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Paper-based photodetectors are gaining attention in the field of optoelectronics due to their low cost, flexibility, and eco-friendliness. The paper-based devices have applications in areas like wearable devices, environmental monitoring, and point-of-care diagnostics, where these photodetectors exhibit significant potential. In the present work, we fabricated paper-based photodetectors functionalized by WS 2 /Ti 3 C 2 T x heterostructures. These materials were characterized by X-ray diffractometer, UV–visible spectroscopy, X-ray photoelectron spectroscopy, Raman spectroscopy, Energy dispersive spectroscopy, and Scanning electron microscopy. We fabricated a paper-based flexible device from this WS 2 /Ti 3 C 2 T x composite using a solvent-free, easily available, and cost-effective Hand-print method. We studied the I–V & I-t response of this device. The as-synthesized device shows excellent photodetection properties with a responsivity value of 3.06 mA/W, and 5.93 × 108 Jones specific detectivity. We further investigated the flexibility and durability of these devices. Finally, the current study supports a substantial advancement in the design of reliable, flexible, and large-area optoelectronic devices. • We fabricated paper-based photodetectors functionalized by WS 2 /Ti 3 C 2 T x heterostructures. • The responsivity of 3.06 mA/W, and specific detectivity of 5.93 × 108 Jones are achieved. • The flexibility and durability of this paper based devices were investigated. • WS 2 /Ti 3 C 2 T x heterostructures based photodetector shows broad spectral response. [ABSTRACT FROM AUTHOR]

• Zinc Selenide nanoflakes (ZnSe) - Zinc Oxide (ZnO) quantum dots (QDs) based vertical heterojunction was performed. • The device shows superior responsivity towards ultraviolet and visible. • The paper-based device shows excellent reliability and high stability for 500 bending cycles. ZnO-based photodetectors exhibit high responsivity and high photon absorption coefficients. However, they show absorption in a narrow range and a low photogenerated carrier lifetime, limiting their potential applications in optoelectronics. This work demonstrates a high-performance broadband photodetector using Zinc Selenide nanoflakes (ZnSe) - Zinc Oxide (ZnO) quantum dots (QDs) heterojunction. Using a simple hydrothermal method on a flexible paper substrate, this work overcomes the complexity of previously reported fabrication techniques that involve electrospinning, electron beam lithography, spin coating, etc. Detailed chemical and structural characterization reveal the formation of cubic phase of ZnSe nanoflakes-like structure showing broad absorption in the visible region. In contrast, ZnO QDs show a hexagonal structure and absorption in the ultraviolet region, improving the photodetector's detection range. The device shows superior responsivity (R ʎ) of 17.2 µA/W, and 30 µA/W, with specific detectivity (D*) of 4.74×107 Jones, and 9.39×107 Jones, for ultraviolet, and visible, respectively. Detailed studies based on energy band diagrams are performed to understand the charge transport mechanism. The device shows excellent reliability and high stability for 500 bending cycles, thus, presenting a low-cost, facile approach for developing high-performance photodetectors that find utility in wearables, healthcare, and security/defense applications. [Display omitted] [ABSTRACT FROM AUTHOR]

We present an investigation of inkjet printed strain gauges based on two-dimensional (2D) materials. The technology leverages water-based and biocompatible inks to fabricate strain measurement devices on flexible substrates such as paper. We demonstrate that the device performance and sensitivity are strongly dependent on the printing parameter (i.e., drop-spacing, number of printing passes, etc.). We show that values of the Gauge Factor up to 125 can be obtained, with large sensitivity (>20%) even when small strains (0.3%) are applied. Furthermore, we provide preliminary examples of heterostructure-based strain sensors, enabled by the inkjet printing technology. [ABSTRACT FROM AUTHOR]

It is a great challenge to synthesize efficient electrocatalysts for overall water splitting, especially non‐noble metal catalysts. Herein, one‐dimensional polycrystalline nanoneedles composed of CoO−Co9S8 nano heterostructures, in situ grown on carbon fiber paper are prepared for efficient overall water electrolysis. Due to strong electronic coupling, charge densities of Co2+/Co3+ in Co9S8 and Co2+ in CoO are favorably modified at the interface of CoO and Co9S8, resulting in optimized reaction intermediates absorption and greatly enhanced bifunctional HER/OER activities. CoO−Co9S8/CFP delivers a current density of 10 mA cm−2 in alkaline electrolyte at overpotentials of 184 mV and 270 mV for HER and OER, respectively. When used as electrocatalyst for overall water splitting, it needs a low cell potential of 1.66 V to realize water electrolysis at 10 mA cm−2. This work provides a new strategy to tune the electronic structures of transitional metal active sites via constructing nano heterostructures for efficient water electrolysis. [ABSTRACT FROM AUTHOR]

Although it suffers from a heavy dependence on the noble platinum catalyst, the electrochemical hydrogen evolution reaction (HER) is one of the most promising methods for the production of hydrogen. After numerous efforts, it is found that MoS2-based heterostructure may replace platinum as the electrochemical HER catalyst. In this work, the nanocrystalline NiSe2/MoS2 heterostructures were successfully prepared on the carbon fiber paper (CFP) substrate through electrochemical deposition and hydrothermal process. According to a series of electrochemical HER tests and a comparison with other MoS2-based heterostructure catalysts, the CFP/NiSe2/MoS2 catalyst with an overpotential η10 of 143 mV and a Tafel slope of 45 mV dec−1 exhibited an excellent electrochemical HER catalytic performance and durability. In addition, CFP/NiSe2/MoS2 catalyst was treated by plasma to further improve the catalytic performance of the catalyst. [ABSTRACT FROM AUTHOR]

The design and synthesis of 2D heterostructured materials for water splitting are normally based on van der Waals (vdW) nanosheets, but this approach is gradually approaching a performance ceiling in terms of activity and stability. Herein, a novel heterostructured system is explored based on 2D non‐vdW and conductive nanosheets. Notably, the interplanar growth of 2D non‐vdW Co2N nanosheets is realized between graphene layers in the current collector of carbon fiber papers (CPs), generating an interlocking structure within CPs. The exposed surface of Co2N nanosheets possesses a high surface energy that anchors highly active CoNC, forming 2D CoNC@Co2N heterostructures outside CPs. This integrated electrocatalytic system bridged by non‐vdW Co2N nanosheets presents a low overpotential of 1.52 V and an excellent stability of 280 h, which outperform most bifunctional and nonprecious‐metal‐based electrocatalysts in alkaline media, owing to the nature of 2D non‐vdW nanosheets and the formation of strong and conductive connections among CoNC, nanosheets, and CPs. [ABSTRACT FROM AUTHOR]

The critical challenges of Li-O2 batteries lie in sluggish oxygen redox kinetics and undesirable parasitic reactions during the oxygen reduction reaction and oxygen evolution reaction processes, inducing large overpotential and inferior cycle stability. Herein, an elaborately designed 3D hierarchical heterostructure comprising NiCO2S4@NiO core-shell arrays on conductive carbon paper is first reported as a freestanding cathode for Li-O2 batteries. The unique hierarchical array structures can build up multidimensional channels for oxygen diffusion and electrolyte impregnation. A built-in interfacial potential between NiCO2S4 and NiO can drastically enhance interfacial charge transfer kinetics. According to density functional theory calculations, intrinsic LiO2-affinity characteristics of NiCO2S4 and NiO play an importantly synergistic role in promoting the formation of large peasecodlike Li2O2, conducive to construct a low-impedance Li2O2/cathode contact interface. As expected, Li-O2 cells based on NiCO2S4@NiO electrode exhibit an improved overpotential of 0.88 V, a high discharge capacity of 10 050 mAh g-1 at 200 mA g-1, an excellent rate capability of 6150 mAh g-1 at 1.0 A g-1, and a long-term cycle stability under a restricted capacity of 1000 mAh g-1 at 200 mA g-1. Notably, the reported strategy about heterostructure accouplement may pave a new avenue for the effective electrocatalyst design for Li-O2 batteries. [ABSTRACT FROM AUTHOR]

Abstract: Single crystalline rare earth oxide heterostructures are flexible buffer systems to achieve the monolithic integration of Ge thin film structures on Si. The development of engineered oxide systems suitable for mass-production compatible CVD processes is hereby of special importance. In this paper, the interaction of Ge with PrO2(111)/Si(111) heterostructures is studied in detail to achieve this goal. MBE based in situ growth studies unveil the chemical reduction of the PrO2 buffer during the initial Ge deposition, the occurrence of a Volmer Weber growth mode of Ge on the resulting Pr2O3 heterostructure and the final formation of single crystalline, atomically smooth and c(2×8) reconstructed Ge(111) film structures. Comparative CVD Ge heteroepitaxy studies on MBE grown PrO2(111)/Si(111) and Pr2O3(111)/Si(111) buffer systems indicate that the highly reactive lattice oxygen of PrO2 plays an active role to avoid during initial exposure to the reducing ambient of the GeH4 precursor chemistry the decomposition of the oxide buffer system. [Copyright &y& Elsevier]

TThe object of research is the donor-acceptor compound, organic and hybrid heterostructures based on it. The paper is focused on a comprehensive approach to solving the problem of the efficiency of light-emitting devices, finding new technological and design solutions for the use of organic compounds as multifunctional materials for various types of light-emitting devices. The paper presents the multifunctional application of a planar 2D molecule as an emission layer for typical and inverted types of light-emitting heterostructures, as well as a matrix for a host-guest system using inorganic quantum dots. The developed light-emitting structures are characterized by external quantum efficiency typical for fluorescent devices, but good stability over the entire length of the consumption voltage. QLED brightness is 1600 cd·m-2 and EQE 1.4 %, which are good parameters for use in display technology. Organic LEDs based on planar molecules are promising candidates for use in modern lighting systems. A separate advantage of these light-emitting structures is the multifunctionality of using one compound for different types of light-emitting structures, including inverted heterostructures. Special attention is paid to the technological and design implementation of invert structures, since their geometry allows direct connection to the back board of the n-channel transistor on the substrate. In addition, organic LEDs have low energy consumption and are environmentally friendly due to the absence of toxic substances in their architecture, which creates the prerequisites for saving energy resources and reducing the industrial burden on the environment. [ABSTRACT FROM AUTHOR]

Abstract: Heterostructured metal oxide core–shell architectures have attracted considerable attention owing to their superior electrochemical performance in supercapacitors compared to a single structure. Here, we report a simple and effective synthesis of hierarchical MnCo2O4 nanowire@MnO2 sheet core–shell nanostructures anchored on graphite paper for use in supercapacitors. The proposed electrode exhibits a specific capacitance of 2262 F g−1 at 1 A g−1. In addition, good rate capability and excellent cycling performance are observed. An asymmetric supercapacitor with operating potential at 1.6 V is demonstrated using MnCo2O4@MnO2 as cathode and graphene/nickel foam (NF) as anode. The MnCo2O4@MnO2//graphene/NF asymmetric device shows a high energy density of 85.7 Wh kg−1 at a power density of 800 W kg−1 while maintaining a high energy density of 34.7 Wh kg−1 at 24 kW kg−1. Moreover, the device demonstrates a long‐term cycling stability of 81.6 % retention of its initial specific capacitance. [ABSTRACT FROM AUTHOR]

Spin pumping and spin-orbit torques play important roles in advancing spintronic device technologies. Our curated special issue focuses on these phenomena in magnetic heterostructures, which are critical for various applications. The high-quality papers1,2,3,4,5,6,7 delve into spin pumping and spin-orbit torques in diverse heterostructures, addressing topics such as insulating/metallic interfaces tailoring spin-to-charge conversion, the influence of HfOx capping layers on perpendicular magnetic anisotropy, anisotropy-controlled spin current generation, sputter pressure-dependent spin Hall angle, the effect of oxygen ion irradiation on spin-orbit torques, and a review paper of emerging two-dimensional/ferromagnetic interfaces. This Editorial discusses the reported articles and the future perspective of these topics. With this special issue, we anticipate significant contributions to both academic research and industrial developments in this direction. [ABSTRACT FROM AUTHOR]

In the pursuit of developing high-performance low-dimensional spintronic devices, two-dimensional van der Waals heterostructures comprising non-magnetic nitride and ferromagnetic materials have emerged as a crucial area of investigation. This paper proposes a novel structure that employs hexagonal two-dimensional semiconductor GaN flanked by two half-metallic two-dimensional CrN layers. The stability of the proposed structure is verified via first-principles calculations, which indicate good thermodynamic and magnetic stability. The transport characteristics of electrons in the structure are analyzed through the Band structures and density of states. Specifically, the study examines the spin polarizability of parallel and anti-parallel magnetic configurations of the CrN/GaN/CrN vdW heterostructure, and the results demonstrate a significant spin valve effect. Overall, the study establishes the potential of the CrN/GaN/CrN vdW heterostructure as a candidate for the development of innovative spintronic devices. [ABSTRACT FROM AUTHOR]

This paper reports that the in situ growth magnetic field (Hg) during magnetic-phase CoFeB deposition impacts the electric-field control of magnetic anisotropy in Co40Fe40B20/(011)-Pb(Mg1/3Nb2/3)0.7Ti0.3O3 [CoFeB/(011)-PMN-PT] composite multiferroic heterostructures at room temperature. In the Hg1 mode (in situ Hg along the [ 01 1 ¯ ] direction of the ferroelectric PMN-PT substrate), the electric-field-controlled modulation ratios of the magnetic coercivity HC and saturation magnetic field HS are approximately −47% and +156%, respectively. However, in the Hg2 mode (in situ Hg along the [100] direction of the ferroelectric PMN-PT substrate) of the CoFeB/(011)-PMN-PT multiferroic heterostructure, the electric-field-controlled modulation ratios of the magnetic coercivity HC and saturation magnetic field HS can reach as high as +162% and +393%, respectively. Moreover, the electric-field-controlled magnetic coercive field HC exhibits a butterfly shape when plotted versus the applied electric fields in both modes, which matches the in-plane butterfly strain loop of the ferroelectric PMN-PT substrate. However, the electric-field-controlled saturation magnetic field HS presents a square loop, which is very consistent with the ferroelectric loop of the PMN-PT substrate. This result may be ascribed to the distinct pathway of the ferroelastic domain switching in the (011)-oriented PMN-PT substrate. This study provides a new idea for the design of spintronic devices based on multiferroic heterostructures. [ABSTRACT FROM AUTHOR]

This review paper focuses on present issues concerning the use of polyaniline–TiO2 heterostructures as potentially efficient photocatalysts. Conducting polymers such as polyaniline (PANI) are used in the preparation of heterojunction systems with metal oxides like titania to overcome their inherent limitations, e.g., their sole absorption of UV light and overly fast recombination of charge carriers. This review discusses preparation methods, the properties of resultant products and mechanistic aspects. An important part of this paper is its presentation of the major challenges and future perspectives of such photocatalytic materials. [ABSTRACT FROM AUTHOR]

Purpose: In this paper, we consider p–n-junctions, manufactured by diffusion or ion implantation in a heterostructures. We analyzed influence of existing in heterostructure mismatch induced stresses on the current-voltage characteristics of the p–n-junctions. We also introduce an analytical approach for analysis of mass and heat transfer in heterostructures with account changes of their parameters on time, as well as their nonlinearity and mismatch induced stresses. In this paper we introduce an analytical approach for prognosis of the considered processes. Design/methodology/approach: In this paper, we consider p–n-junctions, manufactured by diffusion or ion implantation in a heterostructures. We analyzed influence of existing in heterostructure missmatch induced stresses on the current-voltage characteristics of the p–n-junctions. We also introduce an analytical approach for analysis of mass and heat transfer in heterostructures with account changes of their parameters on time, as well as their nonlinearity and missmatch induced stresses. In this paper we introduce an analytical approach for prognosis of the considered processes. Findings: In this paper, we consider p–n-junctions, manufactured by diffusion or ion implantation in a heterostructures. We analyzed influence of existing in heterostructure missmatch induced stresses on the current-voltage characteristics of the p–n-junctions. We also introduce an analytical approach for analysis of mass and heat transfer in heterostructures with account changes of their parameters on time, as well as their nonlinearity and missmatch induced stresses. In this paper we introduce an analytical approach for prognosis of the considered processes. Originality/value: This paper is original. [ABSTRACT FROM AUTHOR]

Aqueous zinc ion batteries (AZIBs) have received a lot of attention in electrochemical energy storage systems for their low cost, environmental compatibility, and good safety. However, cathode materials still face poor material stability and conductivity, which cause poor reversibility and poor rate performance in AZIBs. Herein, a heterogeneous structure combined with cation pre-intercalation strategies was used to prepare a novel CaV6O16·3H2O@Ni0.24V2O5·nH2O material (CaNiVO) for high-performance Zn storage. Excellent energy storage performance was achieved via the wide interlayer conductive network originating from the interlayer-embedded metal ions and heterointerfaces of the two-phase CaNiVO. Furthermore, this unique structure further showed excellent structural stability and led to fast electron/ion transport dynamics. Benefiting from the heterogeneous structure and cation pre-intercalation strategies, the CaNiVO electrodes showed an impressive specific capacity of 334.7 mAh g−1 at 0.1 A g−1 and a rate performance of 110.3 mAh g−1 at 2 A g−1. Therefore, this paper provides a feasible strategy for designing and optimizing cathode materials with superior Zn ion storage performance. [ABSTRACT FROM AUTHOR]

Highly sensitive infrared photodetectors are needed in numerous sensing and imaging applications. In this paper, we report on extended short-wave infrared (e-SWIR) avalanche photodiodes (APDs) capable of operating at room temperature (RT). To extend the detection wavelength, the e-SWIR APD utilizes a higher indium (In) composition, specifically In0.3Ga0.7As0.25Sb0.75/GaSb heterostructures. The detection cut-off wavelength is successfully extended to 2.6 µm at RT, as verified by the Fourier Transform Infrared Spectrometer (FTIR) detection spectrum measurement at RT. The In0.3Ga0.7As0.25Sb0.75/GaSb heterostructures are lattice-matched to GaSb substrates, ensuring high material quality. The noise current at RT is analyzed and found to be the shot noise-limited at RT. The e-SWIR APD achieves a high multiplication gain of M ~ 190 at a low bias of V b i a s = −   2.5   V under illumination of a distributed feedback laser (DFB) with an emission wavelength of 2.3 µm. A high photoresponsivity of R > 140   A / W is also achieved at the low bias of V b i a s = − 2.5   V . This type of highly sensitive e-SWIR APD, with a high internal gain capable of RT operation, provides enabling technology for e-SWIR sensing and imaging while significantly reducing size, weight, and power consumption (SWaP). [ABSTRACT FROM AUTHOR]

The work function is a critical parameter for device design and understanding of materials properties, but contemporary experimental literature on tailored work functions is rather scarce. This paper presents a promising new approach to work function design that uses pulsed laser deposition (PLD) growth with unit cell precision. It is shown that a monolayer buried within a material can influence the work function as a function of the layer depth. This method can preserve properties of the original material's surface, and furthermore, a sensitive material can be used as the monolayer, both of which are beneficial for device design. Proof of concept is demonstrated by inserting a nominal monolayer of barium oxide (BaO) into strontium titanate (SrTiO3) (001) at different depths, revealing a previously unknown work function trend. Density functional theory (DFT) calculations, surface characterization, and scanning transmission electron microscopy (STEM) studies verify the quality of the heterostructures and help to understand how charge transfer, slight barium diffusion, and termination effects account for the observed work function trends. This work function tunability is a promising approach for future devices that require a tailored work function, which can easily be extended to a wider variety of materials. [ABSTRACT FROM AUTHOR]

The need for photosensors and gas sensors arises from their pivotal roles in various technological applications, ensuring enhanced efficiency, safety, and functionality in diverse fields. In this paper, interlinked PbS/Sb2O5 thin film has been synthesized by a magnetron sputtering method. We control the temperature to form the nanocomposite by using their different nucleation temperature during the sulfonation process. A nanostructured PbS/Sb2O5 with cross-linked morphology was synthesized by using this fast and efficient method. This method has also been used to grow a uniform thin film of nanocomposite. The photo-sensing and gas-sensing properties related to the PbS/Sb2O5 compared with those of other nanomaterials have also been investigated. The experimental and theoretical calculations reveal that the PbS/Sb2O5 exhibits extraordinarily superior photo-sensing and gas-sensing properties in terms of providing a pathway for electron transport to the electrode. The attractive highly sensitive photo and gas sensing properties of PbS/Sb2O5 make them applicable for many different kinds of applications. The responsivity and detectivity of PbS/Sb2O5 are 0.28 S/mWcm−2 and 1.68 × 1011 Jones respectively. The sensor response towards NO2 gas was found to be 0.98 at 10 ppb with an limit of detection (LOD) of 0.083 ppb. The PbS/Sb2O5 exhibits high selectivity towards the NO2 gas. Density functional theory (DFT) and time-dependent density functional theory (TD-DFT) were used to analyze the geometries, electronic structure, and electronic absorption spectra of a light sensor fabricated by PbS/Sb2O5. The results are very analogous to the experimental results. Both photosensors and gas sensors are indispensable tools that contribute significantly to the evolution of technology and the improvement of various aspects of modern life. [ABSTRACT FROM AUTHOR]

Interest in fullerene-based polymer structures has renewed due to the development of synthesis technologies using thin C60 polymers. Fullerene networks are good semiconductors. In this paper, heterostructure complexes composed of C60 polymer networks on atomically thin dielectric substrates are modeled. Small tensile and compressive deformations make it possible to ensure appropriate placement of monolayer boron nitride with fullerene networks. The choice of a piezoelectric boron nitride substrate was dictated by interest in their applicability in mechanoelectric, photoelectronic, and electro-optical devices with the ability to control their properties. The results we obtained show that C60 polymer/h-BN heterostructures are stable compounds. The van der Waals interaction that arises between them affects their electronic and optical properties. [ABSTRACT FROM AUTHOR]

In this paper, an innovative vertical bi-channel tunnel field effect transistor is presented that exploits line tunneling mechanism to achieve improved electrical performance. In this device, the source contains germanium, while the channel and drain regions consist of GaAs., which results in a type-II heterostructure with low resistance tunneling barrier. The source region is situated in a vertical position, enclosed by two sidewall channels that encompass a broad area of tunneling. Our proposed design effectively blocks the electric field that is originated from the drain at the tunneling junction, thereby conferring high immunity to drain induced barrier thinning effect. The device that has been suggested offers a significantly greater on-state current, a factor of 144, when compared to the traditional TFET and provides a subthreshold swing of 3mV/dec and an on/off current ratio of 9.76x1010. According to statistical analysis, the design parameters of metal gate workfunction value and source doping concentration are crucial and have the potential to impact device performance. Therefore, selecting the appropriate combination of these parameters is essential. The proposed device serves as a foundation for the development of computing systems that are low in power and high in speed. [ABSTRACT FROM AUTHOR]

The stacking orders that may be generated by mirroring a layer of Cr X 3 (X = I, Br, Cl) through its Cr atomic layer in heterostructures are easy to be ignored so that the influence of these stacking orders has not yet been well explored. In this paper, we have constructed all eight stable highly symmetric stacking orders that maintain translational symmetry in a Cr I 3 / α - In 2 S e 3 heterostructure and systematically studied the dependence of the structure, magnetism, electronic structure on stacking orders, and ferroelectric polarization directions by using the first principles method, especially that the system energy and magnetism have certain differences between normal and mirror stacking orders. The regulation of system energy and interlayer distance, magnetism, and band structure can be, respectively, explained by the different stacking relationships of atomic layers in different stacking orders, the different influences of different deformations of a Cr I 3 atomic structure on a magnetic exchange interaction in different stacking orders, and the different band alignments corresponding to different vacuum energy levels at different interfaces of α - In 2 S e 3. Our work will have a certain reference value for understanding the material properties and practical applications of such ferromagnetic/ferroelectric heterostructures. [ABSTRACT FROM AUTHOR]

Two-dimensional (2D) valleytronic materials are both fundamentally intriguing and practically appealing to explore novel physics and design next-generation devices. However, traditional control means such as optic pumping or magnetic field cannot meet the demands of modern electron devices for miniaturization, low-dissipation, and non-volatility. Thus, it is attractive to combine the ferroelectric property with valley property in a single compound. In this paper, the recent progress of ferroelectric-valley coupling is reviewed. First, we briefly recall the development of valleytronics in the past several years. Then, various structures demonstrating ferroelectric-valley coupling, including heterostructures and intrinsic materials, are introduced. Subsequently, we describe ferroelectric-valley coupling in sliding and adsorption system and the unconventional ferroelectricity in the moiré system. Finally, we discuss the research status and outlook. We hope that this perspective will be helpful to bridge the gap between valleytronics and ferroelectrics in 2D materials and inspire further exciting findings. [ABSTRACT FROM AUTHOR]

The fabrication of artificial heterostructures is mainly based on substitution systems. We present simple ways to construct double-sided versions of the Fibonacci, Prouhet-Thue-Morse, paperfolding, period doubling and Golay-Rudin-Shapiro sequences. We also construct a generic instance of the two-dimensional Prouhet-Thue-Morse structure and explore its symbolic complexity. The complexity turns out to be polynomial and hence, the entropy goes to zero. [ABSTRACT FROM AUTHOR]

The reliability of oxide‐semiconductor (OS) thin‐film transistors (TFTs) is significantly influenced by the gate insulator (GI). During electrical bias stress, the defect sites near the semiconductor/GI interface and/or within the GI may trap electrons, which makes the threshold voltage (Vth) shift toward positive values. On the other hand, carbon (C) or hydrogen (H) atoms may diffuse from the GI into the active layer, and act as shallow donors, which induce negative Vth shifts (ΔVth). In this paper, an in situ atomic layer deposition (ALD)‐based GI heterostructure is introduced, which consists of a stack of two complementary materials, namely Al2O3 and SiO2. Here, a competition occurs between electron trapping in Al2O3 (positive ΔVth) and carrier generation from H atoms in SiO2 (negative ΔVth) which allows the achievement of nearly zero ΔVth under positive bias temperature stress (PBTS). This strategy is successfully applied to a high‐mobility (>50 cm2 Vs−1) ALD‐based indium‐gallium‐zinc oxide (IGZO) device, resulting in a net ∆Vth of −0.02 V under PBTS and drain current variation (∆ID) of +0.49% under constant current stress (CCS). The application of an in situ ALD process thus offers valuable insights to resolve the mobility versus reliability trade‐off in high‐performance oxide TFTs. [ABSTRACT FROM AUTHOR]

To solve the shuttling effect and transformations of LiPSs in lithium–sulfur batteries, heterostructures have been designed to immobilize LiPSs and boost their reversible conversions. In this paper, we have constructed AlN/InN heterojunctions with AlN with a wide band gap and InN with a narrow band gap. The heterojunctions show metallic properties, which are primarily composed of 2s, 2p N atoms and 5s, 5p In atoms. InN has relatively higher adsorptivity for LiPSs than AlN. Reaction profiles show that on the surface of AlN, there is a lower rate-limiting step than on that of InN, from S8 to Li2S6, and a higher rate-limiting step from Li2S4 to Li2S2, which is more favorable for InN during the reduction from Li2S4 to Li2S2. The heterojunction can realize the synergistic reaction of trapping–diffusion–conversion for LiPSs, in which AlN traps large Li2S8 and Li2S6, the heterojunction causes the diffusion of Li2S4, and InN completes the conversion of Li2S4 to Li2S. [ABSTRACT FROM AUTHOR]

During the past decade, Gallium Oxide (Ga2O3) has attracted intensive research interest as an ultra-wide-bandgap (UWBG) semiconductor due to its unique characteristics, such as a large bandgap of 4.5–4.9 eV, a high critical electric field of ~8 MV/cm, and a high Baliga's figure of merit (BFOM). Unipolar β-Ga2O3 devices such as Schottky barrier diodes (SBDs) and field-effect transistors (FETs) have been demonstrated. Recently, there has been growing attention toward developing β-Ga2O3-based heterostructures and heterojunctions, which is mainly driven by the lack of p-type doping and the exploration of multidimensional device architectures to enhance power electronics' performance. This paper will review the most recent advances in β-Ga2O3 heterostructures and heterojunctions for power electronics, including NiOx/β-Ga2O3, β-(AlxGa1−x)2O3/β-Ga2O3, and β-Ga2O3 heterojunctions/heterostructures with other wide- and ultra-wide-bandgap materials and the integration of two-dimensional (2D) materials with β-Ga2O3. Discussions of the deposition, fabrication, and operating principles of these heterostructures and heterojunctions and the associated device performance will be provided. This comprehensive review will serve as a critical reference for researchers engaged in materials science, wide- and ultra-wide-bandgap semiconductors, and power electronics and benefits the future study and development of β-Ga2O3-based heterostructures and heterojunctions and associated power electronics. [ABSTRACT FROM AUTHOR]

High-mobility spin-polarized two-dimensional electron gas (2DEG) at the interfaces of complex oxide heterostructures provide great potential for spintronic device applications. Unfortunately, the interfacial ferromagnetism and its associated spin polarization of mobile electrons and negative magnetoresistance (MR) are too weak. As of now, obtaining enhanced interfacial ferromagnetism and MR and strong spin-polarized 2DEG is still a great challenge. In this paper, we report on the realization of strong spin-polarized 2DEG at the interface of EuTiO3/SrTiO3 (110) heterostructures, which were prepared by directly depositing 39-nm EuTiO3 films onto as-received SrTiO3 (110) substrates. Hall and Kondo effects, low-field MR, Shubnikov–de Haas (SdH) oscillation, and magnetic hysteresis loop measurements demonstrate that high mobility electrons (1.4 × 104 cm2 V−1 s−1) accumulate at the interface of the heterostructures, which are not only highly conducting and show SdH oscillations with a non-zero Berry phase but also show a large out-of-plane and in-plane butterfly-like negative low-field MR whose magnitude is unprecedentedly large (46%–59% at 500 Oe and 1.8 K), approximately one to two orders higher than those of previously reported spin-polarized 2DEG systems. The strong spin polarization of the interfacial 2DEG is attributed to the presence of interfacial Eu2+ 4f (3.6–4 μB/f.u.) and Ti3+ 3d moments. Our results may provide guidance for exploring strong spin-polarized 2DEG at the interface of rare-earth titanate–strontium titanate heterostructures. [ABSTRACT FROM AUTHOR]

This paper proposes a new type of substrate for manufacturing LEDs based on AlInGaN heterostructures. Instead of depositing SiC layers on the surface of Si using the conventional method, a new method involving the coordinated substitution of atoms (MCSA) to form the SiC layer is proposed. This new approach enables the growth of epitaxial GaN layers with low defect content and facilitates transfer to any surface. The paper details the technology of manufacturing LEDs on SiC/Si substrates obtained by the MCSA and elaborates on the benefits of using these substrates in LED production. Additionally, the advantages of the growth interface between SiC and Si materials are discussed. Moreover, it is found that thinner SiC layers (<200 nm) contribute to the scattering of the LED's own radiation in the heterostructure waveguide, which decreases its absorption by silicon. For flip-chip LEDs with the substrate removed, substrates with thicker SiC layers (~400 nm) and a growth porous layer of several microns at the SiC-Si interface is utilized to simplify Si substrate removal and enhance the manufacturing process's cost-effectiveness. [ABSTRACT FROM AUTHOR]

Transparent oxide has attracted increasing interest as a new TFT material, but is limited by relatively low electronic performance and poor mechanical flexibility. Here we will discuss the use of oxide /carbon nanotube composite and oxide/graphene vertical heterostructures to achieve TFTs with greatly improved electronic characteristics and unprecedented mechanical flexibility. [ABSTRACT FROM AUTHOR]

Molybdenum (Mo) is one of the most important constituent elements in natural nitrogenase and theoretical calculation results show that Mo-based materials can be used as potential NRR electrocatalysts. The design of advanced catalysts with a special structure is very essential for promoting the development of electrocatalytic N2 into NH3. In this paper, Fe-doped MoO2/C heterostructured nanoparticles with rich oxygen vacancies (Vo) are designed and they exhibit highly efficient catalytic activity for artificial N2 fixation in neutral electrolytes under ambient conditions. The influence of the atomic ratio of the Fe source to the Mo source and the NaBH4 ethanol solution treatment on the structure and electrocatalytic performance are systematically investigated. The Vo-Fe–MoO2/C (1 : 50) catalyst with rich oxygen vacancies shows a satisfactory electrocatalytic N2 reduction reaction (e-NRR) activity in 0.1 M Na2SO4 with a high ammonia yield rate of 15.87 ± 0.3 μg h−1 mg−1 at −0.5 V versus the reversible hydrogen electrode (vs. the RHE) and a FE of 13.4% at −0.3 V (vs. the RHE). According to the results of DFT calculations, the active center of the electro-catalytic nitrogen reduction reaction is the molybdenum atom between the iron atom and the O vacancy. Oxygen vacancies can not only reduce the energy barrier of the RDS but also facilitate the desorption of ammonia and the first step hydrogenation of nitrogen. The doping of Fe will change the electronic state of the Mo atom in MoO2. [ABSTRACT FROM AUTHOR]

We have obtained novel photosensitive materials containing a semiconductor photocatalyst and a dye sensitizer. We have studied the activity of the latter in the reaction of photoreduction of methylene blue, and we consider possible mechanisms for the photocatalytic effect [ABSTRACT FROM AUTHOR]

Two-dimensional materials have been extensively investigated for fabricating high-performance visible optoelectronic devices. Considering the significance of mid-infrared band, narrow-band two-dimensional semiconductor materials have become the key point. In this work, we bring out two kinds of monolayer lateral heterostructures (LHSs) based on arsenic (As)/antimony (Sb) to realize the narrow band structure. The bandgap of LHS with an armchair interface is calculated to be 1.1 eV with an indirect band through the first principle, and the bandgap of LHS with a zigzag interface is 0.57 eV with a direct band. Their bandgaps are all shrunk by applying tensile or compressive strains. Furthermore, indirect-to-direct transitions appear in the armchair LHS when tensile strains are applied. Partial density-of-states and charge density distributions indicate that electron transmission from Sb atoms to As atoms may be the main factor for the reduction of the bandgap. In addition, the tensile strain extends the optical absorption to the infrared region. The As/Sb lateral heterostructures proposed in this paper are of great significance for infrared optoelectronic devices. [ABSTRACT FROM AUTHOR]

This paper presents the measurement of strain-mediated multiferroic control of spontaneous exchange bias (SEB) in magnetostrictive nickel/nickel oxide (Ni/NiO) bilayers on ferroelectric lead magnesium niobate-lead titanate (PMN-PT). Electric field control of a positive to negative exchange bias shift was measured, with an overall shift of 40.5 Oe, corresponding to a 325% change. Observed changes in coercivity are also reported and provide insight into the role of competing anisotropies in these structures. The findings in this paper provide evidence that magnetoelastic anisotropy can be utilized to control spontaneous exchange bias (SEB). This control of SEB is accomplished by modifying a bulk anisotropy (magnetoelasticity) that adjusts the mobility of interfacial anti-ferromagnetic spins and, therefore, the magnitude of the exchange bias. The demonstrated magnetoelastic control of exchange bias provides a useful tool in the creation of future magnetoelectric devices. [ABSTRACT FROM AUTHOR]

In this paper, we formed two graphene/C2P4 van der Waals (vdW) heterostructures (HSs) by stacking the graphene and the C2P4 monolayer which have been predicted by us. First, we investigated the stability of C2P4 monolayer, and calculated the binding energies and flat average differential charge density of two vdW-HSs. Second, we found that two graphene/C2P4 vdW-HSs are all direct semiconductors with bandgap as 0.051/0.064 eV and 0.536/0.697 eV under GGA-PBE/HSE06 functional, respectively, which provides a way to unfold the zero bandgap of graphene or let an indirect monolayer to be a relevant direct semiconductor. Additionally, two graphene/C2P4 vdW-HSs possess high absorption coefficients (16%∼18%) for the visible light and higher absorption coefficients (22%) for the near ultraviolet light, respectively. These admirable properties make two vdW-HSs as novel and potential two-dimensional materials applied on optoelectronic, electronic and photovoltaics devices. [ABSTRACT FROM AUTHOR]

The capacity to manipulate magnetization in 2D dilute magnetic semiconductors (2D‐DMSs) using light, specifically in magnetically doped transition metal dichalcogenide (TMD) monolayers (M‐doped TX2, where M = V, Fe, and Cr; T = W, Mo; X = S, Se, and Te), may lead to innovative applications in spintronics, spin‐caloritronics, valleytronics, and quantum computation. This Perspective paper explores the mediation of magnetization by light under ambient conditions in 2D‐TMD DMSs and heterostructures. By combining magneto‐LC resonance (MLCR) experiments with density functional theory (DFT) calculations, we show that the magnetization can be enhanced using light in V‐doped TMD monolayers (e.g., V‐WS2, V‐WSe2). This phenomenon is attributed to excess holes in the conduction and valence bands, and carriers trapped in magnetic doping states, mediating the magnetization of the semiconducting layer. In 2D‐TMD heterostructures (VSe2/WS2, VSe2/MoS2), the significance of proximity, charge‐transfer, and confinement effects in amplifying light‐mediated magnetism is demonstrated. We attributed this to photon absorption at the TMD layer that generates electron–hole pairs mediating the magnetization of the heterostructure. These findings will encourage further research in the field of 2D magnetism and establish a novel design of 2D‐TMDs and heterostructures with optically tunable magnetic functionalities, paving the way for next‐generation magneto‐optic nanodevices. [ABSTRACT FROM AUTHOR]

Most 2D materials are unstable under ambient conditions. Assembly of van der Waals heterostructures in the inert atmosphere of the glove box with ex situ lithography partially solves the problem of device fabrication out of unstable materials. In our paper, we demonstrate an approach to the next-generation inert-atmosphere (nitrogen, <20 ppm oxygen content) fabrication setup, including optical contact mask lithography with a 2 μ m resolution, metal evaporation, lift-off and placement of the sample to the cryostat for electric measurements in the same inert atmosphere environment. We consider basic construction principles, budget considerations, and showcase the fabrication and subsequent degradation of black-phosphorous-based structures within weeks. The proposed solutions are surprisingly compact and inexpensive, making them feasible for implementation in numerous 2D materials laboratories. [ABSTRACT FROM AUTHOR]

In this paper we develop a stochastic simulation algorithm for electron transport in a DA-pHEMT heterostructure. Mathematical formulation of the problem of electron gas transport in the heterostructure in the form of a coupled system of Poisson, Schrödinger and kinetic Boltzmann equations is given. A Monte Carlo model of electron transport in DA-pHEMT heterostructures which accounts for multivalley parabolic band structure, as well as relevant formulas for calculating electron scattering rates and scattering phase functions on polar optical, intervalley phonons and on impurities are developed. The results of a computational experiment involving the solution of the system of Poisson–Schrödinger–Boltzmann equations for the AlGaAs/GaAs/InGaAs/GaAs/AlGaAs heterostructure are presented. The distribution of electrons by energy subband in the main and satellite valleys and the field dependences of the electron drift velocity in each valley are calculated. It was discovered that there is no spatial transfer of electrons into wide-gap AlGaAs layers due to high barriers created by modulated-doped impurities. A comparative analysis of the electron drift velocities in the studied DA-pHEMT heterostructures and in the unstrained layer of the InGaAs is given. [ABSTRACT FROM AUTHOR]

The p-n junction is the fundamental building block for electronics and photonics applications. In a conventional p-n junction, the performance parameters cannot be tuned due to the fixed doping level after ion implantation. In this paper, reconfigurable p-n or n-p junctions were built based on the ambipolar black phosphorus (BP) and other 2-D materials, namely, graphene and hexagonal boron nitride (h-BN). High-quality graphene/h-BN/BP/h-BN sandwich device was created by the dry transfer method in an inert environment. Graphene serves as the local back gate, which can tune BP partially into either n-type or p-type material. The rest of the BP channel can be controlled by the back gate. The BP encapsulated device can enable the high performance of the ideality factor down to 1.08 (p-n junction) and 1.18 (n-p junction). The device developed in this paper has a more balanced ideality factor than previously reported reconfigurable WSe2 and BP devices. By tuning the back gate and graphene gate, the BP device can be tuned into four operational quadrants, namely, n-n, n-p, p-n, and p-p junctions. Moreover, the hole mobility of BP is up to 404 cm2/ $\text {V}\cdot \text {s}$ at room temperature. Our work shows that the BP heterostructure is very promising for high-speed reconfigurable logic functions and circuits. [ABSTRACT FROM AUTHOR]

Esaki diodes based on interband tunneling have the characteristics of negative differential resistance (NDR) and ultrafast transient time, which lead to broad applications including oscillators, multivalue memories, and terahertz detectors. In this paper, we present the first demonstration of Esaki diodes based on 2-D/3-D heterojunctions—more specifically, chemical vapor deposition MoS2 on degenerately doped silicon. As compared to traditional 3-D heterostructures, these 2-D/3-D heterostructures have the following advantages: dislocation-free 2-D crystals even when the lattices are mismatched, dangling bond-free surface, and capability for large-scale synthesis at low cost. In this paper, monolayer, bilayer, and trilayer MoS2 are synthesized directly on degenerated Si substrate, forming the ultraclean heterostructures without surface contamination from tape and resist. Based on these pristine heterostructures, we are able to observe prominent NDR effect at room temperature. This NDR effect is attributed to the degenerately p-type doping in silicon and the natural n-type doping in MoS2. We also found that the peak voltage corresponding to the local maximum tunneling current depends on the MoS2 thickness. While MoS2 is changing from the monolayer (0.7 nm) to bulk (9.5 nm), the peak voltage increases from 0.8 to 1.6 V. This phenomenon can be explained by the energy-level differences between the monolayer and bulk MoS2. This paper provides the experimental groundwork for the synthesis of transition metal dichalcogenides on degenerately doped Si substrates and opens up new and exciting opportunities for electronic applications of 2-D/3-D heterostructures. [ABSTRACT FROM AUTHOR]

In this paper, we report on the influence of surface (donor and acceptor) states and interface charges on the formation of 2-D electron gas (2DEG) in MgZnO/ZnO heterostructure grown by sputtering. Donor and acceptor states alone cannot yield an order of magnitude higher value of 2DEG as observed by sputtering growth as compared to epitaxial techniques. While surface donor states are reported to govern the formation of 2DEG in epitaxially grown heterostructures, our simulations suggest a non-negligible contribution of surface acceptor states in the 2DEG density. In addition, the existence of interface charges due to high defect density along with appropriate values of donor and acceptor states is essential to accurately predict an order of magnitude higher 2DEG density grown by sputtering. This paper analyzes the distinct roles of donor and acceptor states along with interface charges in 2DEG formation and achieved values. [ABSTRACT FROM AUTHOR]

In SiN/AlGaN/GaN heterostructures, the evaluation of interface charges at the SiN/AlGaN and AlGaN/GaN interfaces is crucial since they both rule the formation of the two-dimensional electron gas (2DEG) at the AlGaN/GaN interface. In this paper, we conducted a thorough analysis of the gate-to-channel capacitance CGC(VG) and of the drain current ID(VG) over a gate voltage VG range enabling the depletion of the 2DEG and the formation of the electron channel at the SiN/AlGaN interface. This work includes the establishment of analytical equations for V T H 1 (formation of the 2DEG) and V T H 2 (formation of the electron channel at the SiN/AlGaN interface) as a function of interface charges and of the p-doping below the 2DEG. The inclusion of the p-doped layer below the 2DEG and the use we made of V T H 2 have not been reported in previous studies. Our analysis allows a reliable estimate of the interface charges at the AlxGa1−xN/GaN and SiN/AlxGa1−xN interfaces for various Al concentrations x as well as to demonstrate that the polarization charge at the SiN/AlxGa1−xN interface is compensated, which confirms previous findings. Moreover, this compensation is found to be induced by the AlGaN layer rather than the SiN layer. [ABSTRACT FROM AUTHOR]

In this paper, detailed models of GaTe/XSe heterojunctions are constructed and geometrically optimised. The GaTe/InSe(X = Zn, In) heterojunction is calculated to be a Type-II direct bandgap semiconductor with a forbidden bandwidth of 1.26 eV based on the DFT study, while the GaTe/ZnSe heterojunction behaves as a Type-II indirect bandgap semiconductor with a forbidden bandwidth of 0.899 eV. The forbidden bandwidth reaches its maximum value at 2% of tensile strain. When the compressive strain reaches −8%, the forbidden bandwidth is 0 and the heterojunction is converted from a semiconductor to a conductor. The analysis of the absorption spectra of GaTe/InSe and GaTe/ZnSe heterojunctions shows that both heterojunctions increase the absorption in the visible region as well as broaden the absorption range of the spectrum. Therefore, GaTe/InSe heterojunctions are useful in the field of optoelectronic devices. • The band gap width of the GaTe/InSe heterojunction is calculated to be 1.254 eV, and this heterojunction is a direct band gap semiconductor. The band gap width of the GaTe/ZnSe heterojunction is 0.899 eV, and this material is an indirect band gap semiconductor. • GaTe/ZnSe and GaTe/InSe heterojunctions have good optoelectronic properties with smaller bandgap widths and a wider range of light absorption. [ABSTRACT FROM AUTHOR]