is primarily governed by an interfacial-controlled model, notably Schottky emission. This improvement promises to eliminate sneak currents in future crossbar array fabrication. [ABSTRACT FROM AUTHOR]

In this paper, we report on the radio-photoluminescence (RPL) properties and RPL center formation mechanism in Ag-doped Na-Al borate glass (BG:Ag). In BG:Ag, broad emission bands at 550-800 and 450-800 nm with excitation wavelengths at 320 and 360 nm appeared after X-ray irradiation, respectively. The electron spin resonance (ESR) signal intensity of Ag2+ and Ag2+ increased with absorption dose. These results suggest that BG:Ag exhibits RPL from Ag2+ and Ag2+. Furthermore, RPL emission bands and the ESR signals of Ag2+ and Ag2+ disappeared after heating at 773 K for 1 h. These results indicate that RPL centers can be eliminated by heating and that BG:Ag is a candidate reusable RPL material. On the basis of the variation of the ESR spectra with time from immediately after irradiation, we assumed the following RPL center formation mechanism. First, electron-hole pairs are generated by ionizing radiation. Some of the electrons are trapped at Ag+ and form Ag0. Subsequently, Ag2 + ions are formed by the association of Ag+ and Ag0. On the other hand, holes are trapped at the boronoxygen network to form a boron oxygen hole center (BOHC). Subsequently, the trapped holes transfer to Ag+ from BOHC and form Ag2+. [ABSTRACT FROM AUTHOR]

The flexible near‐infrared (NIR) organic photodetector is an essential prerequisite for the next‐generation visual system for accurate information identification. However, prevailing limitations in NIR organic photodetectors, including high noise, weak responsivity, and low detectivity, directly impede the translation to practical applications. Herein, ultranarrow bandgap acceptors, featuring a 2D highly electron‐donating central core (DTPC), named as YZ and YZ1, are designed and synthesized for NIR organic photodetectors. It is found that the introduction of highly rigid DTPC effectively reduces energetic disorder in active films. Moreover, extending the end conjugation not only broadens the absorption spectrum but also diminishes trap states and improves charge transport. Consequently, the YZ1‐based organic photodetector exhibits an impressive detection range from 300 to 1050 nm with a high responsivity of 0.27 A W−1 at 1000 nm and specific detectivity of 9.24 × 1013 Jones, comparable to commercial silicon photodiodes. Inspired by biological eyes, large‐area parallelly independent photodetector arrays (2000 pixels) for an artificial vision system are fabricated, which enables a clear matter identification in the NIR region. These findings and results simultaneously provide critical insights into molecular design and bridge the gap between material science and device engineering, accelerating the application of NIR organic photodetectors in next‐generation wearable optoelectronics. [ABSTRACT FROM AUTHOR]

Solar hydrogen production at a high efficiency holds the significant importance in the age of energy crisis, while the micro‐environment manipulation of active sites on photocatalysts plays a profound role in enhancing the catalytic performance. In this work, a series of well‐defined single‐site Ni‐grafted TiO2 photocatalysts with unique and specific coordination environments, 2,2′‐bipyridine‐Ni−O−TiO2 (T−Ni Bpy) and 2‐Phenylpyridine‐Ni−O−TiO2 (T−Ni Phpy), were constructed with the methods of surface organometallic chemistry combined with surface ligand exchange for visible‐light‐induced photocatalytic hydrogen evolution reaction (HER). A prominent rate of 33.82 μmol ⋅ g−1 ⋅ h−1 and a turnover frequency of 0.451 h−1 for Ni are achieved over the optimal catalyst T−Ni Bpy for HER, 260‐fold higher than those of Ni−O−TiO2. Fewer electrons trapped oxygen vacancies and a larger portion of long‐lived photogenerated electrons (>3 ns, ~52.9 %), which were demonstrated by the electron paramagnetic resonance and femtosecond transient IR absorption, correspond to the photocatalytic HER activity over the T−Ni Bpy. The number of long‐lived free electrons injected from the Ni photoabsorber to the conduction band of TiO2 is one of the determining factors for achieving the excellent HER activity. [ABSTRACT FROM AUTHOR]

Due to its short radiation length, moderate light output (8000‐9000 photons/MeV), high density (7.13 g cm−3), and non‐hygroscopicity, etc., Bi4Ge3O12 (BGO) material has been widely utilized as an advanced scintillator for irradiation detection. However, pure BGO cannot meet the requirements for future physics experiments and state‐of‐art industrial facilities coupled with a silicon photomultiplier (SiPM) due to its slow response time, poor radiation resistance, and excessive light output. Herein, a Ce‐doping strategy is reported for efficiently improving the overall performance (e.g., irradiation resistance, decay time, radioluminescence, and light output) of BGO that can be expectedly applied in future high energy physics detection. Ce‐doped BGO (BGO:Ce) displays higher radiation resistance ability under 10 h UV irradiation (97% of original) and a faster fluorescence lifetime (269 ns), superior to pure BGO. Furthermore, BGO:Ce shows ≈30% luminescence intensity of pure BGO, well eliminating the oversaturation of SiPM coupled with scintillation detectors. Theoretical calculations imply that an intense competition between electron or hole traps and Ce ions (Ce3+, Ce4+) can effectively reduce the concentration of color centers, thus enhancing irradiation resistance ability. [ABSTRACT FROM AUTHOR]

Photocatalytic H 2 evolution requires excellent charge separation and fast surface electron injection, whereas it is difficult to achieve with a single semiconductor catalyst. Herein, we present a simple two-step hydrothermal method for coupling metalloid CoS 2 nanospheres with CaIn 2 S 4 micro-flowers, which exhibits a 6-fold increase in the photocatalytic hydrogen evolution rate as bare CaIn 2 S 4. This activity enhancement surpasses that of noble metal (Pt or AuCu) modified CaIn 2 S 4. During five runs of photocatalytic tests, the composite photocatalysts maintain high photostability, without significant changes in crystal structure or morphology. The charge transfer at CoS 2 /CaIn 2 S 4 interface is revealed by synchronous illumination X-ray photoelectron spectroscopy, surface photovoltage spectrum and DFT calculation. According to the mechanism study, it shows that metallic CoS 2 can act as electron traps to speed up electron transfer due to the formation of intimate CoS 2 /CaIn 2 S 4 heterojunctions, while at the same time CoS 2 can serve as active centers to catalytic the water reduction into H 2 molecules. Overall, we propose a simple route to modify a semiconductor photocatalyst that can result in multiple distinct effect including improved charge separation and injection efficiency. [Display omitted] • CoS 2 nanoparticles were deposited on the surface of CaIn 2 S 4 micro-flowers. • 5 wt% CoS 2 cocatalyst coupled with CaIn 2 S 4 shows the highest H 2 evolution rate (960 μmol g−1 h−1). • The AQE of the sample of 5 wt% CoS 2 /CaIn 2 S 4 reaches 3.2% at 480 nm. • Charge transfer process of CoS 2 /CaIn 2 S 4 was elucidated in detail. [ABSTRACT FROM AUTHOR]

A theoretical account of some of the most likely hydrogen-related reactions with impurities in n- and p-type solar-grade silicon is presented. These include reactions with dopants and carbon, which are relevant in the context of lifetime degradation of silicon solar cells, most notably of light- and elevated temperatureinduced degradation of the cells. Among the problems addressed, a comparative study of acceptor-enhanced dissociation of hydrogen molecules in B- and Gadoped material, their subsequent reaction steps toward formation of acceptor-- hydrogen pairs, the proposal of mechanisms which explain the observed kinetics of photo-/carrier-induced dissociation of PH and CH pairs in n-type Si, analysis of reactions involving direct interactions between molecules with P and C, and the assignment of several electron and hole traps with detailed atomistic- and wavefunction-resolved models is highlighted. [ABSTRACT FROM AUTHOR]

In this paper, a low dose X-ray induced long afterglow luminescent phosphor Sr 3 MgSi 2 O 8 :Pr3+ has been reported. The structure analysis shows the as-prepared samples possess good crystallinity and the emitting center Pr3+ is more likely to occupy the lattice position of Sr2+ due to their similar ionic radius. And under 471.1 nm excitation, Sr 3 MgSi 2 O 8 :Pr3+ shows bright visible lights peaked at 545.5, 617.1 and 648.6 nm, respectively, corresponding to the transitions of 3P 0 →3H 5 , 3P 0 →3H 6 and 3P 0 →3F 2 of Pr3+. After the X-ray irradiation, this phosphor shows strong ultraviolet C (291.7 nm), blue (493.2 nm) and red lights (617.1 nm). More important, only 5 s X-ray irradiation X-ray irradiation can easily charge Sr 3 MgSi 2 O 8 :Pr3+ to produce 5400 s afterglow emission. Even after 5400 s, its afterglow emissions still remain strong, which is about 20 times of the background intensity. The thermoluminescent results indicate that Sr 3 MgSi 2 O 8 possesses a high absorption rate for X-rays and thus X-ray irradiation can excite the host to produce large number of electrons, Secondary electron, which would rapidly fill up the traps and thus produce excellent long afterglow luminescence. In addition, the existing suitable traps with 0.76 eV trap depth are also favorable for persistent luminescence at room temperature. Thus, Sr 3 MgSi 2 O 8 :Pr3+ is confirmed to be a very efficient low dose X-ray induced long afterglow luminescent phosphor. [ABSTRACT FROM AUTHOR]

The presence of surface trap states (STSs) is one of the key factors to affect the electronic and optical properties of quantum dots (QDs), however, the exact mechanism of how STSs influence QDs remains unclear. Herein, we demonstrated the impact of STSs on electron transfer in CdSe QDs and triplet-triplet energy transfer (TTET) from CdSe to surface acceptor using femtosecond transient absorption spectroscopy. Three types of colloidal CdSe QDs, each containing various degrees of STSs as evidenced by photoluminescence and X-ray photoelectron spectroscopy, were employed. Time-resolved emission and transient absorption spectra revealed that STSs can suppress band-edge emission effectively, resulting in a remarkable decrease in the lifetime of photoelectrons in QDs from 17.1 ns to 4.9 ns. Moreover, the investigation of TTET process revealed that STSs can suppress the generation of triplet exciton and effectively inhibit band-edge emission, leading to a significant decrease in TTET from CdSe QDs to the surface acceptor. This work presented evidence for STSs influence in shaping the optoelectronic properties of QDs, making it a valuable point of reference for understanding and manipulating STSs in diverse QDs-based optoelectronic applications involving electron and energy transfer. [ABSTRACT FROM AUTHOR]

In this work, the concentric structure of MIS tunnel diodes with coupling effect was explored for memory application. The thickness of the charge storage layer (Al2O3/SiO2) and annealing temperature were controlled to result in an efficient charge trapping with electrons from the substrate. This led to a significant reduction in operation time. In addition, it was found that the signal of non-uniform charge trapping at the device edge could be amplified (about three times) in the tunneling current of nearby MIS TD through the coupling effect. This phenomenon was initially observed and subsequently validated through TCAD simulation. Utilizing the coupling effect and the non-uniform charge storage, the proposed device's operating window is 1 V, with an on/off ratio of approximately 100. Furthermore, it exhibits small cycle-to-cycle variation (3%) and low power consumption. [ABSTRACT FROM AUTHOR]

Diamondoids form a molecular class of cage-like structures and serve as a link between small, cyclic hydrocarbons and bulk nanodiamonds. Comparisons have been made between the infrared spectra of diamondoids and unidentified infrared emission bands seen in the spectra of certain stars with circumstellar disks. It is also suggested that their radical cations may contribute to features in the largely unassigned diffuse interstellar bands due to their low ionisation energy and absorption in the visible range. However, the optical spectra of these cations have only recently begun to be measured experimentally, which is required for astronomical identification. Herein, we present the first optical spectrum of the 1-cyanoadamantane radical cation (C11H15N, AdaCN+) between 275 and 1200 nm. The spectrum is obtained by electronic photodissociation (EPD) of mass-selected ions generated by electron ionisation in a tandem mass spectrometer coupled to a cryogenic trap held at 5 K. Experimental results are interpreted by (time-dependent) density functional theory calculations. The dominant fragmentation channels are HCN loss at low energies and C4H6N loss at energies above 2.9 eV. The EPD spectrum reveals broad bands that are rationalised by lifetime broadening and Franck-Condon congestion arising from geometric changes upon excitation. The astrophysical implications are discussed. [ABSTRACT FROM AUTHOR]

The physical unclonable functions (PUFs) are novel cryptographic primitives in modern hardware security systems. Compared with traditional alternatives based on digital keys and non-volatile memory (NVM), the PUF system shows great unclonability, high efficiency, and physical attack resilience. However, the conventional PUF design suffers from weak machine learning immunity, high storage overhead, and unreliability, making it difficult to implement in the Internet of Things (IoT) and edge computing applications. This paper presents a new PUF design that could solve the proposed obstacles. By utilizing the emission probability of traps commonly found in nano-scaled transistors, a model-based PUF system with strong machine learning resistance could be achieved. This PUF design, called Prob-PUF, needs fewer challenge-response pairs (CRPs) space and reveals superior resistance to modeling attacks due to the mixture of stable/random bits in its output response. Moreover, the Prob-PUF system could reach a high level of uniqueness and robustness, making it a potential candidate for future cryptographically secured protocols within the IoT. [ABSTRACT FROM AUTHOR]

In this paper, the degradation behaviors of the ferroelectric gate Gallium nitride (GaN) high electron mobility transistor (HEMT) under positive gate bias stress are discussed. Devices with a gate dielectric that consists of pure Pb(Zr,Ti)O3 (PZT) and a composite PZT/Al2O3 bilayer are studied. Two different mechanisms, charge trapping and generation of traps, both contribute to the degradation. We have observed positive threshold voltage shift in both kinds of devices under positive gate bias stress. In the devices with a PZT gate oxide, we have found the degradation is owing to electron trapping in pre-existing oxide traps. However, the degradation is caused by electron trapping in pre-existing oxide traps and the generation of traps for the devices with a composite PZT/Al2O3 gate oxide. Owing to the large difference in dielectric constants between PZT and Al2O3, the strong electric field in the Al2O3 interlayer makes PZT/Al2O3 GaN HEMT easier to degrade. In addition, the ferroelectricity in PZT enhances the electric field in Al2O3 interlayer and leads to more severe degradation. According to this study, it is worth noting that the reliability problem of the ferroelectric gate GaN HEMT may be more severe than the conventional metal–insulator–semiconductor HEMT (MIS-HEMT). [ABSTRACT FROM AUTHOR]

Lead sulfide (PbS) colloidal quantum dot (CQD) photodiodes integrated with silicon‐based readout integrated circuits (ROICs) offer a promising solution for the next‐generation short‐wave infrared (SWIR) imaging technology. Despite their potential, large‐size CQD photodiodes pose a challenge due to high dark currents resulting from surface states on non‐passivated (100) facets and trap states generated by CQD fusion. In this work, we present a novel approach to address this issue by introducing double‐ended ligands that supplementally passivate (100) facets of halide‐capped large‐size CQDs, leading to suppressed bandtail states and reduced defect concentration. Our results demonstrate that the dark current density is highly suppressed by about an order of magnitude to 9.6 nA cm−2 at −10 mV, which is among the lowest reported for PbS CQD photodiodes. Furthermore, the performance of the photodiodes is exemplary, yielding an external quantum efficiency of 50.8% (which corresponds to a responsivity of 0.532 A W−1) and a specific detectivity of 2.5 × 1012 Jones at 1300 nm. By integrating CQD photodiodes with CMOS ROICs, the CQD imager provides high‐resolution (640 × 512) SWIR imaging for infrared penetration and material discrimination. [ABSTRACT FROM AUTHOR]

The effects of proton irradiation on CMOS Single-Photon Avalanche Diodes (SPADs) are investigated in this article. The I–V characteristics, dark count rate (DCR), and photon detection probability (PDP) of the CMOS SPADs were measured under 30 MeV and 52 MeV proton irradiations. Two types of SPAD, with and without shallow trench isolation (STI), were designed. According to the experimental results, the leakage current, breakdown voltage, and PDP did not change after irradiation at a DDD of 2.82 × 108 MeV/g, but the DCR increased significantly at five different higher voltages. The DCR increased by 506 cps at an excess voltage of 2 V and 10,846 cps at 10 V after 30 MeV proton irradiation. A γ irradiation was conducted with a TID of 10 krad (Si). The DCR after the γ irradiation increased from 256 cps to 336 cps at an excess voltage of 10 V. The comparison of the DCR after proton and γ-ray irradiation with two structures of SPAD indicates that the major increase in the DCR was due to the depletion region defects caused by proton displacement damage rather than the Si-SiO2 interface trap generated by ionization. [ABSTRACT FROM AUTHOR]

We have calculated the time constants of the electron dynamics in traps in a metal–insulator–metal (MIM) plasmonic structure. Because of electron relaxation in metal, the surface plasmon polaritons decays into hot electrons near the surface of the metal, which facilitates the trap of electrons in the interfacial layer of the dielectric. We have calculated the capture and emission times separately as the electron does not follow the same mechanisms with the capture process when it is emitted from a trap at the metal/oxide interface. We have developed a quasi-two-dimensional treatment that has been modified from a previously used semiconductor/oxide junction by using Bardeen's function to calculate the capture time. Various parameters including trap's distance from the interface, temperature, voltage bias, and spectral nature of the hot electrons' energy distribution influence the interaction between a plasmonic hot electron and a neutral near-interface trap in the capture process. On the one hand, the emission time is independent of the capture time, and it is determined by the tunneling time to the metal depending on the temperature and the energy difference between the trap energy levels (ground and excited states). We have showed that a wide range of capture times from seconds to picoseconds is possible for an interfacial trap at the room temperature due to the spectral energy distribution of hot electrons and dependence of the capture process on the losses in metals. On the other hand, the temperature plays the dominant role in the emission time. For the trap with 250 meV energy difference between its levels, the emission time is in the range of picosecond at room temperature. Therefore, the MIM plasmonic device can respond to a wide range of ac voltage frequencies including the ultra-fast domain. These interesting findings are useful to understand the ac response of the MIM plasmonic devices with applications in integrated photonics and ultra-fast optoelectronics. [ABSTRACT FROM AUTHOR]

Electron paramagnetic resonance (EPR) is used to establish models for electron traps in Ag-doped lithium tetraborate (Li2B4O7) crystals. When exposed at room temperature to ionizing radiation, electrons are trapped at interstitial Ag+ ions and holes are trapped at Ag+ ions on Li+ sites. The trapped electrons occupy a 5s1 orbital on the interstitial Ag ions (some of the unpaired spin density is also on neighboring ions). Three EPR spectra are assigned to electrons trapped at interstitial Ag ions. Their g values are near 1.99 and they have resolved hyperfine structure from 107Ag and 109Ag nuclei. The spectrum representing the largest concentration of trapped electrons has the unpaired spin shared by the interstitial Ag ion and an adjacent boron ion at its regular lattice site. A 10B enriched crystal verifies this assignment and an analysis of spin-Hamiltonian parameters yields information about the Ag and B orbitals occupied by the unpaired spin. The second spectrum has the unpaired spin shared equally by two Ag ions, one at an interstitial site and the other at an adjacent Li site. The third spectrum has a large Ag hyperfine interaction and a weak Li interaction. Optical absorption bands associated with the trapped electrons are observed between 225 and 500 nm. Thermal release of electrons from these traps is responsible for a prominent thermoluminescence peak near 150 °C, whereas optical release of the electrons at room temperature produces intense optically stimulated luminescence. Radiative recombination occurs at Ag2+ ions with emission peaking near 270 nm. [ABSTRACT FROM AUTHOR]

The threshold voltage (VT) is the most important parameter in semiconductor devices. To control the VT of the thin‐film transistors (TFTs), we propose heterojunction structure of p‐type Tellurium (Te) and n‐type Aluminum‐Doped Indium‐Zinc‐Tin‐Oxide (Al:IZTO) which acts as electron blocking layer and carrier transporting layer, respectively. We investigate the effect of adding the heterojunction layer on the Al:IZTO and demonstrate VT shift up to +20V by adjusting the thickness and single / double deposition of the heterojunction Te layer. [ABSTRACT FROM AUTHOR]

Graphitic carbon nitride (GCN) has attracted significant attention due to its excellent performance in photocatalytic applications. Non-metal doping of GCN has been widely used to improve the efficiency of the material as a photocatalyst. Using a combination of time-domain density functional theory with nonadiabatic molecular dynamics, we study the charge carrier dynamics in oxygen and boron doped GCN systems. The reported simulations provide a detailed time-domain mechanistic description of the charge separation and recombination processes that are of fundamental importance while evaluating the photovoltaic and photocatalytic performance of the material. The appearance of smaller energy gaps due to the presence of dopant states improves the visible light absorption range of the doped systems. At the same time, the nonradiative lifetimes are shortened in the doped systems as compared to the pristine GCN. In the case of boron doped at a carbon (B–C–GCN), the charge recombination time is very long as compared to the other two doped systems owing to the smaller electron–phonon coupling strength between the valence band maximum and the trap state. The results suggest B–C–GCN as the most suitable candidate among three doped systems studied in this work for applications in photocatalysis. This work sheds light into the influence of dopants on quantum dynamics processes that govern GCN performance and, thus, guides toward building high-performance devices in photocatalysis. [ABSTRACT FROM AUTHOR]

Degradation of InGaN–GaN LEDs has been the subject of intense investigations in the past few years. While current- and temperature-induced degradation processes have been described, the impact of photon-induced degradation has not been investigated in detail in the literature. This paper aims at improving the understanding of the mechanisms responsible for the degradation of the InGaN subject to high photon densities by stressing the devices under a high-intensity laser beam in open-circuit conditions (i.e., in the absence of external current). We analyzed the degradation by means of electrical, optical, and deep-level characterization techniques. First, we demonstrate the existence of optically induced degradation processes in GaN LEDs: from photoluminescence measurements, we observed a decrease in the luminescence after stress, more prominent in the region irradiated during stress. Second, we ascribe this effect to a decrease in internal quantum efficiency due to the generation of non-radiative defects within the active region. Third, by steady-state photocapacitance measurements, we reveal the presence of a shallow level with an energy of EC–2.2 eV, which can be ascribed to gallium vacancies and its complexes with oxygen and nitrogen and can be related to the increase in yellow luminescence. [ABSTRACT FROM AUTHOR]

Element doping can have a profound impact on the photoelectrochemical properties of quantum dots (QDs); nevertheless, the hitherto known information in this regard is mainly from the steady-state characterizations and remains lacking input from the dynamics perspective. Herein, we present a systematic scrutiny of the element doping-induced effects in Zn-doped CdTe QDs. By means of steady-state/time-resolved/temperature-dependent photoluminescence spectroscopy and ultrafast transient absorption spectroscopy, we reveal that the slight Zn-doping in CdTe QDs can greatly affect the involved carrier relaxation dynamics through a density-of-state modification for both near-band-edge and localized surface trap states. Furthermore, such slight doping is found to be quite significant in modulating the photoreduction efficiency (of particular relation to the localized surface trap states) as well as altering the involved relaxation/reaction activation energy and phonon effect in this QDs system. This work enriches our fundamental understanding of the element doping-induced surface/interface effects, from the dynamics perspective in particular, and, hence, offers helpful guidance for QDs-based photoelectrochemical design and optimization. [ABSTRACT FROM AUTHOR]

Understanding the properties of N-implanted β-Ga2O3 is fundamental for the optimization of doping and isolation structures based on gallium oxide. This paper reports an extensive analysis of the impact of thermal annealing on the concentration and properties of deep levels in N-implanted β-Ga2O3 Schottky barrier diodes by means of capacitance isothermal transient spectroscopy. Samples with annealing temperatures from 800 to 1200 °C were considered. The original results presented in this paper demonstrate the following: (a) The instability of current–voltage characteristics detected for all the samples under test can be attributed to the presence of three electron traps with activation energies of 0.6, 0.7, and 1 eV, consistent with previous reports in β-Ga2O3. (b) The detected traps are not the nitrogen level but intrinsic defects whose concentration is increased by the implantation process. (c) The concentration of deep levels decreases as the annealing temperature increases, demonstrating that the annealing process can effectively restore the quality of the material while keeping the conductivity decrease related to the presence of the nitrogen. Finally, (d) we demonstrate that the residual leakage and the turn-on voltage shift are correlated with the Arrhenius signature of the detected deep levels. An interpretation is proposed to explain the measurement results. [ABSTRACT FROM AUTHOR]

Kink effect is observed in Al 0.83 In 0.17 N/GaN high electron mobility transistor by measuring I D -V D S characteristics at a low sweep rate. It is inferred that the kink is induced due to the trapping/detrapping of charge carriers at deep levels present in the GaN buffer in the gate–drain access region. The detrapping of charge carriers from the deep levels is by the hot-electron-assisted mechanism. Two types of traps with activation energies, 0.29 eV (donor-like) and 0.57 eV (acceptor-like) were extracted by temperature-dependent transient drain current analysis. It is concluded that the deep-acceptor-like trap with a large emission time constant is responsible for the kink effect. [ABSTRACT FROM AUTHOR]

Cadmium zinc telluride (CZT) is an ideal material for room temperature nuclear radiation detection, but CZT crystals of high quality and low defects concentration are difficult to obtain. Therefore, in order to improve the performance of the CZT detector, the working conditions of the CZT detector could be appropriately changed to make the internal electric field of the CZT detector close to uniform distribution so as to improve the electron transport performance. In this paper, alpha induced transient charge analysis has been used to study the internal electric field of the CZT detector, and deep level defects in CZT were linked with internal electric field distribution. Based on the process, a variety of deep level defects on electron trapping and detrapping by changing the temperature, the output waveform change of charge sensitive preamplifier (the pulse height spectra for alpha radiation at different temperatures) was observed, and then the effects of deep level defects on electron mobility (μ e), electron transport time (T R), the internal electric field, and the electron collection efficiency of the CZT detector were analyzed. The experimental results indicated that the influence of deep level defects was a main factor to the internal electric field in the range of −140 to 40 °C. As the temperature rises, the influence of these defects weakens, μ e and electron collection efficiency both increase, and internal electric field distribution tends to be uniform. Moreover, with the further increasing temperature (−40 to 20 °C), μ e decreased and internal electric field distribution became fluctuating, but electron collection efficiency was basically unchanged, which suggested that the influence of lattice vibration in the range of −40 to 20 °C turned to be the main factor. The above conclusions demonstrated that although the CZT detector has excellent room temperature detection ability, room temperature was not its optimal working temperature due to the influence of high concentration deep level defects. At −20 °C, the CZT detector presented the highest electron collection efficiency and maximum which limited the influence of deep level defects on electron transport, performing the optimal properties. [ABSTRACT FROM AUTHOR]

Electrically active defects in carbon-doped GaN layers were studied with a metal/carbon-doped GaN (GaN:C)/Si-doped GaN (GaN:Si) MIS structure. The GaN:C layers were grown with three different carbon doping concentrations (NC). A semi-vertical metal/semi-insulator/n-type semiconductor (MIS) device was fabricated to perform deep-level transient spectroscopy (DLTS) measurements. Two electron traps E1 and E2 with energy level at EC − (0.22–0.31) eV and EC − (0.45–0.49) eV were observed. E1 and E2 are associated with a nitrogen vacancy VN-related defect in the strain field of extended defects and a nitrogen antisite defect, respectively. By changing the reverse bias voltage of the DLTS measurement, the location and relative defect concentration of the E1 and E2 traps could be verified. A dominant electron trap E3 with an unusual capture cross section was only observed in devices with an NC = 2 × 1019 cm−3 GaN:C layer. This may charge carriers from a defect band and lead to the charge redistribution in the GaN:C layer when forward biased. A hole trap H1 with energy level at EV + 0.47 eV was found for the pulse bias in the forward ON-state. H1 is suggested to correspond with the CN induced 0/+ donor level. By analyzing the schematic band diagrams across the MIS structure, the carrier transport and defect charging mechanisms underlying the DLTS transient measurements are illustrated. The identification of the trap states in the carbon-doped GaN with different NC gives further understanding on the carbon doping impact on electric characteristics of GaN power devices made on Si substrates. [ABSTRACT FROM AUTHOR]

Phototransferred thermoluminescence (PTTL) from BeO is reported. The conventional TL glow curve has five peaks, I–V, at 50, 182, 283, 437, and 535 °C when measured at 1 °C s−1 The dominant one is peak II. Only the first three reappear under phototransfer. Electron traps for peaks IV and V weakly contribute to the PTTL. The PTTL at peak III, supposedly associated with these weak donors, is counterintuitively intense. All PTTL peaks are affected by light-induced fading, thermal quenching, and all but peak II by thermal fading. The activation energy for thermal quenching was found as 0.56 ± 0.02 , 0.53 ± 0.05 , and 0.94 ± 0.07 eV using peaks I, II, and III, respectively. Electronic processes relevant in the PTTL of BeO are discussed. PTTL time-response profiles are analyzed using systems of coupled linear differential equations as well as by theoretical modeling. [ABSTRACT FROM AUTHOR]

The changes of electrical properties and deep trap spectra induced in n-type β-Ga2O3 by 1 GeV protons with a fluence of 4 × 1013 cm−2 were studied. The carrier removal rates were ∼100 cm−1 at this energy. For comparison, for 20 MeV proton irradiation at comparable fluences (5–10 × 1014 cm−2), the removal rate was ∼400 cm−1 for donor concentrations of 3 × 1016 cm−3 and ∼100 cm−1 for concentrations of <1016 cm−3. These removal rates were in stark contrast with modeling results that predicted the introduction rates of vacancies to be two orders of magnitude higher for 20 MeV protons. Measurements of deep electron and hole traps densities by deep level transient spectroscopy with electrical or optical injection (DLTS or ODLTS), and capacitance–voltage profiling under monochromatic light illumination showed that the 1 GeV proton irradiation resulted in the introduction of deep donors E2*(Ec-0.75 eV) and E3 (Ec-1 eV) and deep acceptors with optical ionization threshold near 2.3 eV producing a feature near 250 K in ODLTS and 3.1 eV with related ODLTS feature near 450 K. The total concentration of all deep traps was much lower than that necessary to explain the observed decrease in net donor density upon irradiation. The donor densities showed a nonuniform distribution in proton irradiated films with the concentration greatly decreased toward the surface. Possible reasons for the observed performance are discussed. [ABSTRACT FROM AUTHOR]

The changes of electrical properties and deep trap spectra induced in n-type β-Ga2O3 by 1 GeV protons with a fluence of 4 × 1013 cm−2 were studied. The carrier removal rates were ∼100 cm−1 at this energy. For comparison, for 20 MeV proton irradiation at comparable fluences (5–10 × 1014 cm−2), the removal rate was ∼400 cm−1 for donor concentrations of 3 × 1016 cm−3 and ∼100 cm−1 for concentrations of <1016 cm−3. These removal rates were in stark contrast with modeling results that predicted the introduction rates of vacancies to be two orders of magnitude higher for 20 MeV protons. Measurements of deep electron and hole traps densities by deep level transient spectroscopy with electrical or optical injection (DLTS or ODLTS), and capacitance–voltage profiling under monochromatic light illumination showed that the 1 GeV proton irradiation resulted in the introduction of deep donors E2*(Ec-0.75 eV) and E3 (Ec-1 eV) and deep acceptors with optical ionization threshold near 2.3 eV producing a feature near 250 K in ODLTS and 3.1 eV with related ODLTS feature near 450 K. The total concentration of all deep traps was much lower than that necessary to explain the observed decrease in net donor density upon irradiation. The donor densities showed a nonuniform distribution in proton irradiated films with the concentration greatly decreased toward the surface. Possible reasons for the observed performance are discussed. [ABSTRACT FROM AUTHOR]

In amorphous oxide semiconductors, rough interfaces influence transport in two main ways: changing the trap distributions and interface roughness scattering. Interface roughness scattering is expected to become important in high-mobility semiconductors in which charge transport takes place through a combination of trapping and band transport. Interface roughness scattering is quantitatively analyzed for amorphous oxide thin-film transistors (TFTs) within the framework of the Boltzmann transport equation. It is shown to be the main mobility limiting mechanism at room temperature under the conditions when carrier concentration is high and the interface is rough. The use of the precise extent of wavefunction overlap with the interface is important and the use of a finite potential barrier height at the insulator–semiconductor interface leads to more accurate calculations. The specific semiconductors considered are zinc tin oxide and indium gallium zinc oxide. It is shown that the consideration of interface roughness scattering can become important in evaluating transport in high-mobility TFTs. [ABSTRACT FROM AUTHOR]

We propose an analytical model to reproduce the non-monotonic instability of the threshold voltage in 4H-SiC MOSFETs submitted to a positive gate stress bias. Experimental analysis of the threshold voltage transients indicates that both electron and hole trappings take place in the gate dielectric or at the dielectric/semiconductor interface, responsible for a VTH increasing–decreasing–increasing pattern. At low/moderate stress fields (<7 MV/cm), the electron trapping kinetics responsible for a positive VTH shift are modeled by a rate equation considering a trapping-inhibition model, which explains the logarithmic degradation kinetics. In the high field regime (>8 MV/cm), we propose that electrons can tunnel through the SiO2, be accelerated by the high field, and generate holes through impact ionization (II) or anode hole injection. These holes are then trapped in the oxide, thus generating a negative VTH shift. This second process has an exponential time-dependency, as found through the analysis of the corresponding rate equations. The time constant of the positive VTH shift is evaluated as a function of stress voltage and temperature. The results indicate that the time constant is strongly dependent on the electric field (that accelerates electrons to generate holes), and not thermally activated, in agreement with theoretical considerations. [ABSTRACT FROM AUTHOR]

This paper proposes a method to extract deep-level trap states of the organic photodiode by capacitance–voltage (CV) measurement. The relationship between the trapped charge density and the surface potential can be determined by solving Poisson's equation, while employing Gauss's theorem to establish a correlation between the charge density and the CV characteristics. Consequently, deep-level trap states can be analytically obtained by the conventional CV measurement. Experimental results on P3HT:PCBM devices demonstrate that the deep trap distribution obtained by this method can be well connected with the capacitance–frequency method. Furthermore, our CV method yields a total trap concentration, which closely aligns with that obtained through Mott–Schottky relation. In conclusion, this method provides an effective approach for quantifying deep trap state density of organic photodiode. [ABSTRACT FROM AUTHOR]

Inorganic lead‐free halide perovskites, devoid of toxic or rare elements, have garnered considerable attention as photocatalysts for pollution control, CO2 reduction and hydrogen production. In the extensive perovskite design space, factors like substitution or doping level profoundly impact their performance. To address this complexity, a synergistic combination of machine learning models and theoretical calculations were used to efficiently screen substitution elements that enhanced the photoactivity of substituted Cs2AgBiBr6 perovskites. Machine learning models determined the importance of d10 orbitals, highlighting how substituent electron configuration affects electronic structure of Cs2AgBiBr6. Conspicuously, d10‐configured Zn2+ boosted the photoactivity of Cs2AgBiBr6. Experimental verification validated these model results, revealing a 13‐fold increase in photocatalytic toluene conversion compared to the unsubstituted counterpart. This enhancement resulted from the small charge carrier effective mass, as well as the creation of shallow trap states, shifting the conduction band minimum, introducing electron‐deficient Br, and altering the distance between the B‐site cations d band centre and the halide anions p band centre, a parameter tuneable through d10 configuration substituents. This study exemplifies the application of computational modelling in photocatalyst design and elucidating structure–property relationships. It underscores the potential of synergistic integration of calculations, modelling, and experimental analysis across various applications. [ABSTRACT FROM AUTHOR]

Silicon oxide based and aluminum gated MOS structures fabricated on n-type silicon are investigated after irradiation with low energy electrons in scanning electron microscope. The thermally stimulated current (TSC) technique in the temperature range from 80 K to 320 K revealed a number of the electron beam induced charge traps. With the help of the capacitance-voltage method, the traps revealed by the TSC were identified by their location (within dielectric, semiconductor or at the interface) and by their nature (trap for electrons or for holes). [ABSTRACT FROM AUTHOR]

Recently, novel 2D materials with fascinating characteristics are extensively applied to design/fabricate high‐activity and cost‐effective photocatalysts for solar‐driven fuels/chemicals generation. Among these 2D materials, HfS2 nanosheets (NSs) exhibit excellent features of large surface area, short bulk‐to‐surface distance, alterable band structures, and vast catalytic sites. Despite these features, no realistic experimental works on HfS2‐based materials are reported in photocatalysis field. Moreover, it is interesting but challenging to realize atomic‐scale engineering of compositions/structures for novel 2D materials and to relate these atomic‐scale characteristics with the element/space/time‐resolved charge kinetics of 2D materials‐based photocatalysts. Herein, for the first time, atomic‐scale defected HfS2 NSs are designed/synthesized. The as‐synthesized HfS2 NSs are combined with various photocatalysts to acquire novel HfS2‐TiO2, HfS2‐CdS, HfS2‐ZnIn2S4, and HfS2‐C3N4 composites, respectively. Among them, HfS2‐CdS exhibits the highest rate (5971 µmol g−1 h−1) on hydrogen (H2) evolution in triethanolamine aqueous solution, together with obviously‐enhanced rates on H2 (2419 µmol g−1 h−1) and benzaldehyde (5.11 mmol g−1 h−1) evolution in benzyl alcohol aqueous solution. Various state‐of‐art characterizations reveal the element/space/time‐resolved electron/hole kinetics in HfS2‐CdS composites, disclosing that these atomic‐scale S vacancies temporarily trapping electrons to facilitate spatiotemporal electron–hole separation/transfer. This work paves avenues to atomic‐scale design/synthesis of new 2D‐materials‐based photocatalysts for sunlight utilization. [ABSTRACT FROM AUTHOR]

High‐performance flexible photodetectors are urgently demanded for application in many emerging domains including flexible, wearable, portable, and stretchable optoelectronics. In this work, a highly efficient flexible photodetector made of a Ti3C2Tx MXene/pyramidal thin Si heterostructure is successfully fabricated. Thanks to the remarkable light trapping effect as confirmed by numerical modeling based on finite‐element method, the as‐constructed detector demonstrates excellent photoresponse performance in a broadband wavelength spectrum. The optimal responsivity, specific detectivity, and response speed reach ≈530 mA W−1, ≈1.21 × 1012 Jones and 30/14 µs, respectively, at zero bias under near‐infrared light illumination. Specifically, the responsivity is greatly enhanced by ≈2.65 times, as compared with a planar counterpart. In addition, the light detector can maintain its outstanding photoresponse properties upon 1000 cycles of bending test or at diverse bending radii of curvature, owing to its prominent mechanical flexibility and robust bending endurance. Finally, the capability of monitoring the heart rate of a person in a wideband wavelength spectrum and at various bending radii of curvature is presented. The above results imply the huge potential of the flexible light detector for use in some applications such as wearable health monitoring. [ABSTRACT FROM AUTHOR]

Broadband cyan‐emitting phosphors are crucial to close the cyan gap of phosphor‐converted white light‐emitting diodes (pc‐WLEDs) for full‐spectrum illumination. In this work, efficient cyan‐emitting Eu2+‐activated phosphor is achieved through structural modulation, which exhibits anti‐thermal quenching behavior. Redshift from blue (469 nm) to cyan (500 nm) emission and enhancement of emission is achieved by codoping Mg2+ and Ge4+ into Eu2+‐activated Na‐beta‐alumina phosphor. The introduction of Mg2+ ions dominates the redshift, while Ge4+ dominates the enhancement of emission. Furthermore, the introduction of Mg2+ and Ge4+ reduces the content of deep trap levels related to VNa defect, which decreases the degree of anti‐thermal quenching and results in better thermal stability. The prototype pc‐WLED by using the cyan‐emitting phosphor exhibits higher color‐rendering index and potential to close the cyan gap of pc‐WLEDs for full‐spectrum illumination. This work presents a paradigm for exploring phosphors with highly efficient and thermally stable emissions. [ABSTRACT FROM AUTHOR]

The features of hydrogen trapping under the irradiation of zirconium alloys E110 and E635 with an electron beam (400 eV, 0.8 mA/cm2) in various gaseous ambient containing oxygen and hydrogen (Ar + O2 + H2; Ar + H2O) are studied. The effect of surface temperature on the hydrogenation of zirconium alloys under electron irradiation is studied. It is shown that neither exposure nor electron irradiation in a gaseous ambient containing a mixture of H2 and O2 at 700 K for 20 h leads to a change in the hydrogen level in the E110 alloy, while hydrogen partially escapes from the E635 alloy during the experiment. The amount of hydrogen in zirconium alloys after exposure in a gaseous ambient containing H2O in a similar temperature–time regime also changes insignificantly; however, if the alloys are irradiated with electrons under these conditions, then they contain 1.5–2 times more hydrogen. When temperature of the samples is raised to 900 K, electron irradiation in the presence of water vapor, on the contrary, reduces the trapping of hydrogen in the E110 and E635 alloys, compared with exposure in the same gaseous ambient without irradiation. It is concluded that electron irradiation affects the balance of surface reactions of formation of hydroxyl groups from adsorbed water molecules and reverse reactions of formation of water molecules from surface hydroxyls. The direction of shifting the balance of these reactions depends on the surface temperature. [ABSTRACT FROM AUTHOR]