Band Diagram Research Articles

Multilayered heterojunction-based zinc oxide nanoneedles/polyaniline/titania nanoparticles as a self-powered ultraviolet light photodetector

Nowadays, self-powered ultraviolet photodetectors (SPDs) with improved photoresponse features have attracted considerable attention due to their great pivotal applications in military and civilian fields. In the present work, for the first time, we investigate and report the construction and photoresponse features of a SPD based on multilayered heterojunction-based zinc oxide nanoneedles/polyaniline/titania nanoparticles (ZET). The structure, morphology, and optical properties of the ZET and its components were comprehensively investigated. A significant dependence was observed between the changes in I-V characteristics of the ZET-based SPD (SPZ) and the temperature change, resulting in a short reverse saturation current, proper ideality factor, and low dark current. I-V characteristics of the SPZ revealed nonlinear asymmetric rectifying behavior with the improved current under the influence and increase of power densities (PDiss) of ultraviolet (UV) light irradiation. Moreover, the self-powered feature of the SPZ was confirmed by the generation of short-circuit current and notable contrast ratio under UV light illumination at zero bias voltage. The device displayed remarkable photoresponsivity of 4.46A/W, high significant normalized detectivity of 63.1×1012Jones, good fill factor of 50.64%, and excellent external quantum efficiency of 1514% at the PDis of 0.77mW/cm2. In addition, the SPZ exposed a short rise time of 540 ms, a high maximum photocurrent of 99.9µA, and a significant gain dynamic range of 499.5 at PDis of 19.11mW/cm2. Finally, the imaginable mechanism of the current generation in our hand-made device was discussed in detail by exerting a standard thermionic emission-diffusion model and energy band diagram.

A theoretical study on the insights of designing and optimization of a CsSn(IxBr1-x)3 based solar cell

This work focuses on designing and optimizing a lead-free perovskite solar cell. The significance of band gap grading in obtaining better performance of the solar cell was studied in detail with CsSn(IxBr1-x)3 () being used as the active absorber material. The device showed a maximum power conversion efficiency (PCE) of when the interfacial defects were not considered. The optimum thickness was obtained to be 1 μm, and the corresponding doping concentration was 1020 cm-3. Further, a detailed discussion on the band diagrams, electric fields, and different recombination processes has been carried out in this work to get an idea about the varying PCE values at different operating conditions. The presence of Shockley-Read-Hall (SRH) recombination at various temperature values was observed, which partially contributed to the reduction in PCE values at higher temperatures. This work also discusses briefly about the probable losses involved with the device, which may be considered as the plausible reasons for obtaining PCE values less than the SQ limit. This information opens up a wide window for researchers to experimentally fabricate solar cells with proper cautions so that a device with PCE value exceeding Shockley Quisser (SQ) limit can be made available commercially.

Spin injection and detection in a Si-based ferromagnetic tunnel junction: Theoretical model based on the band diagram and experimental demonstration

Spin injection and detection in a Si-based ferromagnetic tunnel junction: Theoretical model based on the band diagram and experimental demonstration

Analysis of Influence of Excitation Source Direction on Sound Transmission Loss Simulation Based on Alloy Steel Phononic Crystal

As a type of locally resonant phononic crystal, alloy steel phononic crystals have achieved notable advancements in vibration and noise reduction, particularly in the realm of low-frequency noise. Their exceptional band gap characteristics enable the efficient reduction of vibration and noise at low frequencies. However, the conventional transmission loss (TL) simulation of finite structures remains the benchmark for plate structure TL experiments. In this context, the TL in the XY-direction of phononic crystal plate structures has been thoroughly investigated and analyzed. Given the complexity of sound wave incident directions in practical applications, the conventional TL simulation of finite structures often diverges from reality. Taking tungsten steel phononic crystals as an example, this paper introduces a novel finite element method (FEM) simulation approach for analyzing the TL of alloy steel phononic crystal plates. By setting the Z-direction as the excitation source, the tungsten steel phononic crystal plate exhibits distinct responses compared to excitation in the XY-direction. By combining energy band diagrams and modes, the impact of various excitation source directions on the TL simulations is analyzed. It is observed that the tungsten steel phononic crystal plate exhibits a more pronounced energy response under longitudinal excitation. The TL map excited in the Z-direction lacks the flat region present in the XY-direction TL map. Notably, the maximum TL in the Z-direction is 131.5 dB, which is significantly lower than the maximum TL of 298 dB in the XY-direction, with a more regular peak distribution. This indicates that the TL of alloy steel phononic crystals in the XY-direction is closely related to the acoustic wave propagation characteristics within the plate, whereas the TL in the Z-direction aligns more closely with practical sound insulation and noise reduction engineering applications. Therefore, future research on alloy steel phononic crystal plates should not be confined to the TL in the XY-direction. Further investigation and analysis of the TL in the Z-direction are necessary. This will provide a novel theoretical foundation and methodological guidance for future research on alloy steel phononic crystals, enhancing the completeness and systematicness of studies on alloy steel phononic crystal plates. Simultaneously, it will advance the engineering application of alloy steel phononic crystal plates.

A comparative numerical simulation study of CIGS solar cells with distinct back surface field layers for enhanced performance

The objective of this study is to explore the impact of various back surface field (BSF) layers including copper aluminium oxide (CuAlO2), Copper Antimony Sulphide (CuSbS2), Formamidinium tin triiodide (FASnI3), poly (3-hexylthiophene) P3HT to boost the output of conventional baseline CIGS solar cells structured. The device performance increases because of the minimized surface recombination velocity through heavily doped BSF layers, which increases the electric field at the rear contact. Among all proposed BSF layers CuAlO2 gives the best photoconversion efficiency (η) of 24.61 % followed by fill factor (FF) of 83.11 %, short circuit current density (JSC) of 35.87 mA/cm2, and open circuit voltage (VOC) of 0.82 V with quantum efficiency (QE) of ∼92 % for the whole visible range with the onset happening at ∼ 560 nm, thanks to the enhancement of carrier collection when BSF layer is incorporated. The novelty in this work is that for the first time with the CuAlO2 BSF layer, 24.61 % efficiency is reported at 1 μm CIGS layer thickness. We also examined how different BSFs affect the PV performance of the devices. The effect of temperature, the doping concentration of the BSFs, varying gallium proportion, JV & QE analysis, band diagram, and radiative recombination coefficient are varied to observe their impact on the PV parameters. This research introduces novel CIGS/CdS heterojunction configurations using various BSF layers to enhance efficiency, supporting the advancement of ultrathin, flexible, and tandem solar cell applications.

Mimicking somatic behavior of neurons using the integrate and fire model of 2D SnS memristive switching characteristics

This Letter presents the fabrication and characterization of a 2D SnS memristor, proposing its integrate and fire (I&F) model as a potential hardware implementation of neuronal somatic behavior. The memristor comprises a thin layer of tin (II) sulfide (SnS) sandwiched between copper (Cu) electrodes on a silicon (Si) substrate. This structure exhibits an impressive Roff:Ron ratio of 103 at a read voltage Vrd of 0.25 V with exceptionally low switching Vsw and set Vset voltages of 0.3 and 0.35 V, respectively, with ∼3 order variation between the maximum Rmax and Rmin resistances offered during single voltage sweep cycle. We have explained the memristive behavior using the dual ionic conduction mechanism in the SnS active layer. We extracted the real-time band diagram of SnS using ultraviolet photoelectron spectroscopy, explaining the low Vsw observed. We propose that the emulation of the I&F artificial neuron model exhibited by the fabricated device could serve as a promising application in the field of artificial neuron spiking.

Advancements in the photovoltaic optimization of a high performance perovskite solar cell based on graphene oxide (GO) hole transport layer

The increasing demand for efficient and sustainable green energy solutions has intensified the search for high-performance photovoltaic technologies. Herein, solar cell capacitance simulator (SCAPS-1D) is employed to simulate a novel solar cell design of the configuration, ITO/PC61BM/CH3NH3SnI3/GO/Fe. Various HTLs and electron transport layers (ETLs) are tested for comparison where graphene oxide (GO) HTL and PC61BM ETL exhibited exceptional electrical outcomes. The optimized PSC achieves a power conversion efficiency (PCE) of 36.27 % with Voc of 1.3462 V, Jsc of 34.84 mA/cm², and FF of 77.32 %. The built-in voltage (Vbi) of 0.31 V was derived from the band diagram at 300 K. Further exploration of the Mott-Schottky capacitance characteristics revealed that both donor and acceptor densities influence device performance. Notably, the Vbi remained stable at 0.32 V despite varying donor densities from 10¹⁰ cm⁻³ to 10¹⁹ cm⁻³, while increasing the acceptor density improved the Vbi from 0.2 to 0.72 V, suggesting remarkable operational performance at higher acceptor concentrations. This model device achieves maximum quantum efficiency of 100 % between 360 and 700 nm, therefore it exhibits a good photon capture for enhanced power conversion. Although the present study is based on numerical analysis, the findings inspire the promise of fabricating a physical solar cell of robust operational performance that can be injected into the production workflow for possible commercial scalability.

Methanol, ethylene glycol, and glycerol photoelectrochemical oxidation reactions on BiVO4: Zr,Mo/Pt thin films: A comparative study

The green H2 production plays a key role in the energy transition, however it still needs improvements to be applied in a large scale. The water oxidation reaction, as an anodic process to provide both protons and electrons for H2 production, possesses kinetic limitations. Therefore, the use of an alternative process like the oxidation of biomass-derivative species is extremely desired to replace water oxidation during H2 production. In this work, we provide a comparative study of different small organic molecules (methanol, ethylene glycol (EG), and glycerol) as alternatives to water oxidation at pristine BiVO4, Mo-Zr dopped BiVO4, and Pt co-catalyst BiVO4 photoanodes in neutral media. While the band energy diagram and surface morphology are similar for the distinct materials, the presence of Zr-Mo increases the charge carriers density. The presence of Pt acts as co-catalyst for the organic molecules. Regardless of the material employed, the activity order for each organic molecule reaction was: jwater< jmethanol < jEG < jglycerol affeered by both linear potential sweep and chronoamperometry at 1.23 V vs RHE. The presence of both Zr-Mo and Pt increases the photoactivity for the alcohol's oxidation, however the presence of Pt is more advantageous for glycerol oxidation than for other species, maintaining 80 % of activity after 24 h electrolysis. The reactivity of alcohols can be tentatively explained by the greater stability of radicals formed from larger molecules.

Photoinduced modulation and the effect of CNT loading on field effect transistor characteristics of CNT/ZnO/PVDF composite.

Carbon nanotube (CNT)/ZnO/ polyvinylidene fluoride (PVDF) polymer composite phototransistor is studied for the effect of CNT loading and the photoinduced modulation on its transfer characteristics. XRD study shows that the induced strain in the composite is due to the addition of CNT to the ZnO/PVDF composite. The percentage ofβ-phase present in PVDF is estimated through Raman spectroscopy and the composite's spectral response is determined by UV-Vis absorbance spectroscopy. From the DC electrical conductivity study it is found that the percolation threshold for the composites is obtained for 0.3 wt% of CNT, and 0.44 wt % of CNT loading makes the composite conductive. On adding 1 wt% of CNT, the electrical conductivity of the ZnO/PVDF composite increases 40 times (∼0.2μS m-1). The temperature-dependent DC conductivity shows that the conductivity of the composites changes from variable range hopping to band conductance upon an increase in CNT loading above the percolation threshold and exhibits a negative temperature coefficient. Two terminal photoconductivity studies are done to understand the photo enhancement and sensitivity of all the devices. PE hysteresis studies show that the polarization of the composites increases drastically from 0.05μC cm-2below the percolation threshold to 10-30μC cm-2above the percolation threshold of CNT in the composite. To study the effect of interfacial polarization on photoconductivity, the composite is studied in a three-terminal device format using SiO2as a gate dielectric. A band diagram analysis of the oxide-composite and CNT/ZnO interface is done to understand the mechanism behind the photoinduced field effect on transfer characteristics and the effect of CNT loading. The switching behavior and decay time under UV illumination are studied to understand the effect of CNT loading and photoinduced polarization. The persistent photoconductivity decreases and the charge collection efficiency of the FET increases as the CNT loading increases.

Spectroscopic Analysis of Electrical Phenomena and Oxygen Vacancy Generation for Self-Aligned Fully Solution-Processed Oxide Thin-Film Transistors.

This work unveils critical insights through spectroscopic analysis highlighting electrical phenomena and oxygen vacancy generation in self-aligned fully solution-processed oxide thin-film transistors (TFTs). Ar inductively coupled plasma treatment was conducted to fabricate an amorphous indium zinc oxide (a-InZnO) TFT in a self-aligned process. Results showed that the Ar plasma-activated a-InZnO regions became conductive, which means that a homogeneous layer can act as both channel and electrode in the device. Several techniques were employed to probe specific aspects of the source-drain-channel interface in the fully solution-processed TFTs. X-ray absorption near-edge structure and Extended X-ray absorption fine structure were conducted to investigate the existence of oxygen vacancies, which is the main driving factor in inducing a conductive region. X-ray photoelectron spectroscopy was also used to explain the oxygen refilling mechanism. Ultraviolet Photoelectron Spectroscopy was conducted to analyze the valence band maximum and work function. Integration of these results facilitated the construction of the energy band diagram at the interface, wherein a Schottky barrier height of ∼0.37 eV was observed. By leveraging these techniques, insights into the electronic properties and performance of next-generation transistors are gained, enabling their future widespread adoption.

Dual efficacy of potassium-doping in perovskite solar cells: Reducing hysteresis and boosting open-circuit voltage

The incorporation of potassium into perovskite solar cells (PSCs) has been empirically validated to mitigate hysteresis phenomena and boost the power conversion efficiency (PCE). However, the doping mechanism of potassium ions in the perovskite film and their effect on photocarrier recombination remains a topic of debate. Here, we grew doped MAPbI3: K single crystals by inverse temperature crystallization using KI as a dopant, and then perovskite thin films were spin-coated with dissolved MAPbI3: K crystals as a precursor. The doped MAPbI3: K perovskite films exhibit better crystal quality with large columnar grains and lower defect density. Employing Hall effect, ultraviolet photoelectron spectroscopy, and Kelvin probe force microscopy measurements, we definitively demonstrate that K-doping transforms the conductivity type of the perovskite film from a marginally N-type to a distinct P-type semiconductor. Furthermore, this doping strategy induces a concurrent downward shift in both the conduction band minimum and valence band maximum. As a result, the PCE of the PSCs increases from 15.15% to an impressive 20.66%, and the J–V curve hysteresis almost disappears. Additionally, theoretical simulations using SCAPS-1D software reveal a profound modification in the device's energy band diagram after K+-doping. Specifically, the energy level offset between the perovskite layer and the electron transport layer diminishes from 0.24 to 0.14 eV, with a result of bigger quasi-Fermi energy level splitting. This, in turn, elevates the open-circuit voltage (Voc) of the doped perovskite solar cell, underscoring the profound impact of potassium doping on enhancing PSC performance.

Band Diagram Insights into the Kinetic and Thermodynamic Engineering of Tandem Photocatalytic Cells.

In this work, we theoretically investigate the impact of kinetic and thermodynamic properties on the performance of photocatalytic cells operating in an unassisted tandem configuration, including electron affinity and ionization energies, recombination rates, and reaction rates. To this end, we present general rules and metrics for identifying and isolating the origin of an observed shift in the onset potential at either the photoanode or the photocathode of these devices. The correlation between kinetic and thermodynamic shifts in the onset potential is demonstrated through the use of band diagrams and key comparable features within readily accessible characterization tools: current-voltage plots are taken both under illumination and in the dark and further coupled with Mott-Schottky plots. To illustrate this conceptual framework, a model system comprised of a p-type doped BiVO4 photocathode and an n-type doped BiVO4 photoanode is employed. By varying each of the aforementioned kinetic and thermodynamic parameters in isolation, the manner in which these various mechanisms shift the onset potential is demonstrated. This work intends to showcase how kinetic and thermodynamic effects are distinctly manifested in these commonly used characterization tools and further proposes thermodynamic band-edge engineering as a potentially useful and largely unexplored avenue for possibly improving tandem cell performance, in addition to the conventional approach of optimizing kinetics.

Theoretical studies of the bipolar properties of ScAlN/AlGaN/GaN heterostructures for enhanced device applications

Abstract Here, we describe a systematic theoretical study of ScAlN/AlGaN/GaN heterostructures for enhanced high-electron-mobility transistors (HEMTs). We have investigated the carrier distributions and energy-band diagrams by solving the coupled Schrödinger and Poisson equations self-consistently. When the heterostructure is in the “off” state, the two-dimensional electron gas (2DEG) becomes increasingly depleted as the ScAlN thickness is increased to the critical thickness, at which point the two-dimensional hole gas (2DHG) appears. This critical thickness depends on the Sc content. Increasing the AlGaN thickness or Al content causes a simultaneous increase in the 2DEG and 2DHG sheet densities. In addition, when the HEMT is in the “on” state, 2DEG sheet density increases as ScAlN thickness increases, so long as the Sc content is less than 0.3; when the Sc content exceeds 0.4, this trend is reversed. For a given Sc content, double channels are produced when the ScAlN thickness exceeds the critical thickness.

Mechanism of frequency-dependent gate breakdown in p-GaN/AlGaN/GaN HEMTs

In this Letter, time-dependent gate breakdown (TDB) characteristics under dynamic switching conditions were investigated in p-GaN/AlGaN/GaN high-electron-mobility transistors (HEMTs) with either Schottky-type or Ohmic-type gates. The dynamic TDB of the Schottky-type devices increased with frequencies ranging from 100 Hz to 100 kHz, while that of the Ohmic-type devices remained frequency-independent. This was analyzed by the frequency-dependent electroluminescence (EL) characteristics on both types of devices with semi-transparent gate electrodes. The electroluminescence (EL) emission intensity of Schottky-type devices increased with elevated frequencies, notably for blue and ultraviolet emissions, which exhibited a pronounced positive correlation with frequency. In contrast, the EL emissions of Ohmic-type devices were frequency-independent. Energy band diagrams were drawn to explain the different TDB and EL behaviors between two types of devices. The frequency-enhanced EL emissions of the Schottky-type devices indicated the frequency-enhanced hole injection and radiative recombination, which then suppressed the hot-electron effects on the metal/p-GaN junction and enhanced the dynamic TDB in p-GaN/AlGaN/GaN HEMTs.

Electrical and UV-sensing performance of N-doped-Ba(Ti,Zr,Mo,Hf,Ta)O3-dielectric and ZnSnO-channel-based flexible thin-film transistors

Flexible thin-film transistors (TFTs) based on N-doped Ba(Ti,Zr,Mo,Hf,Ta)O3 dielectric and ZnSnO channel show high electrical and UV-sensing performance. The optimal N-doped Ba(Ti,Zr,Mo,Hf,Ta)O3 compositions with low equivalent oxide thicknesses (≈2 nm) and high-entropy (configurational entropy ≈ 1.59 R) are efficiently determined from a wide composition space (library). The film library is patterned to 450 metal–insulator-metal stacks, revealing dielectric constants ≈ 262–322 and loss (tan δ) ≈ 0.01–0.30 for the N-doped Ba(Ti,Zr,Mo,Hf,Ta)O3 at 1 kHz. The library is further integrated to 63 TFTs, and the promising ones exhibit the remarkable parameters: current on/off ratio of 108, threshold voltage (VT) of 0.02 V, saturation field-effect mobility of ≈76 cm2⋅V−1⋅s−1, and subthreshold swing of 0.062 V dec−1. The devices also exhibit desirable long-term stability for up to five months and perform reliably with small or negligible changes in VT and drain-source current under various gate-bias stress and temperature conditions. Furthermore, the TFT-based ultraviolet (253 nm) detector demonstrates impressive sensitivity (≈ 2 × 106) and responsibility (≈ 1171.9 A W−1). There is no substantial degradation in electrical or sensing characteristics under various levels of deformation. Charge transport in constructed energy band diagrams is used to elucidate the observed remarkable performance.

Dual-gate AlGaN channel HEMTs: advancements in E-mode performance with N-shaped graded composite barriers

Abstract This work evaluates the performance of dual gate AlGaN channel HEMTs on SiC substrate. The study analyzes two HEMT structures that differ only in barrier design, one design consists of fixed composite barriers (FCB-HEMT) i.e. there is fixed Aluminum composition x = 0.48 in the first Al x Ga1−x N barrier and x = 0.42 in the second Al x Ga1−xN barrier while the other design comprises N-shaped graded composite barriers (NGCB-HEMT) i.e. the Aluminum content varies gradually from 0.4 to 0.48 in the first AlGaN barrier and from 0.34 to 0.42 in the second AlGaN barrier. The paper concentrates on energy band diagrams, electron concentration profile, electric field distribution, drain and transfer characteristics, and the effects of high temperature on drain characteristics and mobility of the NGCB-HEMT. It has been reported that at zero gate bias, the FCB-HEMT has a drain current density of 0.137 A mm−1 while it decreases to 0.0058 A mm−1 in the case of NGCB-HEMT, thus presenting a novel approach towards enhancement-mode AlGaN HEMTs. Hence, grading can be optimized in the composite barriers to achieve enhancement mode operation of AlGaN channel HEMTs. Furthermore, the study reveals that the critical electric field of FCB-HEMT is 6.9975 M V cm−1, while that of NGCB-HEMT is 5.3124 M V cm−1, demonstrating their usefulness in electronic devices that operate at high voltages and harsh temperatures. Moreover, at higher temperatures, the phenomenon of optical phonon scattering leads to decreased mobilities, which in turn causes low drain currents relative to the drain voltage.

Photocatalysis of Adsorbed Catechol on Degussa P25 TiO2 at the Air-Solid Interface.

Semiconductor photocatalysis with commercial TiO2 (Degussa P25) has shown significant potential in water treatment of organic pollutants. However, the photoinduced reactions of adsorbed catechol, a phenolic air pollutant from biomass burning and combustion emissions, at the air-solid interface of TiO2 remain unexplored. Herein we examine the photocatalytic decay of catechol in the presence of water vapor, which acts as an electron acceptor. Experiments under variable cut-off wavelengths of irradiation (λcut-off ≥ 320, 400, and 515 nm) distinguish the mechanistic contribution of a ligand-to-metal charge-transfer (LMCT) complex of surface chemisorbed catechol on TiO2. The LMCT complex injects electrons into the conduction band of TiO2 from the highest occupied molecular orbital of catechol by visible light (≥2.11 eV) excitation. The deconvolution of diffuse reflectance UV-visible spectral bands from LMCT complexes of TiO2 with catechol, o-semiquinone radical, and quinone and the quantification of the evolving gaseous products follow a consecutive kinetic model. CO2(g) and CO(g) final oxidation products are monitored by gas chromatography and Fourier-transform infrared spectroscopy. The apparent quantum efficiency at variable λcut-off are determined for reactant loss (Φ- TiO2/catechol = 0.79 ± 0.19) and product growth ΦCO2 = 0.76 ± 0.08). Spectroscopic and electrochemical measurements reveal the energy band diagram for the LMCT of TiO2/catechol. Two photocatalytic mechanisms are analyzed based on chemical transformations and environmental relevance.

Emerging class of SrZrS3 chalcogenide perovskite solar cells: Conductive MOFs as HTLs - A game changer?

The emerging SrZrS3 chalcogenide perovskite has been suggested as a potential alternative to lead halide perovskites, offering unique optoelectronic properties while addressing concerns such as lead toxicity and instability. Our research explored its potential, demonstrating the use of conductive metal-organic frameworks (c-MOFs) Cu-MOF ({[Cu2(6-mercapto nicotinate)]·NH4}n), NTU-9, Fe2(DSBDC), Sr-MOF ({[Sr(ntca)(H2O)2]·H2O}n), Mn2(DSBDC), and Cu3(HHTP)2 as promising substitutes for traditional HTLs via SCAPS-1D. By systematically optimizing the absorber and HTL properties, maximum PCEs of 30.60 %, 29.78 %, 28.29 %, 28.44 %, 28.80 %, and 28.62 % were accomplished for solar cell devices based on the aforementioned MOFs, respectively. Comparative analysis of initial and optimized solar cells using energy band diagrams, Nyquist plots, and quantum efficiency revealed that optimized devices consistently raised quasi-Fermi levels, significantly enhanced conductivity, and boosted solar cell performance. Additionally, the high recombination resistance of 1.4 × 107 Ω cm2, improved spectral response of 35 % in the NIR region, and heightened built-in potential (∼0.99 V) resulted in the highest efficiency of 30.60 % for Cu-MOF solar cells. This research highlights the promising potential of novel SrZrS3 absorbers and the utilization of c-MOFs as HTLs in solar cells, positioning them as a game changer in the PV field.

Performance enhancement of MOCVD grown Zn-doped β-Ga2O3 Deep-Ultraviolet photodetectors on silicon substrates via TiN buffer layers

Integrating β-Ga2O3-based devices on silicon substrates faces challenges due to lattice and thermal expansion mismatches, leading to performance-degrading defects. Therefore, this work explores the utilization of a titanium nitride (TiN) buffer layer in order to enhance the performance of MOCVD grown Zn-doped β-Ga2O3-based deep-ultraviolet (DUV) photodetectors (PDs) on silicon substrates with 12, 24, and 36 sccm diethylzinc (DEZn) flow rates. The XPS depth profiles revealed the presence of TiN buffer layer in β-Ga2O3/TiN/Si films, which served as a diffusion barrier during deposition, preserving interface integrity and reducing defect density. Zn-doped β-Ga2O3/TiN/Si based DUV PDs revealed remarkable results. The 12 sccm Zn-doped β-Ga2O3/TiN/Si PDs demonstrated an exceptional maximum responsivity of 31.4 A/W, which is 7 times higher compared to the undoped β-Ga2O3/TiN/Si (4.47 A/W) under a 5 V bias and 240 nm wavelength illumination. This PD exhibited the detectivity of 1.68 × 1013 Jones and EQE of 1.63 × 104 %. This PD possess quick rise time of 6.5 s and fall time of 0.5 s. The energy band diagram for Zn-doped β-Ga2O3/TiN/Si metal–semiconductor-metal type PDs is discussed. This work demonstrates that TiN buffer layers and Zn doping significantly improve the performance and reliability of β-Ga2O3-based DUV photodetectors on silicon substrates.

Electronic Barriers Behavioral Analysis of a Schottky Diode Structure Featuring Two-Dimensional MoS2

This research presents a comprehensive study of a Schottky diode fabricated using a gold wafer and a bilayer molybdenum disulfide (MoS2) film. Through detailed simulations, we investigated the electric field distribution, potential profile, carrier concentration, and current–voltage characteristics of the device. Our findings confirm the successful formation of a Schottky barrier at the Au/MoS2 interface, characterized by a distinct nonlinear I–V relationship. Comparative analysis revealed that the Au/MoS2 diode significantly outperforms a traditional W/Si structure in terms of rectification performance. The Au/MoS2 diode exhibited a current density of 1.84 × 10−9 A/cm2, substantially lower than the 3.62 × 10−5 A/cm2 in the W/Si diode. Furthermore, the simulated I–V curves of the Au/MoS2 diode closely resembled the ideal diode curve, with a Pearson correlation coefficient of approximately 0.9991, indicating an ideality factor near 1. A key factor contributing to the superior rectification performance of the Au/MoS2 diode is its higher Schottky barrier height of 0.9 eV compared to the 0.67 eV of W/Si. This increased barrier height is evident in the band diagram analysis, which further elucidates the underlying physics of Schottky barrier formation in the Au/MoS2 junction. This research provides insights into the electronic properties of Schottky contacts based on two-dimensional MoS2, particularly the relationship between electronic barriers, system dimensions, and current flow. The demonstration of high-ideality-factor Au/MoS2 diodes contributes to the design and optimization of future electronic and optoelectronic devices based on 2D materials. These findings have implications for advancements in semiconductor technology, potentially enabling the development of smaller, more efficient, and flexible devices.