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YxAl1 − xN in its wurtzite phase has been identified as a prospective wide bandgap semiconductor and a promising competitor of ScxAl1 − xN in application devices. Notwithstanding theoretical predictions of the high stability of YxAl1 − xN in the wurtzite structure even at high alloy concentrations, experimental studies have revealed significant challenges in achieving the requisite high concentration films. This study demonstrates that strain is an effective parameter on the growth of wurtzite YxAl1 − xN, which can be tuned by engineering growth methods, such as the introduction of different buffer layers. Conversely, difficulties have been encountered in achieving Y concentrations above x = 0.4, despite the incorporation of Y atoms into the layers, with the formation of amorphous structures occurring prior to the predicted structural phase transition to the rock salt crystal. A comprehensive grasp of the structural characteristics of YxAl1 − xN thin films offers invaluable insight that will prove to be beneficial for future research on this material system. [ABSTRACT FROM AUTHOR]

To utilize highly spin-polarized Heusler alloys in practical spintronic devices, the realization of highly textured and structurally ordered polycrystalline thin films under limited annealing temperatures (TA) is critical. Compared to the natural [110]-texture of Heusler alloys, the [001]-texture is considered to be favorable for current-perpendicular-to-plane giant magnetoresistance devices due to the reduced lattice misfit with the face-centered-cubic Ag spacer layers. In this study, we fabricated [001]-oriented polycrystalline Co2FeGa0.5Ge0.5 (CFGG) Heusler alloy films epitaxially grown on a [001]-oriented polycrystalline Ag buffer layer on a thermally oxidized Si substrate, and the microstructure of the [001]-oriented Ag/CFGG bilayer film was investigated in detail. The [001]-oriented Ag films were obtained by introducing N2 into Ar during the sputtering process. The [001]-oriented CFGG films exhibited smooth interfaces, B2 ordering, and a high saturation magnetization close to the theoretical value under relatively low annealing at TA = 300 °C, which are critical for industrial applications such as read heads of hard disk drives. [ABSTRACT FROM AUTHOR]

Growth of GeSn films directly on Si substrates is desirable for integrated photonics applications since the absence of an intervening buffer layer simplifies device fabrication. Here, we analyze the microstructure of two GeSn films grown directly on (001) Si by remote plasma-enhanced chemical vapor deposition (RPECVD): a 1000 nm thick film containing 3% Sn and a 600 nm thick, 10% Sn film. Both samples consist of an epitaxial layer with nano twins below a composite layer containing nanocrystalline and amorphous. The epilayer has uniform composition, while the nanocrystalline material has higher levels of Sn than the surrounding amorphous matrix. These two layers are separated by an interface with a distinct, hilly morphology. The transition between the two layers is facilitated by formation of densely populated (111)-coupled nano twins. The 10% Sn sample exhibits a significantly thinner epilayer than the one with 3% Sn. The in-plane lattice mismatch between GeSn and Si induces a quasi-periodic misfit dislocation network along the interface. Film growth initiates at the interface through formation of an atomic-scale interlayer with reduced Sn content, followed by the higher Sn content epitaxial layer. A corrugated surface containing a high density of twins with elevated levels of Sn at the peaks begins forming at a critical thickness. Subsequent epitaxial breakdown at the peaks produces a composite containing high levels of Sn nanocrystalline embedded in lower level of Sn amorphous. The observed microstructure and film evolution provide valuable insight into the growth mechanism that can be used to tune the RPECVD process for improved film quality. [ABSTRACT FROM AUTHOR]

Nanopore/pillar formation on a Ge substrate can be induced by ion irradiation, which activates the ion beam sputtering and self-organization of point defects. Considering that the size and morphology of nanostructures are dependent on damage production, the irradiation parameters significantly affect nanostructuring. Here, the projected range of incident ions was selected as a parameter to be investigated. The projected range was modified by adding an Au buffer layer on the surface of the substrate, enabling the ions to stop in a shallower layer. The experimental results showed that the deposited Au layer affected the size and morphology of the nanostructures produced by ion irradiation. As a unique morphology, network-like structures were observed on the Au-deposited substrates. These structures were larger than ordinary porous structures. [ABSTRACT FROM AUTHOR]

We investigate magnetron-sputtered In2(OxS1−x)3 compounds acting as an alternative buffer system to the solution-grown CdS or Zn(O,S) buffer layers in Cu(In,Ga)Se2 (CIGS) thin-film solar cells. The influence of the oxygen content on the solar cell performance, microstructure of the mixed systems, bandgap, and band offsets to CIGS is investigated experimentally and also characterized by calculations based on density functional theory. Samples in a series with different chemical compositions ranging from In2S3 to In2O3 are either directly deposited from ceramic targets or from a pure In2S3 target by reactive sputtering by adding O2 in the Ar sputtering gas. The binary compounds In2S3 and In2O3 sputtered at 220 °C substrate temperature from ceramic targets exhibit a crystalline structure, whereas the ternary In2(O,S)3 compounds are either nanocrystalline in the case of In2(O0.25S0.75)3 or amorphous for In2(O0.5S0.5)3 and In2(O0.75S0.25)3. For [O]/([O] + [S]) ratios above 0.25, the cell efficiencies decrease drastically, mainly due to lower open-circuit voltages (VOC). This behavior can be explained by an increase of the negative conduction band offset between the CIGS absorber and the oxygen-rich In2(OxS1−x)3 or In2O3 buffer, resulting in pronounced VOC losses. Adding oxygen to In2S3 with optical bandgap energies of around 2 eV results in a bowing of the values to below 2 eV and finally reaching values of around 2.7 eV for In2O3 if an indirect band transition is assumed. In summary, our results reveal that pronounced oxygen incorporation in In2S3 is not beneficial in terms of CIGS device efficiency because oxygen is electronically inactive and poorly miscible. [ABSTRACT FROM AUTHOR]

Vanadium oxide (VO2) is a strongly correlated material that undergoes an insulator to metal transition at around 68 °C. Unlike other vanadium oxides, VO2 shows phase transition behavior near room temperature, making it an appropriate candidate material for different applications such as thermochromic devices, microwave tunable devices, memory devices, etc. Many practical applications necessitate further tuning of the phase transition temperature to make it more adaptable, either below or above 68 °C. This adaptability is crucial for device efficiency and versatility. The phase transition behavior can be changed by various techniques, including light irradiation, lattice strain modulation, external electric field, and higher and lower valence elements doping. Strain variation is a widely used strategy in the aforementioned methods, and it is achieved by either using suitable substrates or incorporating appropriate buffer layers. This article reviews the various buffer layers used in VO2 thin films and their role in the insulator-metal transition behavior and thermochromic properties, highlighting their significance in enhancing the material's performance in various applications. [ABSTRACT FROM AUTHOR]

The influence of gallium nitride (GaN) and beta-gallium oxide (β-Ga2O3) buffer layers on a laterally scaled AlN/GaN high-electron-mobility transistor (HEMT) using the emerging substrate material silicon carbide (SiC) was investigated in this work. We analyzed the direct-current/radio frequency (DC/RF) performance of AlN/GaN/GaN/AlN/SiC and novel AlN/GaN/β-Ga2O3/SiC HEMTs. Wide-bandgap (Eg = 4.7 eV) β-Ga2O3 material was used as a buffer. Due to the availability of bulk wafer size and low lattice mismatch with group III nitride alloys, β-Ga2O3 is a promising material for future GaN-based HEMT applications. The β-Ga2O3 acts as a natural back barrier, which mitigates buffer leakage current and leads to the confinement of more electrons in the GaN channel. Further, both devices were laterally scaled, and we report their DC/RF performance. The impact of Fe doping in the GaN buffer layer was also studied. The lattice mismatch of β-Ga2O3/SiC was 1.3%, and that for GaN/SiC was 6.4%, which requires the AlN layer as the nucleation layer to avoid stress and strain-related defects. This scaling shows a drastic impact and is also an indicator tool for improving overall device performance. The novel AlN/GaN/β-Ga2O3/SiC HEMT outperformed the alternatives, with a drain current (ID) of 2.71 A/mm, transconductance (gm) of 541 mS/mm, and cut-off frequency (fT) of 391 GHz, with a gate length (LG), gate-to-drain distance (LGD), and gate-to–source distance (LGS) of 50 nm, 0.8 µm, and 0.3 µm, respectively. There was an 18% increase in drain current (2.18 A/mm), 8% improvement in transconductance (503 mS/mm), and 6% improvement in cut-off frequency (373 GHz) when compared to a Fe-doped GaN buffer HEMT. Due to this outstanding performance, the proposed β-Ga2O3 buffer device paves the way for next-generation RF power applications. [ABSTRACT FROM AUTHOR]

This study addresses the stability issues affecting TiO2-MAPbI2-spiro-OMeTAD (n-i-p type) perovskite solar cells, with a focus on degradation mechanisms induced by various environmental stress factors such as illumination, thermal stress, and bias. Using SCAPS-1D simulation software, we systematically investigate the impact of defects at critical locations within the solar cell structure, including the electron transport layer (ETL)/perovskite interface, the bulk perovskite layer, and the hole transport layer (HTL)/perovskite interface. Four types of defects were analyzed: recombination centers (NR), shallow donors (NDT), deep donors (NDP), and shallow acceptors (NAT). The simulation results reveal that deep donor defects in the bulk layer (with a concentration of 1016 cm−3) have the most severe impact on device performance, reducing the power conversion efficiency (PCE) from 22.64% to 2.43%, likely due to thermal degradation. Similarly, defects at the ETL/perovskite interface, with a density of 1014 cm−2, cause a PCE drop to 16.60%, which can be attributed to light-induced degradation. At the perovskite/HTL interface, defects result in a more moderate decline in PCE to 19.47%, potentially linked to hysteresis effects caused by bias stress. To mitigate these stability challenges, we propose two strategies: the incorporation of PbS buffer layers at both interfaces (ETL/perovskite and HTL/perovskite), and the introduction of a graded perovskite layer that includes MAPbSn0.1Cl3 at the rear. These approaches significantly improve the PCE, reducing the degradation effects related to interface and bulk defects. Our findings underscore the critical role of defect management in enhancing the long-term performance of perovskite solar cells. [ABSTRACT FROM AUTHOR]

The urgent demand for efficient renewable energy technologies has driven extensive research into quaternary chalcogenide materials, owing to their outstanding photovoltaic properties and potential for high performance. This study focuses on the design, performance optimization, and comparative analysis of Cu2SrSnS4-based solar cells, with particular emphasis on employing different transition metal dichalcogenide (TMD) buffer layers, specifically MoS2 and WS2. By utilizing SCAPS 1-D simulation software, the research systematically examines the impact of critical parameters such as buffer layer thickness, doping concentrations, and operating temperatures on the solar cell's efficiency and stability. The simulation results demonstrate that the ZnO/MoS2/Cu2SrSnS4 configuration attained the highest efficiency, reaching an impressive 35.6%, significantly surpassing its counterpart with WS2 as the buffer layer, which achieved an efficiency of 29.1%. The findings demonstrate the significance of buffer layer selection and parameter optimization in maximizing the potential of Cu2SrSnS4 solar cells. Ultimately, this research offers valuable insights into the development of high-efficiency, stable photovoltaic technologies, advancing the future of next-generation quaternary chalcogenide solar cells. [ABSTRACT FROM AUTHOR]

Bimetallic selenide heterostructures/carbon composite with specific selenium vacancies and coaxial heterostructures (MoSe 2-x @CoSe 2 -C/GR) has been successfully prepared and demonstrated excellent performance in sodium-ion batteries/ hybrid capacitors. [Display omitted] Sodium-ion batteries (SIBs) and hybrid capacitors (SIHCs) have great potential in related electrochemical energy storage fields. However, the inferior cycling performance and sluggish kinetics of Na+ transport in conventional anodes continue to impede their practical applications. Here, we propose a refined design by utilizing well-organized MoSe 2 nanorods as precursors and introducing a metal–organic framework and graphene (GR), while resulting in the formation of bimetallic selenide heterostructures/carbon MoSe 2-x @CoSe 2 -C/GR (MCCR) composite through electronegativity. The MoSe 2-x /CoSe 2 heterostructure can spontaneously form the built-in electric field to accelerate the charge transport, and the formation of anionic Se vacancies induced by electronegativity in situ can provide more active sites for enhancing sodium storage. The presence of external carbon and graphene can act as buffer layers to suppress the volume expansion of MoSe 2-x /CoSe 2 heterogeneous, and on the other hand, form a conductive network externally to improve electrode conductivity. As anticipated, the MCCR electrode demonstrates superior reversible specific capacity (446 mAh g-1 after 100 cycles) and substantial pseudocapacitance contribution, excellent rate performance in SIB half and full cells. In addition, system electrochemical analysis of multiple ex-situ characterizations elucidates the electrochemical reaction kinetics and transformation mechanism of MCCR electrodes during charging and discharging in depth. When coupled with activated carbon (AC), the MCCR//AC SIHC full hybrid capacitors exhibit impressive cycling stability over 2500 cycles at 1 A g-1 and excellent rate performance, demonstrating their widespread application in energy storage. [ABSTRACT FROM AUTHOR]

A novel block–particle discrete-element simulation method that matches the double medium of overlying rock (OLR) and loose layer (LSL) in coal mining is developed in this study. This method achieves the collaborative failure characteristics of mining damage under the conduction of double media between the OLR and LSL by combining the self-weight stress loading of the LSL and the breakage morphology of the bedrock top. Based on this, the conduction law of high-strength mining damage in the double medium in a western mining area is simulated and analyzed. The combining effect of the OLR breakage morphology and LSL characteristics on the surface-subsidence characteristics is analyzed and verified based on on-site measurements. The results indicate that the OLR is guided by the "double-control layer and thick-soft rock buffer layer" and shows "grouping subsidence", whereas the surface forms collaborative subsidence with the thick-soft rock buffer layer. In the ultra-full mining stage, the surface presents an "asymmetric inverted trapezoidal" subsidence trough shape. The simulation results agree well the on-site measurements in terms of the surface-subsidence and bedrock-subsidence coefficients. The proposed simulation method provides a scientific approach for investigating the micro-conduction mechanism of mining damage under the effect of high-strength mining in western mining areas. It will benefit future investigations pertaining to the characteristics of OLR breakage and surface subsidence under conditions such as LSL thickness and proportion. [ABSTRACT FROM AUTHOR]

In this study, four various titanium dioxide/cuprum oxide (TiO2/CuxO) photovoltaic structures deposited on glass/indium tin oxide (ITO) substrates using the direct-current (DC) reactive magnetron sputtering technique were annealed in air. In our previous work, the deposition parameters for different buffer layer configurations were first optimized to enhance cell fabrication efficiency. In this paper, the effects of post-deposition annealing at 150 °C in air on the optical properties and I-V characteristics of the prepared structures were examined. As a result, significant changes in optical properties and a meaningful improvement in performance in comparison to unannealed cells were observed. Air annealing led to an increase in the reflection coefficient of the TiO2 layer for three out of four structures. A similar increase in the reflection of the CuxO layer occurred after heating for two out of four structures. Transmission of the TiO2/CuxO photovoltaic structures also increased after heating for three out of four samples. For two structures, changes in both transmission and reflection resulted in higher absorption. Moreover, annealing the as-deposited structures resulted in a maximum relative increase in open-circuit voltage (Voc) by 294% and an increase in short-circuit current (Isc) by 1200%. The presented article gives some in-depth analysis of these reported changes in character and origin. [ABSTRACT FROM AUTHOR]

Implementing transition metal nitride (TM-nitride) layers by epitaxy into group-III nitride semiconductor layer structures may solve substantial persisting problems for electronic and optoelectronic device configurations and subsequently enable new device classes in the favorable nitride semiconductor family. As a prominent example, the integration of the group-III-transition metal nitride AlScN enabled an improved performance of GaN based transistor structures due to stronger polarization fields as has been recently demonstrated. For other transition metal nitrides (TMNs) and their alloys with group-III nitrides a range of other interesting properties is expected to enable novel devices and applications. We investigated the compatibility of TM-nitride layers with the growth of GaN-based structures on silicon substrates. As we show TiN layers are compatible and particularly suited as highly conducting, metallic-like buffer layer enabling true vertical conduction without elaborate backside processing. Also, we demonstrate epitaxial growth of alloys based on ScN and AlN as well as of HfN layers on Si(111) substrates by reactive sputtering using high purity gases and targets. Particularly, we analyzed the crystal structure and the quality of Sc-rich AlxSc1-xN. For HfN layers, we find a unique impact on the growth polarity of MOVPE-grown GaN layers on Si(111) which changes to N-polar growth. This represents a simple and technologically scalable approach for N-polar GaN-based layers on Si substrates. [ABSTRACT FROM AUTHOR]

The quality of AlN thin films has an important effect on the performance of bulk acoustic wave (BAW) resonators. In this work, the low lattice mismatch of BaF2 buffer layer with AlN thin films was employed to improve the crystalline quality of AlN thin films. Furthermore, an ethanol assisted epitaxial liftoff (ethanol-ELO) technique based on the BaF2 buffer layer was proposed to lift off AlN thin films from Si substrate, which reduced surface roughness scattering. The ELO technology reduced the damage of AlN thin films and Si wafer during the ELO process due to the selective etching of AlN and BaF2. Utilizing the BaF2 buffer layer, the as-prepared BAW resonators, based on single-crystalline AlN, displayed Q-factor up to 2857, which was 47% higher than that without the BaF2 buffer layer. This study highlights the significant role of the BaF2 buffer layer in enhancing BAW resonators' performance and reducing fabrication costs. [ABSTRACT FROM AUTHOR]

This study investigates the dynamic behaviour between a rockfall and a new anchor cable ribbed rockfall retaining wall on a rock shed, by way of numerical simulations involving the coupling between the PFC3D (discrete-element method (DEM)) and Flac3D (finite-difference method (FDM)) software programs. The novel structure is modelled by the FDM through the zone element, while the rockfall and the buffer layer are modelled by the DEM through the ball element. The numerical results show that three stages of the rockfall movement were modelled: movement, impact and stagnation. The rockfall falls on the slope, impacting the buffer layer on the top of the rock shed, before rebounding to the anchored rockfall retaining walls (with a height lower than 2 m). Then, the stress and deflection can be unified and related to the impact velocity of the rockfall to examine the stability of the structure. The rockfall radius is the dominant of the three parameters (rockfall shape, rockfall radius and impact velocity). While the study focuses on a specific case study, the results provide valuable guidelines for future applications of the proposed combined structure for railway transportation protection. [ABSTRACT FROM AUTHOR]

The electrodeposition of ZnO films was studied using potentiostatic mode in varying conditions including the presence of graphene oxide (GO) as a buffer layer and an additional deposition step. The obtained films were characterized by scanning electron microscopy (SEM), X-ray diffraction (XRD), Fourier transform Infrared (FTIR) spectroscopy, and X-ray photoelectron spectroscopy (XPS). The effect of electrodeposition conditions on the adsorption and photocatalytic properties of ZnO nanostructured films was analyzed by using methylene blue (MB) as a model dye molecule and exposure to UV light. The results indicated a marked effect of GO content in the buffer layer and the duration of nucleation on the properties of electrodeposited ZnO films. Lower GO content and an additional deposition step of 60 s resulted in the best adsorption and photocatalytic activity, these being 7 and 5-folds, respectively, in comparison to ZnO in absence of these adjustments. The MB photodegradation was found to follow first-order kinetics, the rate constant reaching a value of 2.38 × 10−3 min−1. [ABSTRACT FROM AUTHOR]

The baseline Launder-Spalding k - ε model cannot be integrated to the wall. This paper seeks to incorporate the entire law of the wall into the model while preserving the original k - ε framework structure. Our approach involves modifying the unclosed dissipation terms in the k and & equations specifically within the wall layer according to direct numerical simulation (DNS) data. The resulting model effectively captures the mean flow characteristics in both the buffer layer and the logarithmic layer, resulting in robust predictions of skin friction for zero-pressure-gradient (ZPG) flat-plate boundary layers and plane channels. To further validate our formulation, we apply our model to boundary layers under varying pressure gradients, channels experiencing sudden deceleration, and flow over periodic hills, with highly favorable results. Although not the focus of this study, the methodology here applies equally to the k-ω formulation and yields improved predictions of the mean flow in the viscous sublayer and buffer layer. [ABSTRACT FROM AUTHOR]

As application conditions become increasingly demanding and usage becomes more aggressive, the performance of traditional insulated gate bipolar transistor (IGBT) and fast recovery diode (FRD) systems can no longer meet the required specifications. In these systems, FRDs are required to carry load current and allow current to return from the load to the IGBTs. Consequently, the reverse recovery performance of the FRDs significantly restricts the overall efficiency of the system. Therefore, how to predict the reverse recovery characteristics of the FRDs with greater precision has attracted considerable attention. In this context, this paper presents an in-depth investigation of the high-level injection carrier distribution and reverse recovery characteristics of punchthrough P-I-N (PT-PIN) FRD with a buffer layer. Specifically, the research explores the physical properties of the materials, doping concentrations, and the geometric structure of the devices. Furthermore, it takes into account the complex interactions among carrier recombination, diffusion, and drift, leading to the development of a model that delineates the spatial distribution of carriers and their influence on current conduction. Building upon the traditional step-wise analysis method, subsequently, the temporal aspects of the FRDs reverse recovery process were further segmented. Utilizing the derived carrier distribution model, a reverse recovery analytical model was constructed. The model was validated using a 1200 V, 100 A IGBT with 1200 V, 60 A FRD configured in a reverse parallel arrangement, which demonstrated a 5% improvement in prediction accuracy of VR compared with previous models that employed the lumped charge method. Finally, a range of experiments with varying RG, VCC and IF confirmed the broad applicability of this analytical model. [ABSTRACT FROM AUTHOR]

This work provides a comprehensive analysis and evaluation of the interface enhancement achieved by applying a hard carbon coating to graphite, investigating the optimization of lithium deposition and the improvement of fast charging performance. Compared to the original graphite, the hard carbon-coated graphite (HCCG) shows an approximately 8% increase in reversible lithium content, a threefold increase in exchange current density, and a reduction in the Tafel slope to one-quarter of that of the original graphite. [Display omitted] Due to the inherent characteristics of traditional graphite anode material, its lithium diffusion kinetic is significantly constrained, easily leading to a noticeable capacity degradation during rapid charge/discharge cycling. Although modifying the graphite by mixing the hard carbon can effectively enhance its fast-charging performance, yet the underlying mechanism of improvement effect and structure design of interface are still needed to further investigate. To address this research gap, hard carbon-coated graphite (HCCG) material has been designed and synthesized through simple interface engineering, which is aimed to explore and elucidate the optimization mechanisms on fast-charging performance from the graphite interface perspective. According to the electrochemical calculations, the HCCG anode exhibits significant enhancements. Specially, its reversible lithium content is increased by approximately 8 % at various states of charge, its exchange current density is tripled, and its Tafel slope is reduced to one-quarter of the original graphite. Therefore, the HCCG maintains an impressive 86.89 % capacity retention and a high capacity of 202.3 mAh g−1 after 1450 cycles at ultrahigh rate of 5C. These improvements indicate a substantial reduction in electrode polarization during fast charging, which is ascribed to the abundant lithium intercalation pathways and accommodation space provided by the intimate hard carbon coating layer. Moreover, as a "buffer layer," hard carbon coating can accommodate considerable amount of lithium deposited on the graphite surface, effectively mitigating the capacity loss caused by lithium deposition and maintaining effective electrochemical contact without delamination. This comprehensive analysis of hard carbon coating illustrates the improvement mechanism of fast-charging performance, which can offer valuable insights into the dynamic and structural optimization of graphite anode interfaces. [ABSTRACT FROM AUTHOR]

An analytical method is developed for solving the coupled chemo-hydro-mechanical consolidation in a clay buffer layer under time-dependent loading. The coupled governing equations for the chemo-hydro-mechanical process are established in the time and spatial domain first. Then, the governing equations are decoupled into two partial differential equations by introducing two variables. The analytical solutions corresponding to ramp and exponential loadings are finally derived based on the initial and boundary conditions. The developed analytical solutions are verified via comparing with the numerical results simulated by COMSOL Multiphysics. Based on the developed solutions, selected parametric study is carried out to investigate the influence of major parameters and hydraulic boundary conditions on the contaminants transport and pore water pressure dissipation in buffer clay layer. The results show that the major parameters have effects on the generation and dissipation of pore pressure, while only effective coefficient of diffusion, coefficient of ultrafiltration, and relative change of total density of pore liquid significantly affect the contaminant migration process. Compared with a single drainage boundary, the pore pressure dissipation and contaminant migration in a double drainage soil layer are much faster. The longer the loading time of mechanical loading, the more significant the negative pore pressure caused by the concentration gradient. [ABSTRACT FROM AUTHOR]

Various forms of thermal degradation of light emitters based on III-nitrides have been observed, with no clear conclusion about the mechanism. We investigate the non-radiative carrier lifetime in GaInN/GaN single quantum wells (SQWs) with various emission wavelengths and its relation to the growth conditions. We observe that the non-radiative lifetime in SQWs increases exponentially with decreasing buffer and cladding layer growth temperature. As a first conclusion, diffusion of point defects leading to non-radiative recombination is a universal mechanism present during III-nitride growth. Second, this is likely a predominant mechanism for thermal degradation observed while growing layers on top of the quantum well, e.g., a p-layer, and after post-growth annealing. Performance and reliability of devices can be improved by properly controlling point defect diffusion. [ABSTRACT FROM AUTHOR]

Stereolithography (SLA) shows great market potentials in preparing ceramic shells for precision casting due to its capability of rapid producing complex molds with smooth surface and accurate dimension. However, the cracks of ceramic shell derived from the distinct thermal expansion coefficients of the SLA photosensitive resin and the ceramic shell hinders its wide application in the industry. In this work, a buffer layer integration (BLI) is demonstrated as an effective countermeasure. A film of carnauba wax with a thickness of ∼100 μm is manipulated uniformly coated on the surface of SLA photosensitive resin prototype, which is designed to release the thermal stress during the dewaxing and sintering process. After sintering, the BLI-ceramic shell shows no obvious cracks on the surface in comparison with that of regular ones, and the surface quality of the face-coat remains the same, demonstrating the enhancement of crack resistance. The finite element simulation shows the results in agree with the experiments, which suggests that the carnauba BLI can supply sufficient buffering space when its thickness is over 100 μm and keeps intimate contact with the matrix. The casting process was performed onto the BLI-ceramic shells, and the castings (30 mm) with high precision (CT 8) and good surface (Ra 1.975) were obtained. This facile and straightforward BLI process is believed promising industrially. [ABSTRACT FROM AUTHOR]

Li1.3Al0.3Ti1.7(PO4)3 (LATP) is a cost‐effective representative solid‐state electrolyte (SSE) with high ionic conductivity and has gradually become a hotspot for all‐solid‐state lithium metal batteries (ASLMBs). Nevertheless, its practicalization has been challenged by the intertwined electro‐chemo‐mechanical interface issues of Li/SSE, such as penetration of Li dendrites, poor physical contact, and poor interfacial compatibility. Thus, it is essential to design interfacial management from an electro‐chemo‐mechanical perspective to guarantee the stability of Li/SSE interface bottom‐to‐up and prolong the cyclic life of ASLMBs with higher electrochemical performance. Here, an electro‐chemo‐mechanical buffer layer with softer mechanics and higher ionic conductivity is constructed on LATP surface by the spontaneous reaction between Li metal and an as‐prepared Ti‐LiF thin film using the magnetron sputtering. Introducing an electro‐chemo‐mechanical buffer layer fosters cross‐interfacial migration of Li‐ions and dissipates interface stress from the growth of Li metal to suppress the early failure of the SSE, realizing long‐term interfacial stability. In consequence, Li[Ni0.8Co0.1Mn0.1]O2|Ti‐LiF LATP|Li ASLMBs deliver a high specific capacity of 163.1 mAh g−1 at 0.2 C, with a capacity retention ratio of 96.1% after 150 cycles. Therefore, the interfacial design from electro‐chemo‐mechanics has been proposed innovatively to open‐up a broad avenue for applying ASLMBs to next‐generation energy storage systems. [ABSTRACT FROM AUTHOR]

ABSTRACT In this study, silver nanowire covered with graphene (AgNW/Graphene) transparent conducting electrodes (TCE) were developed as bendable TCE instead of conventionally used indium tin oxide (ITO) for flexible photovoltaic applications. CVD‐grown graphene films were transferred from a Cu foil onto a spin‐coated AgNW TCE. AgNW/Graphene TCE exhibited lower electrical resistance than 10 Ω and high optical transmission of approximately 80% at visible wavelengths before and after bending of 20 cycles at a radius of 15 mm. Thermal tolerance of AgNW was drastically improved by protecting silver nanowires with graphene from oxidation at the 300°C air annealing test. ZnMgO/Se thin film photovoltaic devices with AgNW/graphene were successfully demonstrated by insertion of a sol‐gel ZnO buffer layer in order to protect AgNW/graphene from sputtering bombardment. [ABSTRACT FROM AUTHOR]

BaTiO3 (BTO) thin films were deposited on LaNiO3 (LNO)/SiO2/Si substrates by magnetron sputtering, and the LNO thin film was deposited as a bottom electrode and a buffer layer. The bipolar resistive switching (RS) behaviors have been observed in the Al/BTO/LNO devices, and the effect of illumination conditions on the RS behavior was investigated. The set voltage was effectively reduced by the photogenerated carrier, and a greatly improved OFF/ON resistance ratio of ∼120 was achieved under high light conditions. The Al/BTO/LNO devices showed good endurance and retention performance. The conduction mechanisms of the Al/BTO/LNO devices have been discussed based on the migration of defects and photogenerated carriers. These results facilitated a deeper study of BTO‐based multifunctional storage devices and demonstrated the tunable photoresponse characteristic. [ABSTRACT FROM AUTHOR]

Heterostructures with InAs/InGaAs quantum dots and InxGa1–xAs/GaAs(001) metamorphic buffer layers are grown by molecular-beam epitaxy. The structures are designed to obtain single-photon emission in the telecommunication C-band wavelength range. The possibility of reducing the thickness of the InxGa1–xAs graded layer in order to form efficient microcavity structures with a cavity length as small as two wavelengths is examined. The structures with metamorphic buffer layers grown on top of an Al0.9Ga0.1As/GaAs distributed Bragg reflector are grown and characterized by cross-sectional transmission electron microscopy and photoluminescence spectroscopy. [ABSTRACT FROM AUTHOR]

In this study, we used a starch paste stabilizer to synthesize ZnSe: Mn/ZnS- Starch and ZnSe/ZnS: Mn/ZnS-starch quantum dot (QDs) in a non-toxic aqueous solvent. The -CH2-OH group of the starch paste promotes dispersibility and improves the compatibility of quantum dots with antibodies, its bonding is observed in the FTIR spectrum. Besides, the Mn-doped ZnS buffer shell with various concentrations (1, 3, 5, 7, and 9%) influence structure, optical, and photoluminescence of QDs properties were investigated in detail. The greatest luminescence intensity is achieved at a molar ratio of 3% Mn2+/Zn2+. Moreover, the ZnS: Mn buffer shell helps to enhance the fluorescence intensity and quantum yield (QY) of the ZnSe/ZnS: Mn/ZnS QDs, which are higher than ZnSe: Mn/ZnS-starch QDs. Through protein A and EDC bridging, ZnSe/ZnS:3%Mn/ZnS- Starch resulted in good signal and sensitivity, with no toxicity to E. coli O157:H7 and MRSA strains. [ABSTRACT FROM AUTHOR]

During the development of the disposal concept in a crystalline massif of the Russian Federation, a question arose regarding the selection of the most suitable types of bentonite for a buffer layer. Data on the composition, structure, surface, and adsorption properties of four promising deposits have been obtained. The correlations between genesis and specific surface area (SSA) revealed in this study indicate that bentonites of volcanogenic-sedimentary origin have lower SSA in comparison with those of sedimentary and hydrothermal origin. The main contribution to the charge of the 2:1 layer is made by isomorphic substitutions in the tetrahedral sheet, which directly affects the sorption properties of bentonites. The influence of smectite structure on adsorption properties have been described. In particular, the dependencies between the layer charge and cation exchange capacity (CEC) have been analyzed. At the same time, the research indicates that, unlike the CEC, the specific surface area of a deposit is determined by its geological history. Special attention is being paid to refining methodological approaches for deriving crystal chemical formulae of smectites, which will be needed in the future for modelling changes in bentonite over a long-term perspective. [ABSTRACT FROM AUTHOR]

In the current work, ZnO film (~ 143 nm) is deposited on the CMOS compatible Si substrate by using RF sputtering technique to form a p-n type heterojunction device and further, thin buffer layer of TiO2 (~ 52 nm) is inserted in between ZnO and Si to reduce the interfacial defects remarkably in ZnO/TiO2/Si bilayer heterojunction for UV/Visible sensing applications. Smooth interface, and highly crystallite qualities of TiO2-brookite and ZnO-hexagonal wurtzite phases are observed from atomic force microscopy (AFM) and Field-emission gun scanning electron microscopy (FEG-SEM) and X-ray diffraction (XRD), respectively. X-ray photoelectron spectroscopy (XPS) clarifies the chemical states of elements, which indicate a significant amount of the reduction in oxygen vacancies after insertion of the TiO2 thin layer. An enhanced absorption in UV region and slight red shift in emission are observed in UV-Visible spectroscopy and Photoluminescence (PL) plots for TiO2/ZnO bilayer heterojunction, and oxygen related complex defects are reduced due to TiO2 insertion. Finally, Current-voltage (I-V) measurements demonstrate the dark current reduction in ZnO/Si heterojunction with TiO2 incorporation and such heterojunction exhibits photovoltaic behavior under specific wavelengths (380 nm and 420 nm). A superior responsivity (0.17 A/W), detectivity (7.80 × 10¹³ Jones) with rapid response speed (< 1 s) at zero bias are achieved in the UV-A/Visible wavelength range for ZnO/TiO2/Si heterojunctions. The corresponding photo-carrier generation and transport mechanism are analyzed in detail by using corresponding energy band diagram. Therefore, all the results indicate that such TiO2 thin layer inserted ZnO/Si heterojunction may provide a cost-effective feasible design strategy for the development of interfacial defect less, self-powered wavelength selective UV/Visible detectors in recent future. [ABSTRACT FROM AUTHOR]

The conventional cadmium sulfide (CdS) window/buffer layer in photovoltaic cells is environmentally hazardous because of the poisoning of cadmium (Cd). Alternatively, ZnS is more environmentally friendly than CdS and has a larger band gap, which makes it a potential candidate for window/buffer layers. In this study, ZnS thin films were deposited on glass substrates by a spin coating process and annealed at three (250 °C, 350 °C, and 450 °C) different temperatures. The XRD patterns confirmed that all the spin coated films had mixed wurtzite and cubic structures with a preferred orientation along the (111) plane of the predominant cubic phase. The highest crystallite size and lowest dislocation density were found at 350 °C annealing temperature due to the narrow, sharp and high intensity diffraction peak compared with those at 250 °C and 450 °C annealing temperatures. The SEM results indicate that the surface of the ZnS film annealed at 350 °C has a better surface coverage area with good uniformity, and is more homogeneous with a minimum amount of pinholes, voids and cracks than the other samples annealed at 250 °C, and 450 °C. The estimated optical band gap was determined to be between 3.957 and 3.991 eV. The calculated electrical resistivity values are on the order of 10 4 Ω cm. All the findings revealed that the film annealed at 350 °C presented good material properties for utilizing as buffer layer in thin film solar cells. [ABSTRACT FROM AUTHOR]

Purpose: The present study scrutinizes the relative performance of various near-wall treatments coupled with two-equation RANS models to explore the turbulence transport mechanism in terms of the kinetic energy budget in a plane wall jet and the significance of the near-wall molecular and turbulent shear, to select the best combination among the models which reveals wall jet characteristics most efficiently. Design/methodology/approach: A two-dimensional steady incompressible plane wall jet in a quiescent surrounding is simulated using ANSYS-Fluent solver. Three near-wall treatments, namely the Standard Wall Function (SWF), Enhanced Wall Treatment (EWT) and Menter-Lechner (ML) treatment coupled with Realisable, RNG and Standard k-e models and also the Standard and Shear-Stress Transport (SST) k-ω models are employed for this investigation. Findings: The ML treatment slightly overestimated the budget components on an outer scale, whereas the k-ω models strikingly underestimated them. In the buffer layer at the inner scale, the SWF highly over-predicts turbulent production and dissipation and k-ω models over-predict dissipation. Appreciably accurate inner and outer scale k-budgets are observed with the EWT schemes. With a sufficiently resolved near-wall mesh, the Realisable model with EWT exhibits the mean flow, turbulence characteristics and turbulence energy transport even better than the SST k-ω model. Originality/value: Three distinct near-wall strategies are chosen for comparative performance analysis, focusing not only on the mean flow and turbulence characteristics but the turbulence energy budget as well, for finding the best combination, having potential as a viable and low-cost alternative to LES and DNS for wall jet simulation in industrial application. [ABSTRACT FROM AUTHOR]

Herein, the 1D Solar Cell Capacitance Simulator software is used to perform numerical analysis of thin‐film solar cells with Cu2ZnSnS4, Cu2BaSnS4, Cu2FeSnS4, and Cu2MnSnS4 absorber layers. The main goal is to investigate the impact of parameters, such as absorber layer thickness, acceptor density, buffer layer, bandgap, and donor density, on the efficiency of these solar cells. The absorber layer investigation entails varying the thickness and the acceptor density to evaluate their influence on the efficiency of the solar cell. A new zinc oxide sulfide (Zn(O,S)) buffer layer is also introduced instead of the conventional cadmium sulfide (CdS) buffer layer. The Zn(O,S) bandgap and its donor density, which are investigated in terms of how they affect the efficiency of the solar cells, have been varied. The optimal values for the thickness of the absorber layer, acceptor density, and the bandgap of the buffer layer are calculated. Subsequently, the donor density is evaluated to find any potential defects that may affect the efficiency of the solar cell. These results confirm that Zn(O,S) can be utilized as a buffer layer. This study concludes that Cu2ZnSnS4, Cu2BaSnS4, and Cu2MnSnS4 absorber layers have superior efficiency in comparison with Cu2FeSnS4. [ABSTRACT FROM AUTHOR]

Herein, a model is proposed for measuring the structural defects size r0 in an ultrathin magnetic layer with perpendicular magnetic anisotropy. Based on the observations of magnetic domains in Ta/Pt/Co/Pt ultrathin films, using polar magneto‐optical Kerr effect microscopy and measurements of their magnetic anisotropies, the correlation between magnetic domains size D and structural defects size r0, as well as the defects concentration parameter αK, which designates the degree of pinning, has been modeled. The average r0 value found is high in the sample with unannealed buffer layers and considerably decreases with annealing. It is 6.17 nm with unannealed Ta/Pt buffer layers, 1.06 nm in sample with Ta/Pt buffer layers annealed at 423 K, and 0.49 nm in that with buffer layers annealed at 573 K. The significant drop of r0 is in good agreement with the high depinning noted with buffer layers annealing in recent work. [ABSTRACT FROM AUTHOR]

In this paper, AlGaN/GaN high electron mobility transistors (HEMTs) with different thicknesses of unintentional doping GaN (UID-GaN) channels were compared and discussed. In order to discuss the effect of different thicknesses of the UID-GaN layer on iron-doped tails, both AlGaN/GaN HEMTs share the same 200 nm GaN buffer layer with an Fe-doped concentration of 8 × 1017 cm−3. Due to the different thicknesses of the UID-GaN layer, the concentration of Fe trails reaching the two-dimensional electron gas (2DEG) varies. The breakdown voltage (Vbr) increases with the high concentration of Fe-doped in GaN buffer layer. However, the mobility of the low concentration of the Fe-doped tail is higher than that of the high concentration of the Fe-doped tail. Therefore, the effect of different thicknesses of UID-GaN on the DC and radio frequency (RF) performance of the device needs to be verified. It provides a reference to the epitaxial design for high-performance GaN HEMTs. [ABSTRACT FROM AUTHOR]

Lead thin film capacitors with high energy storage performance have attracted increasing interest in their applications in modern devices. In this study, the energy storage performances of Pb0.95La0.02(Zr0.5Sn0.5)O3 antiferroelectric thin films were enhanced by incorporating Al2O3 and HfO2 buffer layers. The electrical properties and energy storage characteristics of antiferroelectric thin films with different buffer layers were analyzed to study the impact of buffer layers on energy storage performance. After the incorporation of Al2O3 and HfO2 buffer layers, the breakdown field strength (Eb) of the films were significantly increased and the leakage current densities were greatly reduced with the ohmic conduction range widened at low electric fields. As a result, the energy storage density of films with Al2O3 and HfO2 buffer layers increased significantly from 10.07 to 31.54 and 22.63 J/cm3, respectively. By analyzing the leakage current, it was found that the Poole–Frenkel emission was significantly suppressed by the Al2O3 buffer layer, while the HfO2 buffer layer had a limited effect on the conduction mechanisms, which resulted in the better energy storage performance of those films with Al2O3 buffer layers. The results demonstrate that the improvement of energy storage performance is attributed to the leakage current emission mechanism affected by the buffer layer. [ABSTRACT FROM AUTHOR]

Perovskite solar cells (PSCs) characterized by high energy conversion efficiency (ECE) and low manufacturing costs, exhibit promising potential for commercialization in the near term. For commercialization, it is very important to prevent the decomposition of perovskite by ultraviolet (UV) radiation in the air environment. Also, the mesoscopic architecture of PSCs presents considerable opportunities for the solar cell industry, offering potential for recycling of spent photocatalytic materials such as TiO2, and exploration of new energy resources. To solve these problems, therefore, this study introduces a strategy to mitigate these challenges using a crystalline Al-doped TiO2 buffer layer as the electron transport layer (ETL) in conjunction with a mesoporous TiO2 layer in the fabrication of PSCs. Among various Al concentrations in the crystalline Al-doped TiO2 buffer layer fabricated via spin-coating, an optimum concentration of 7 mol% Al yielded the highest cell performance in the specific perovskite solar cell structure. These solar cells exhibited an impressive ECE of 11.87%, representing a substantial enhancement of nearly double the ECE (6.37%) achieved with the conventional ETL. This remarkable improvement can be attributed to the passivation effect of the newly developed ETL, which combines a crystalline Al-doped TiO2 buffer layer with a mesoporousTiO2 layer. Electrochemical impedance spectroscopy (EIS) analysis was performed in conjunction with theoretical calculations of charge transport parameters to substantiate this claim. [ABSTRACT FROM AUTHOR]

Bow-tie diodes on the base of modulation-doped semiconductor structures are often used to detect radiation in GHz to THz frequency range. The operation of the bow-tie microwave diodes is based on carrier heating phenomena in an epitaxial semiconductor structure with broken geometrical symmetry. However, the electrical properties of bow-tie diodes are highly dependent on the purity of the grown epitaxial layer—specifically, the minimal number of defects—and the quality of the ohmic contacts. The quality of MBE-grown semiconductor structure depends on the presence of a buffer layer between a semiconductor substrate and an epitaxial layer. In this paper, we present an investigation of the electrical and optical properties of planar bow-tie microwave diodes fabricated using modulation-doped semiconductor structures grown via the MBE technique, incorporating either a GaAs buffer layer or a GaAs–AlGaAs super-lattice buffer between the semi-insulating substrate and the active epitaxial layer. These properties include voltage sensitivity, electrical resistance, I–V characteristic asymmetry, nonlinearity coefficient, and photoluminescence. The investigation revealed that the buffer layer, as well as the illumination with visible light, strongly influences the properties of the bow-tie diodes. [ABSTRACT FROM AUTHOR]

Mechanically flexible substrates are increasingly utilized in electronics and advanced energy technologies like solar cells and high-temperature superconducting coated conductors (HTS-CCs). These substrates offer advantages, such as large surface areas and reduced manufacturing costs through reel-to-reel processing, but often lack the surface smoothness needed for optimal performance. For HTS-CCs, specific orientation and high crystalline quality are essential, requiring buffer layers to prepare the amorphous substrate for superconductor deposition. Techniques, such as mechanical polishing, electropolishing, and chemical-mechanical polishing, can help achieve an optimally levelled surface suitable for the subsequent steps of sputtering and ion-beam-assisted deposition (IBAD) necessary for texturing. This review examines Solution Deposition Planarization (SDP) as a cost-effective alternative to traditional electro-mechanical polishing for HTS coated conductors. SDP achieves surface roughness levels below 1 nm through multiple oxide layer coatings, offering reduced production costs. Comparative studies demonstrate planarization efficiencies of up to 20%. Ongoing research aims to enhance SDP's efficiency for industrial applications in CC production. [ABSTRACT FROM AUTHOR]

The squeezing deformation of surrounding rock is an important factor restricting the safe construction and long-term operation of tunnels when a tunnel passes through soft strata with high ground stress. Under such soft rock geological conditions, the large deformation of the surrounding rock can easily lead to the failure of supporting structures, including shotcrete cracks, spalling, and steel arch distortion. To improve the lining support performance during the large deformation of squeezed surrounding rock, this work selects aluminum foam with densities of 0.25 g/cm3, 0.42 g/cm3 and 0.61 g/cm3 as the buffer layer material and carries out uniaxial confined compression tests. Through the evaluation and analysis of energy absorption and the comparison of the yield pressure of aluminum foam with those of other cushioning materials and yield pressure support systems, the strength, deformation and energy absorption of aluminum foam with a density of 0.25 g/cm3 meet the yield pressure performance requirements. The numerical model of the buffer layer yielding support system is then established via the finite element analysis software ABAQUS, and the influence of the buffer layer setting on the lining support is analyzed. Compared with the conventional support scheme, the addition of an aluminum foam buffer layer can reduce the stress and deformation of the primary support and secondary lining. The maximum and minimum principal stresses of the primary support are reduced by 13% and 15%, respectively. The maximum and minimum principal stresses of the secondary lining are reduced by 15% and 12%, respectively, and the displacement deformation of the secondary lining position is reduced by 15%. In summary, the application of aluminum foam buffer layer can reduce the stress and deformation of the primary support and secondary lining, improve the stress safety of the support and reduce the deformation of the support. [ABSTRACT FROM AUTHOR]

A novel AlGaN/GaN high-electron mobility transistor (HEMT) is put forward to promote its breakdown characteristics and anti-single-event transient (SET) effect. The features of the proposed device are a hybrid GaN/AlN buffer layer and a uniform-groove high-k passivation layer between the gate and drain electrodes (HGKB-HEMT). First, the uniform-groove high-k passivation layer not only reduces the peak electric field at the gate edges, but also modulates the electric field distribution between the gate and drain. Therefore, the breakdown voltage (BV) and the anti-SET effect show a great improvement. Second, the buffer leakage current was effectively reduced by the hybrid buffer layer, resulting in a further increase in the BV. The BV of the HGKB-HEMT reached 1672 V, which is 82.7% higher than the conventional GaN HEMT, and the peak drain current induced by the SET effect of the HGKB-HEMT decreased by 60.7% at VDS = 50 V. Moreover, the channel current of the HGKB-HEMT increased slightly and the on-state resistance decreased. [ABSTRACT FROM AUTHOR]

The Adaptive Solvent-Scaling (AdSoS) scheme [J. Chem. Phys. 155 (2021) 094107] is an adaptive-resolution approach for performing simulations of a solute embedded in a fine-grained (FG) solvent region surrounded by a coarse-grained (CG) solvent region, with a continuous FG ↔ CG switching of the solvent resolution across a buffer layer. Instead of relying on a distinct CG solvent model, AdSoS is based on CG models defined by a dimensional scaling of the FG solvent by a factor s, accompanied by the s-dependent modulation of its mass and interaction parameters. The latter changes are designed to achieve an isomorphism between the dynamics of the FG and CG models, and to preserve the dispersive and dielectric solvation properties of the solvent with respect to a solute at FG resolution. As a result, the AdSoS scheme minimizes the thermodynamic mismatch between different regions of the adaptive-resolution system. The present article generalizes the scheme initially introduced for a pure atomic liquid in slab geometry to more practically relevant situations involving (i) a molecular dipolar solvent (e.g., water); (ii) a radial geometry (i.e., spherical rather than planar layers); and (iii) the inclusion of a solute (e.g., water molecule, dipeptide, ion, or ion pair). [ABSTRACT FROM AUTHOR]

An efficient carrier compensation mechanism in semiconductor layers by Fermi-level engineering is demonstrated using the modulation-doping of a deep acceptor and a shallow donor. The punch-through of the depletion region across the whole stack of modulation-doped layers shifts the Fermi level closer toward the midgap position, resulting in the compensation of residual background free carriers. The method represents an alternative to achieve semi-insulating properties in semiconductor materials where a suitable deep acceptor or donor state at the midgap position is not available. We demonstrate the applicability of the concept with a commercially important GaN case study using carbon (deep acceptor) and Si (shallow donor) doping. A strong enhancement of breakdown field strength and reduced charge pileup effects are observed due to the efficient pinning of the Fermi level. [ABSTRACT FROM AUTHOR]

Inclusion of Si atoms to the growth surface during the molecular beam epitaxy of Ge and Sn to form a SiGeSn alloy was identified as a reactive surface species and as a means to compensate strain, which allowed for the subsequent growth of GeSn alloys with high Sn content. The development of a SiGeSn virtual substrate having a 15% Sn concentration and lattice parameter larger than 5.72 Å is demonstrated, using atomic force microscopy, x-ray reciprocal space mapping, and transmission electron microscopy, as a method for the direct growth of thick (>500 nm) fully relaxed GeSn alloys with greater than 10% Sn. This buffer layer enables the monolithic integration of GeSn with silicon for optoelectronic applications, as the SiGeSn virtual substrate allows for selective chemical etching of GeSn, which is important for device fabrication. [ABSTRACT FROM AUTHOR]

Defects in pulsed-laser deposition grown $\kappa{\hbox -}{\rm Ga}_2{\rm O}_3$ have been investigated using thermal admittance spectroscopy and secondary ion mass spectrometry (SIMS). A $\kappa {\hbox -}{\rm Ga}_2{\rm O}_3$ film was grown on either a tin-doped indium oxide or an aluminum-doped zinc oxide buffer layer on a sapphire substrate functioning as back contact layer in vertical diode structures. In both sample types, a distinct signature in the capacitance signal was observed in the temperature range of 150–260 K. The corresponding defect charge-state transition level, labeled $E_0$ , was found to exhibit an activation energy of 0.21 eV. Potential candidates for the $E_{0}$ level were investigated using a combination of SIMS and hybrid-functional calculations. SIMS revealed the main impurities in the sample to be tin, silicon, and iron. The hybrid-functional calculations predict the acceptor levels of substitutional iron to lie 0.7–1.2 eV below the conduction band minimum depending on Ga-site, making ${\rm Fe}_{{\rm Ga}}$ an unlikely candidate for the $E_0$ level. Furthermore, Si as well as Sn substituting on the sixfold coordinated Ga2 site and the fivefold coordinated Ga3 and Ga4 sites are all shallow donors in $\kappa$ - ${\rm Ga}_2{\rm O}_3$ , similar to that of $\beta$ - ${\rm Ga}_2{\rm O}_3$. Sn substituting on the fourfold Ga1 site is, however, predicted to have levels in the bandgap at 0.15 and 0.24 eV below the conduction band minimum, in accordance with the extracted activation energy for $E_{0}$. Thus, we tentatively assign ${\rm Sn}_{{\rm Ga}1}$ as the origin of the $E_0$ level. [ABSTRACT FROM AUTHOR]

This study introduces a novel method for achieving highly ordered‐crystalline In2‐xGaxO3 [0 ≤ x ≤ 0.6] thin films on Si substrates at 250 °C using plasma‐enhanced atomic‐layer‐deposition (PEALD) with dual seed crystal layers (SCLs) of γ‐Al2O3 and ZnO. Field‐effect transistors (FETs) with random polycrystalline In2‐xGaxO3 channels (grown without SCLs) show a mobility (µFE) of 85.1 cm2 V−1s−1, attributed to high indium content. In contrast, FETs with highly ordered In2‐xGaxO3 grown via SCLs exhibit superior performance, with µFE reaching 95.5 cm2 VV−1s−1 and enhanced reliability due to the uniform growth of high‐quality bixbyite films. The role of γ‐Al2O3 and ZnO SCLs in enabling this growth and the correlation between cation composition, crystalline structure, and electrical properties are comprehensively analyzed. This approach provides new insights into the high‐quality bixbyite In2‐xGaxO3 system, offering an alternative to conventional amorphous or polycrystalline structures. The highly ordered crystalline structure paves the way for advanced applications in 3D heterogeneous semiconductor chips, expanding beyond displays to include memory, logic, and artificial intelligence devices. [ABSTRACT FROM AUTHOR]

Antimony selenide (Sb 2 Se 3) based heterojunction photocathodes have recently received an increased attention, largely due to their outstanding performances for hydrogen production through photoelectrochemistry (PEC) water splitting. The PEC water splitting process encompasses both physical and electrochemical processes. The physical process is capable of generating a photo-voltage, which can drive the photo-generated electrons transport to the electrode/electrolyte interface through the p-n junction. However, unlike traditional photovoltaic device, the protective layer and co-catalyst will also affect the electrical performance of device, resulting in a decrease in PEC performances and stability. How to optimize the electrical properties of the photoelectrode is a concern. In this work, devoted to Sb 2 Se 3 /TiO 2 photocathode structures, the photovoltaic performances of a photocathode were modeled and analyzed from three aspects: p-n junction, back contact, and transition layer between TiO 2 and co-catalyst, using the SCAPS-1D software and a realistic set of material parameters. Based on reported optimization strategy, tthe interface electrical characteristics of photocathode were studied by adjusting energy band, donor/acceptor density, defect density, electron affinity, and other parameters. A low-cost and easy to implement optimization strategy was proposed, which used Cd 1-x Zn x S as the buffer layer between p-n junctions, W-doped TiO 2 as the transition between TiO 2 /co-catalyst, and Sn-doped Sb 2 Se 3 as the back surface layer to suppress the carrier recombination. The optimized photocathode can theoretically obtain photoelectric conversion efficiency of 17.01%–17.14% and a maximum J sc of 38.79 mA/cm2, exhibiting the potential to obtain a large photocurrent in the photoelectrochemical water splitting process. • Sb 2 Se 3 based photocathode was simulated by the SCAPS software. • CdS buffer layer needs to raise the conduction band energy level to increase V oc. • CBO and back electric field can reduce back recombination. • Lowering the conduction band energy level of TiO 2 can suppress the interface barrier. [ABSTRACT FROM AUTHOR]