Search

The band offset (BO) at semiconductor heterojunctions and the Schottky barrier height (SBH) at metal–semiconductor interfaces are important device parameters that are directly related to the charge distribution at the interface. Recently, an approach based on the neutral polyhedra theory (NPT) was developed that allowed interface charge density to be modeled and the BO/SBH at epitaxial interfaces to be quantitatively explained and predicted. The present work shows that the band alignment conditions for a large number of practical interfaces, the majority of which are polycrystalline, can also be explained by modeling the charge distribution at the interface with densities of bulk crystals. Two types of interfaces are distinguished: those between crystals with similar chemical bonds and those with dissimilar bonds. The majority of interfaces presently studied belong to the first category, with their experimentally measured BO/SBHs in good agreement with the structure-independent predictions from NPT. The similarity of bonds at the interface and in bulk crystals makes it unnecessary to make adjustments for the interface bonds and is argued to be the reason behind "bulk-like" behavior in band alignment conditions at such interfaces. The effect of interface bonds that cannot be ignored at some interfaces with perovskite oxides is successfully treated by model solids constructed with the atoms-in-molecules theory. The validity and the wide applicability of density-based theories in the explanation and prediction of band alignment at solid interfaces are demonstrated. [ABSTRACT FROM AUTHOR]

Large Schottky barriers formed at the interfaces between graphene and 2D semiconductors often degrade device performance. Here, taking the Janus MoSO as a prototype and using the first-principles calculations together with the band unfolding technique, we demonstrate that the Ohmic contact (OC), which is absent in pristine graphene/MoXY (X/Y = S, Se, Te. X ≠ Y), is realized in the pristine graphene/MoSO (G/MoSO) heterostructure. G/OMoS shows the n -type OC (OC- n) that leads to the p -doping of the graphene layer with a hole density of 1.17 × 10 13 /cm 2 , while G/SMoO exhibits the p -type Schottky contact with a tunable Schottky barrier height. The realization of OC and the interface dependent contact type are mainly attributed to the large intrinsic dipole between asymmetric S and O layers, which dominate the different behaviors of charge transfer and the associated interface dipole in heterostructures. Inspired by the finding, considering the larger dipole moment in Janus MoSeO and MoTeO, we further confirm that both OC- n and OC- p exist in pristine G/MoSeO and G/MoTeO. Moreover, on comparison with MoSO, both G/OMoS and G/SMoO show enhanced optical absorptions (∼ 10 5 cm − 1 ) in most of the visible light range. Our results not only show the potential application of G/MoSO in nanoelectronic devices such as field-effect transistors but also indicate that dipole engineering would help us to predict or design desirable electric contacts of Janus-transition metal dichalcogenide-based metal/semiconductor systems in advance. [ABSTRACT FROM AUTHOR]

Owing to their unique optical and electronic properties, vertical van der Waals heterostructures (vdWHs) have attracted considerable attention in optoelectronic applications, such as photodetection, light harvesting, and light-emitting diodes. To fully harness these properties, it is crucial to understand the interfacial charge transfer (CT) and recombination dynamics across vdWHs. However, the effects of interfacial energetics and defect states on interfacial CT and recombination processes in graphene-transition metal dichalcogenide (Gr-TMD) vdWHs remain debated. Here, we investigate the interfacial CT dynamics in Gr-TMD vdWHs with different chemical compositions (W, Mo, S, and Se) and tunable interfacial energetics. We demonstrate, using ultrafast terahertz spectroscopy, that while the photo-induced electron transfer direction is universal with graphene donating electrons to TMDs, its efficiency is chalcogen-dependent: the CT efficiency of S atom-based vdWHs is 3–5 times higher than that of Se-based vdWHs thanks to the lower Schottky barrier present in S-based vdWHs. In contrast, the electron back transfer process from TMD to Gr, which defines the charge separation time, is transition metal-dependent and dominated by the mid-gap defect level of TMDs: W transition metal-based vdWHs possess extremely long charge separation, well beyond 1 ns, which is significantly longer than Mo-based vdWHs with only 10 s of ps charge separation. This difference can be traced to the much deeper mid-gap defect reported in W-based TMDs compared to Mo-based ones, resulting in modified energetics for the back electron transfer from the trapped states to graphene. Our results shed light on the role of interfacial energetics and defects by tailoring chemical compositions of TMDs on the interfacial CT and recombination dynamics in Gr-TMD vdWHs, which is pivotal for optimizing optoelectronic devices, particularly in the field of photodetection. [ABSTRACT FROM AUTHOR]

The S vacancy at metal/ MoS 2 interface plays a much important role than the semiconductor itself. In this work, the influence of different configurations of S vacancy concentrations on the effective work function and band structure of the Au/ MoS 2 interface has been investigated systematically using first-principles calculations. The study specifically explores the effective work function of the Au/ MoS 2 interface, the deviation of interface effects from the vacuum work function, and the dipole moment caused by interface charge transfer. The results reveal that the electronic work function of Au/ MoS 2 increases with the increase in S vacancy concentration, but the rate of increase tends to slow down with higher S concentrations. The variation in the effective work function of the Au/ MoS 2 interface may be attributed to the presence of S vacancies and the exposure of Mo atoms. S vacancies lead to a reduction in the Schottky barrier, resulting in increased leakage current. The Fermi pinning caused by S vacancy concentration and location is also observed. The results obtained in this study can serve as a theoretical foundation for applications in electronic devices that rely on metal/ MoS 2 contact. [ABSTRACT FROM AUTHOR]

In this paper, the p-GaN gate AlGaN/GaN high electron mobility transistors (HEMTs) with varying combinations of gate metal work function and gate geometry are fabricated and investigate the influence of gate leakage current (IGS) on the threshold voltage (VTH) and subthreshold swing (SS). The unique dependence of VTH and SS on gate geometry for different metals is observed, which is different from traditional field-effect transistors. A novel hybrid physics model, consisting of the traditional capacitance divider model and hole injection model, is proposed to explain this phenomenon, and the results exhibit an excellent agreement with the experimental data. The holes traverse the gate/p-GaN Schottky barrier by thermal emission or tunneling and inject into the p-GaN layer, generating the IGS. Expanding upon the traditional capacitance divider model, a portion of the injected holes accumulate at the p-GaN/AlGaN interface and induce the corresponding electrons at the AlGaN/GaN heterojunction, which promotes channel conduction. Hence, the transfer curves display the correlation between IGS and VTH as well as SS. The results show that high IGS can alleviate the instability of VTH caused by the lithographic overlay error, and simultaneously optimize SS. This work offers a novel perspective for examining the turn-on mechanism of p-GaN HEMTs, thereby contributing to device design. [ABSTRACT FROM AUTHOR]

We report on the study of electron transport and band offset across β -Ga 2 O 3 /4H-SiC N–n isotype heterojunction. N-type β -Ga 2 O 3 of thickness 2.7 μ m was grown using low-pressure chemical vapor deposition using germanium (Ge) as the dopant on an n-type 4H-SiC substrate. The grown epilayer having (− 201) orientation was verified through XRD. Temperature-dependent I–V and C–V measurements were performed (50–300 K) to investigate the transport properties across the heterojunction. First, lateral diodes were fabricated on β -Ga 2 O 3 , and from C–V, n-doping was estimated to be 2.3 × 10 17 cm − 3 in the epilayer while the Schottky barrier height was estimated to be 1.75 eV. In top-down I–V sweeps, the reverse current across the heterojunction exhibited marginal dependence on temperature, indicating a possible tunnelling-based transport mechanism, while the forward current exhibited an exponential dependence on both temperature and the applied bias. The band diagram indicated the formation of a two-dimensional electron gas (2DEG) at the hetero-interface, which was indirectly confirmed using C–V measurement and TCAD simulation at low temperatures. From the position of the Fermi level in SiC and band diagram, a conduction band offset of 0.4–0.5 eV was estimated between β -Ga 2 O 3 and 4H-SiC. [ABSTRACT FROM AUTHOR]

Pt/GaN Schottky barrier diodes and GaN epitaxial layers on sapphire substrates were studied under swift heavy ion irradiation using 100 MeV O7+ ions having fluences in the range of 1 × 1010–6.4 × 1013 ions/cm2. It was observed that ideality factor, Schottky barrier height, and series resistance increased, while carrier concentration decreased with increasing ion fluence. The ex situ measurements, such as x-ray diffraction and UV–Vis spectroscopy, revealed that GaN layers exhibit negligible variation in structural and bandgap characteristics after irradiation with oxygen ions. The cross-sectional transmission electron microscopy images of the GaN epitaxial layer irradiated at 5 × 1012 ions/cm2 confirmed the absence of irradiation-induced tracks or defect clusters, indicating only point defects that can act as charge traps without structural damage. [ABSTRACT FROM AUTHOR]

Photodetection technology has garnered extensive research attention due to its wide‐ranging applications in fields such as infrared (IR) imaging, environmental monitoring, and optical communication. Dirac semimetals, characterized by high carrier mobility, zero bandgap, and broad spectral response, show great promise in the development of high‐performance photodetectors. The combination of Dirac semimetals and semiconductors in heterostructures enables broadband photodetection from ultraviolet (UV) to long‐wave infrared (LWIR), offering a new approach to extending the wavelength range of photodetection. This review explores 2D Dirac semimetal/semiconductor heterojunction photodetectors (DSSHP), beginning with an overview of the unique properties of Dirac semimetals. It then discusses various photoresponse mechanisms across different wavelength ranges. Additionally, strategies for enhancing photodetector performance are reviewed and analyzed based on their underlying principles. Finally, the key challenges for Dirac semimetal photodetectors are summarized, and potential future developments are outlined. [ABSTRACT FROM AUTHOR]

ZnO varistor samples generally have poor preparation repeatability. In this work, ZnO varistor samples A and B with the same preparation technique showed significant differences in properties, and the reasons were explored in detail. Nonlinear coefficient (α) values of 42.59 and 72.68, and leakage current density of 0.013 mA/cm2 and 0.002 mA/cm2 were found for samples A and B, respectively, which are markedly different between the samples. However, samples A and B showed the same phases. In addition, samples A and B exhibited mean grain size (d) of 2.21 μm and 2.47 μm, double Schottky barrier height (φB) of 0.45 eV and 0.48 eV, and grain boundary resistivity (ρgb) of 5.32 × 106 Ω m and 5.40 × 106 Ω m, respectively, which were all similar between the two samples. According to the low-temperature dielectric spectral analyses, the values of k1 of samples A and B, reflecting the concentration of interstitial zinc, were 14.06 and 11.09, and the values of k2 reflecting the concentration of oxygen vacancy were 7.48 and 3.35, respectively. Therefore, the obvious difference in the electrical properties between samples A and B may be caused mainly by the obvious difference in the concentration of oxygen vacancy. Thus, this work provides evidence of the effects of oxygen vacancy on the electrical properties of ZnO varistors. [ABSTRACT FROM AUTHOR]

In this work, metal contacts are fabricated on a p-type Hg1−xCdxTe semiconductor, with composition x = 0.30 and acceptor mercury vacancy concentration in the range of 1016 cm−3, by two different technological processes. Depending on the fabrication process, either non-ohmic contacts, with highly nonlinear current–voltage I(V) characteristics, or ohmic contacts are obtained. Different test patterns are measured at variable temperatures down to 77 K. Isolated small-area contacts, comparable to those in focal plane arrays (FPAs), are used to characterize the metal/semiconductor Schottky barrier energy, while transfer length method (TLM) structures are used to estimate the contact specific resistivity of the ohmic contacts. Classical circular TLM (CTLM) patterns are studied and, in addition, new patterns, referred to as variable-width closed TLM (VW-CTLM), are proposed. The linear I(V) characteristics, measured at variable temperatures down to 77 K, demonstrate that high-performance true ohmic contacts on p-type Hg1−xCdxTe can be obtained. To our knowledge, the contact specific resistivity values for these contacts, in the range 0.7–1.8 × 10−4 ohms cm2 at 77 K, are lower than the published state-of-the-art values. The very stable values of contact resistance over the whole temperature range is coherent with a dominant pure tunnel conduction mechanism through the metal/Hg1−xCdxTe barrier. TLM is used to analyze the ohmic contacts, and in some cases is used to obtain useful information even on some of the non-ohmic contacts, which is somewhat unusual and possibly innovative. [ABSTRACT FROM AUTHOR]

Silicon germanium presents a great opportunity to improve the performance of Schottky barrier transistors through band gap engineering. This work presents a multi‐gated reconfigurable transistor built from pure SiGe channel material for bandgap reduction. The device utilizes industrial‐grade SiGe‐on‐insulator wafers, a hysteresis‐free HfO2‐based dielectric, and alloyed NiTiGeSi contacts, leading to Fermi‐level pinning of the Schottky contact about 200 meV above the valance band. Electron and hole transport in this complex structure have been analyzed as a function of the applied back‐bias by electrical measurements and corresponding technology computer‐aided design simulation. An on/off ratio of 103 with on‐currents up to 3.15 µA can be achieved for the p‐mode. At the same bias, the n‐mode showed no influence of the top gates due to a dominant parasitic hole current path. A strong positive back‐bias induced an n‐type switching operation, resulting in similar on/off‐ratio and subthreshold slopes as achieved with the p‐type mode. Opposed to this, it is shown that a strong negative back‐bias leads to a loss of gate control over the p‐mode, inducing an always‐on behavior. The results will give guidelines for applying Schottky barrier devices in industrial SiGe technologies, e.g., for reconfigurable or cryogenic computing. [ABSTRACT FROM AUTHOR]

The impact of tin (Sn4+) doping on sodium yttrium copper titanate (Na 0.5 Y 0.5 Cu 3 Ti 4 O 12) ceramics, prepared using a conventional mixed-oxide route, was thoroughly investigated in terms of microstructure, dielectric properties, electrical response, non-linear behaviors, and humidity-sensing characteristics. All sintered ceramics showed a dense micro-structure and a pure Na 0.5 Y 0.5 Cu 3 Ti 4 O 12 phase without any secondary phases. The doped Na 0.5 Y 0.5 Cu 3 Ti 4−x Sn x O 12 ceramics, with x = 0.05, demonstrated excellent dielectric properties, including a low dielectric loss tangent (∼0.032) and a giant dielectric permittivity (∼1.8 × 104) across a wide temperature range. Sn4+ doping improved the non-linear behaviors at 25 °C in Na 0.5 Y 0.5 Cu 3 Ti 4 O 12 , with a reduced dielectric loss tangent corresponding to an enhanced grain boundary (GB) response. The colossal dielectric response is attributed to the internal barrier layer capacitor model, which relates to the Schottky barrier height (Φ B) at the GBs. Notably, the Φ B values for the Na 0.5 Y 0.5 Cu 3 Ti 4 O 12 ceramic increased with Sn4+ ion doping. Additionally, an in-depth study of the humidity-sensing properties of the Sn4+-doped Na 0.5 Y 0.5 Cu 3 Ti 4 O 12 material revealed that the capacitance at 1 kHz increased with increasing relative humidity levels, from 30 % to 90 %, suggesting potential applications in humidity-sensing technologies. [ABSTRACT FROM AUTHOR]

We report on the electrical characteristics of field-effect transistors (FETs) and Schottky diodes based on In2Te3 grown on hexagonal boron nitride (h-BN) substrates utilizing molecular beam epitaxy (MBE). A two-step growth method was used to increase surface coverage and large grain sizes for high-quality In2Te3. Scanning transmission electron microscopy (STEM) imaging revealed an atomically clean and abrupt interface between the In2Te3 and h-BN substrates. Compared with the previously reported In2Te3 FETs, the MBE-grown In2Te3 FETs exhibited superior electrical properties, including a mobility of 6.07 cm2 V−1 s−1, a subthreshold swing close to 6 V dec−1, and an impressive on/off ratio of approximately 105. Furthermore, the Ti/In2Te3 Schottky diodes exhibit a low saturation current of 0.4 nA, an ideality factor of 26.7, and a Schottky barrier height of 0.68 eV. We report on the fabrication and electrical characteristics of In2Te3 thin films grown on h-BN using molecular beam epitaxy(MBE). Cross-sectional scanning transmission electron microscopy images showed an atomically clean and abrupt interface between In2Te3 and h-BN substrates. The MBE-grown In2Te3 electronic devices exhibited superior electrical properties compared to previously reported In2Te3 field effect transistors(FETs) and In2Te3-based Schottky diodes. [ABSTRACT FROM AUTHOR]

Ensuring high‐quality surface passivation is the key to realizing high‐performance self‐powered optoelectronic devices, as it significantly impacts carrier transport. 2D hexagonal boron nitride (hBN) exhibits exceptional material characteristics, including a wide bandgap, high dielectric constant, minimized dangling bonds, and high chemical stability, making it one of the most promising candidates for high‐quality passivation. Nevertheless, the passivation characteristics of hBN on Ge and their influence on self‐powered photodetection remain unexplored, as well as their effects on carrier recombination lifetime, interface defect density, and Schottky barrier height. In this study, the first demonstration of enhanced Schottky junction photodiode characteristics and the impact of the surface passivation on carrier lifetime and defect density using an hBN monolayer on Ge are presented. The characteristics of hBN/Ge with Al2O3/Ge are compared to demonstrate the superior passivation quality of hBN over conventional materials. These results highlight the significant potential of hBN as an effective passivation for optoelectronic device applications. [ABSTRACT FROM AUTHOR]

Herein, an ultralow‐threshold voltage‐responsive synaptic memristor based on CuxO and B‐doped diamond (BDD) heterojunctions is developed. The aggregation of oxygen vacancies corresponding to the high‐ and low‐resistance states forms the foundation for the hysteresis behavior. The I–V curves exhibit impressive analog resistive switching (analog RS), which renders the memristor highly suitable for simulating synaptic stimulation. The reliable stability of this structure is confirmed using 122 individual devices, achieving a yield of 90.2% with highly consistent I–V curves. In addition, the effect of the B‐dopant level in the diamond is investigated. By reducing the B/C ratio of the precursor from 1:500 to 1:2000 during the hot filament chemical vapor deposition synthesis process, a significant 55.3% reduction in current is achieved, leading to lower energy consumption. The Schottky barrier height increases with decreasing B‐dopant levels, providing a broader adjustable range for synaptic weight renewal. Remarkably, when the pulse amplitude is decreased to an ultralow value of 3 mV, the synaptic function of the device remains observable, with an energy consumption of only 9.5 × 10−11 J. To the best of the authors’ knowledge, this is the first report of such a low‐amplitude pulse voltage in a two‐terminal memristor. [ABSTRACT FROM AUTHOR]

The NiFeP/g-C 3 N 4 catalyst synthesized in this study exhibits excellent OER activity and stability with its unique spherical cluster heterostructure. The Schottky contact between NiFeP and g-C 3 N 4 effectively reduces the charge transfer resistance (R ct), significantly improving the overall charge transfer capability. [Display omitted] The construction of heterojunctions can reduce the energy barrier for the oxygen evolution reaction (OER), which is crucial for the design of efficient electrocatalysts. A novel OER electrocatalyst, composed of g-C 3 N 4 -supported NiFeP spherical nanoclusters, was successfully synthesized using a simple hydrothermal method and a gas-phase precipitation method. Benefiting from its unique spherical nanocluster structure and strong electronic interactions among Ni, Fe, and P, the catalyst exhibited outstanding performance under alkaline conditions, with an overpotential of only 232 mV at a current density of 10 mA cm−2 and a Tafel slope of 103 mV dec-1. Additionally, the electrical resistance of NiFeP/g-C 3 N 4 (R ct = 5.1 Ω) was much lower than that of NiFeP (R ct = 10.8 Ω) and layered g-C 3 N 4 (R ct = 44.8 Ω). The formation of a Schottky barrier heterojunction efficiently reduced electron transfer impedance during the OER process, accelerating the electron transfer from g-C 3 N 4 to NiFeP, enhancing the carrier concentration, and thereby improving the OER activity. Moreover, The robust g-C 3 N 4 chain-mail protects NiFeP from adverse reaction environments, maintaining a balance between catalytic activity and stability. Furthermore, ab initio molecular dynamics (AIMD) and density functional theory (DFT) were conducted to explore the thermal stability and internal electron transfer behavior of the cluster heterojunction structure. This study offers a broader design strategy for the development of transition metal phosphide (TMPs) materials in the oxygen evolution reaction. [ABSTRACT FROM AUTHOR]

Atomic chalcogen vacancy is the most commonly observed defect category in two dimensional (2D) transition‐metal dichalcogenides, which can be detrimental to the intrinsic properties and device performance. Here a low‐defect density, high‐uniform, wafer‐scale single crystal epitaxial technology by in situ oxygen‐incorporated "growth‐repair" strategy is reported. For the first time, the oxygen‐repairing efficiency on MoS2 monolayers at atomic scale is quantitatively evaluated. The sulfur defect density is greatly reduced from (2.71 ± 0.65) × 1013 down to (4.28 ± 0.27) × 1012 cm−2, which is one order of magnitude lower than reported as‐grown MoS2. Such prominent defect deduction is owing to the kinetically more favorable configuration of oxygen substitution and an increase in sulfur vacancy formation energy around oxygen‐incorporated sites by the first‐principle calculations. Furthermore, the sulfur vacancies induced donor defect states is largely eliminated confirmed by quenched defect‐related emission. The devices exhibit improved carrier mobility by more than three times up to 65.2 cm2 V−1 s−1 and lower Schottky barrier height reduced by half (less than 20 meV), originating from the suppressed Fermi‐level pinning effect from disorder‐induced gap state. The work provides an effective route toward engineering the intrinsic defect density and electronic states through modulating synthesis kinetics of 2D materials. [ABSTRACT FROM AUTHOR]

This study investigates the sensitivity of Underlap Gate Cavity-based Reconfigurable Silicon Nanowire Schottky Barrier Transistor (UCG-RSiNW SBT) with an underlap gate-drain region for biosensing application. The featured unique reconfigurable capability enables the device to operate as either p-type or n-type, dependent on the applied bias polarity. The proposed biosensor incorporates a cavity beneath the control gate on the source side, facilitating the placement of both neutral and charged biomolecules with varying dielectric constant (K) values. Upon injection of biomolecules into the cavity, the device changes electrostatic characteristics, including modulation in threshold voltage, potential, electric field, and sub-threshold swing, I ON , I ON / I OFF ratio. The threshold voltage ( V TH ) Sensitivity of n-mode is enhanced by 97.91 % , while that of p-mode is raised by 16 % compared to conventional RFET biosensors. The drain current sensitivity and the linearity of proposed biosensor is enhanced upto the values of 2792 and 0.997 respectively in n-mode configuration whereas in p-mode configuration, the drain current sensitivity and the linearity comes out to be 968 and 0.995 respectively. These high sensitivity and linearity values make this biosensor superior to the existing state-of-the-art biosensors. The findings from this study provide valuable insights into the development of highly sensitive biosensors for applications in diverse fields, including healthcare and biotechnology. [ABSTRACT FROM AUTHOR]

This work investigates the performance of state-of-the-art non-commercial 6.5 kV Silicon Carbide (SiC) PiN and Junction Barrier Schottky (JBS) diodes in hybrid (Si IGBT with SiC diode) and full SiC (SiC MOSFET with SiC diode) switch topologies. The static and dynamic performance has been systematically evaluated at distinct temperatures, gate resistances and currents for each configuration. The SiC PiN diode presented higher current density capability and lower leakage current density than the JBS diode. Moreover, in most cases, the SiC PiN diode-based topologies demonstrated slightly higher total switching losses compared to the SiC JBS diode-based equivalent configurations. A loadability analysis in a three-level NPC converter is presented to evaluate the potential of each configuration in a converter application. The SiC PiN technology presented a 25% power extension compared to the SiC JBS technology with similar efficiency at typical industrial drives switching frequency operation when comparing same-active-area diode technologies. Finally, a long-term reliability test (H3TRB) is presented to demonstrate the SiC PiN diode technology's potential for operation in harsh environments. Such characteristics show the advantage of the 6.5 kV SiC PiN diode when a high current density (>100 A/cm2), high efficiency and reliability are required. [ABSTRACT FROM AUTHOR]

The wide bandgap oxide semiconductor thin films are synthesized using tetrahydroxogallate (III) ammonium {NH4Ga(OH)4} precursor at a concentration of 10 at% Ga and varying amounts of hydrated aluminum nitrate between 0.6 and 3.2 at%. Thin films of β‐Ga2O3:Al are synthesized by spin coating and spray pyrolysis with postannealing in nitrogen ambient at 930 °C. The structural properties of the thin films are investigated using XRD and Raman spectroscopy, while the electrical characteristics are determined using 4‐point probe, current–voltage (I–V), and capacitance–voltage (C–V) measurements with Ti/Al/Ni/Au Ohmic contacts and Pd/Au Schottky contacts. The β‐Ga2O3 with 2.2 at% Al is found to be the optimal concentration in this study, resulting in ideality factors of 1.10 and 1.09, saturation currents of 3.17 × 10−6 and 3.10 × 10−6 A, Schottky barrier heights of 0.73 and 0.88 eV, and series resistances of 948 and 955 Ω, for the spin‐coated and pyrolytically sprayed samples respectively. [ABSTRACT FROM AUTHOR]

Recently, CdSe has become a prospective material for photocatalytic hydrogen evolution. However, the photocatalytic activity of pure CdSe is still dissatisfactory due to the electron-hole pair complex and lack of active sites. In this study, CdSe/NiS Schottky heterojunction photocatalysts was successfully prepared by the hydrothermal method. Of these, CdSe is daisy-like and NiS is hydrangea-like. The photocatalytic hydrogen evolution results indicated that the photocatalytic hydrogen production rate of 25NiS/CdSe was 9399 μmol g−1 h−1 under visible light irradiation in the presence of sacrificial agents, which was 120 times higher than that of pure CdSe (78 μmol g−1 h−1). Using X-ray photoelectron spectroscopy, the catalyst's elemental makeup was revealed. Photoluminescence spectroscopy and electrochemical characterizations demonstrated that the carrier separation efficiency of NiS/CdSe was significantly improved compared with CdSe and the overpotential was lowered. This improvement can be attributed to the formation of Schottky barriers. In addition, the metal-like nature of NiS promoted charge transfer and provided additional reactive active sites for the system. This study offers novel insights for the further design of low-cost, visible-light-driven photocatalysts with high photocatalytic activity. [Display omitted] • A new and efficient CdSe/NiS photocatalyst was successfully synthesized. • NiS provides active sites for hydrogen production. • The metal-like properties of NiS and Schottky heterojunctions work together to promote charge transfer. • The hydrogen production of the optimized heterojunction is 120 times that of pure CdSe. • The optimized heterojunction exhibits the hydrogen production rate of 9399 μmol g−1 h−1. [ABSTRACT FROM AUTHOR]

Highly accelerated lifetime test (HALT) for lifetime evaluation was performed on the state-of-art automotive MLCC prototypes by varying Dy/Mg (donor/acceptor) ratio added to BaTiO 3. The results clearly showed that the mean time to failure (MTTF) more than 280 times as the Dy/Mg ratio increased from 1.0 to 10.0. Since oxygen vacancies typically form in-gap state/defect at the donor level, the activation energy value under thermal activation process as a function of voltage was calculated and compared by non-destructive testing (I – V curve) for an accurate evaluation of the extrinsic behavior. It was found that barrier height at the Ni/BT interface decreases as the voltage increases, resulting in a decrease in activation energy. As the Dy/Mg ratio increases, the density of defects/in-gap states formed at the donor level in the bandgap by oxygen vacancies decreases, which may lead to a decrease in the number of electrons excited by the external voltage. Furthermore, it was verified that the calculated Schottky barrier height of the 10.0 Dy/Mg ratio under voltage has higher value than that of the 2.6 Dy/Mg ratio. Based on the results of this study, we propose a new indicator for the design of automotive MLCCs with high lifetime reliability that can be used for comparative analysis of additive compositions through non-destructive test (I – V curve) with low evaluation time/cost. [Display omitted] [ABSTRACT FROM AUTHOR]

This study undertakes a comparative analysis of Schottky diodes using three prominent SiC polytypes (3C, 4H, and 6H). The comparison involves meticulous calculations of the Schottky barrier resulting from the metal/SiC interface for each polytype assessed in both practical and theoretical scenarios. Specifically, the barrier height (ΦB) is systematically plotted against the metal work function (ΦM) across a range of metal work functions from 3.65 to 5.65 eV. Furthermore, the investigation extends to the saturation currents of three distinct charge transport models for each SiC polytype: thermionic current (TE), thermionic field emission, and field emission. Initial analyses plot saturation currents as a function of concentration within a temperature range of 100–500 K. Subsequent examinations plot saturation currents as a function of temperature across a concentration gradient from 1014 to 1020 cm−3. The comparison between the activation energy and thermal energy at standard room temperature (T = 300 K) yielded results consistent with theoretical predictions, affirming the robustness and applicability of each model within its dominant range. [ABSTRACT FROM AUTHOR]

This study presents the numerical modeling of an underlap gate cavity-integrated reconfigurable silicon nanowire Schottky barrier transistor (UGC-RSiNW SBT) that features a gate-drain underlap region, specifically designed for biosensing applications. The proposed device features a cavity under the control gate on the source side, allowing the immobilization of neutral and charged biomolecules having different dielectric constants. The program gate is specifically placed over the channel-drain Schottky junction to reduce the ambipolar behavior of the device. Using the 2D Poisson equation, we model electrostatic characteristics such as electric potential, threshold voltage, electric field, and drain current. Biomolecules in a cavity can be detected and identified by measuring the variation in threshold voltage ( V Th ), which is caused by the biomolecules' interactions with the local electric field and their influence on charge carrier transport. Simulation results using Silvaco TCAD tools demonstrate significant improvements in sensitivity of the proposed biosensor as compared to conventional RFET biosensors. The study shows a 97.91% increase in the V Th sensitivity of the device for the N-channel and a 16% improvement for the P-channel. The drain current sensitivity and the linearity of proposed biosensor is enhanced upto the values of 2792 and 0.997 respectively in n-mode configuration whereas in p-mode configuration, the drain current sensitivity and the linearity comes out to be 968 and 0.995 respectively. These high sensitivity and linearity values make this biosensor superior to the existing state-of-the-art biosensors. The simulated results were validated when compared with existing literature, confirming the effectiveness of the Silvaco TCAD tool in accurately modeling the biosensor's performance These findings offer valuable insights for developing highly sensitive biosensors for healthcare and biotechnology applications. [ABSTRACT FROM AUTHOR]

Herein, the electrical characteristics and Schottky barrier of Ni/Au and Ni/Ag contacts on the GaN/AlGaN/GaN heterojunction are investigated. Both contacts on the p‐GaN contact layer (Mg: ≈3 × 1019 cm−3) exhibit weak Schottky characteristics. The nonlinear current–voltage (I–V) characteristics are observed, leading to variations in contact resistance (RC) and sheet resistance (Rsh) with changing bias voltage. The Ni/Ag contact achieves a lower Schottky barrier height calculated by using the I–V method. Furthermore, when employing a p++‐GaN layer (Mg: ≈1 × 1020 cm−3) as the contact layer, the Ni/Ag contact forms an Ohmic contact without Schottky characteristics, achieving a satisfactory RC of 30.31 Ω mm. This result demonstrates its viability as a competitive candidate for p‐channel field‐effect transistors' fabrication. [ABSTRACT FROM AUTHOR]

The two‐dimensional characterization of the Au/Ni/thin p+‐GaN/n−‐GaN structure, which is a part of a junction barrier Schottky structure, is demonstrated by scanning internal photoemission microscopy (SIPM) method. In the SIPM photoyield image using a blue laser, small photocurrents based on the internal photoemission effect by electron injection across the metal/semiconductor interface (from Ni to GaN) are detected in the center of the electrode. On the periphery, large photocurrents in the opposite direction are detected. These currents are caused by the hole injection from Ni into p+‐GaN layer and the electrical field in the laterally extended depletion layer at the edge. By using a violet laser, large photocurrents based on the fundamental absorption generated in the depletion layer of the n−‐GaN layer are uniformly detected over the electrode. It is conformed that SIPM can be available for quasi‐three‐dimensional characterization of this structure. [ABSTRACT FROM AUTHOR]

One‐dimensional scanning optical beam‐induced current (OBIC) measurements have been carried out on polymer bulk heterojunction (BHJ) photovoltaic cells with a planar, or lateral configuration. The planar P3HT:PCBM cells have parallel aluminum or gold electrodes that are 390 to 560 micrometers apart. When a focused laser beam is scanned across the electrode gap, photocurrent or photovoltage is recorded as a function of beam position along with the transmission of the excitation beam. Despite the large electrode gap size, cells with symmetric Al/Al electrodes exhibit significant photocurrent and photovoltage which are the highest at the electrode interfaces and null at the cell center. The OBIC in these large planar polymer BHJ cells is attributed to the metal/BHJ blend Schottky junction. The larger Schottky barrier of the Al/BHJ junction gives rise to a stronger OBIC response than the Au/BHJ junction. The photocurrent and photovoltage always have opposite signs and are antisymmetric about the cell center. In asymmetric Al/Au cells, the electrode work function difference contributes an additional built‐in field/potential drop and significantly modifies the photocurrent and photovoltage profiles. The depletion width of the Al/BHJ Schottky junction is 110–120 μm, while the minority electron diffusion length is determined to be 43.8 μm. [ABSTRACT FROM AUTHOR]

Here, synthesis and characterization of TiO2 with different morphologies along with the cost-effective bimetallic decoration on optimized 3D self-assembled nanowire TiO2 (NWT) photocatalyst (Ag/Cu-NWT) with overwhelming hydrogen production rate is reported. All the photocatalysts were well characterized by different characterization techniques. Initially, the effect of morphology change obtained by changing the NaOH concentration has been studied for TiO2. Morphology obtained at 10 M NaOH solution, i.e., NWT (678 μmol/g), showed better hydrogen production than morphology obtained at 5 M (410 μmol/g), 15 M (210 μmol/g), and 20 M (160 μmol/g) NaOH solutions. Further, with the aim to achieve comparable or better activity low-cost photocatalyst as compared to Pt-TiO2 system, NWT was decorated with various Cu percentages and then with a minimal percentage of Ag on an optimized Cu-NWT photocatalyst. The observed trend for photocatalytic hydrogen production has been found to be P25 TiO2 < NWT < 1.0Cu-NWT < 0.5Pt-NWT ≤ 0.1Ag/1.0Cu-NWT. The marked increase by a factor of 103 in hydrogen production for the optimized bimetallic 0.1Ag/1.0Cu-NWT (10,184 μmol/g) photocatalyst compared to P25 TiO2 (99 μmol/g), nearly threefold increment in hydrogen production than an optimized 1.0 Cu-NWT (3907 μmol/g) photocatalyst and comparable hydrogen production as compared to 0.5Pt-NWT (10,050 μmol/g) may be attributed to the successful synthesis of a highly porous NWT morphology, which offers large surface area, increased light absorption combined with the synergistic effects of surface plasmon resonance (SPR), and the Schottky barrier for H+ reduction to H2 gas. The optimization of TiO2 morphology and an inexpensive bimetallic decoration strategy opens up promising opportunities for the development of cost-effective photocatalysts in the realm of energy and environment. [ABSTRACT FROM AUTHOR]

In this paper, a novel 3300 V/40 A 4H-SiC junction barrier Schottky diode (JBS) with a multi-step separated trench (MST) structure is proposed and thoroughly investigated using TCAD simulations. The results show that the introduction of MST expands the Schottky contact area, resulting in a decrease in the forward voltage drop. Furthermore, the combination of the deep P+ shielded region and the central P+ region effectively reduces the leakage current, leading to a 43.7% increase in the blocking voltage compared to conventional 4H-SiC JBS. The effects of the step depth (ds) and the width of the central P+ region (wm) on the device performance are analyzed in depth. In addition, a multi-step trenched linearly graded field-limiting rings (MTLG-FLR) termination ensures a more uniform electric field distribution, and the terminal protection efficiency reaches up to 90%, which further enhances the reliability of the terminal structure. [ABSTRACT FROM AUTHOR]

High-performance field-effect transistors (FETs) based on atomically thin two-dimensional (2D) semiconductors have demonstrated great promise in post-Moore integrated circuits. However, unipolar p-type 2D semiconductor transistors yet remain challenging and suffer from low saturation current density (less than 10 µA·µm−1) and high contact resistance (larger than 100 kΩ·µm), mainly limited by the Schottky barrier induced by the mismatch of the work-functions and the Fermi level pinning at the metal contact interfaces. Here, we overcome these two obstacles through van der Waals (vdW) integration of high work-function metal palladium (Pd) as the contacts onto monolayer WSe2 grown by chemical vapor deposition (CVD) method. We demonstrate unipolar p-type monolayer WSe2 FETs with superior device performance: room temperature on-state current density exceeding 100 µA·µm−1, contact resistance of 12 kΩ·µm, on/off ratio over 107, and field-effect hole mobility of ~ 103 cm2·V−1·s−1. Electrical transport measurements reveal that the Fermi level pinning effect is completely effectively eliminated in monolayer WSe2 with vdW Pd contacts, leading to a Schottky barrier-free Ohmic contact at the metal-semiconductor junctions. Combining the advantages of large-scale vdW contact strategy and CVD growth, our results pave the way for wafer-scale fabrication of complementary-metal-oxide-semiconductor (CMOS) logic circuits based on atomically thin 2D semiconductors. [ABSTRACT FROM AUTHOR]

With the accelerating development of electronic technology, how to effectively eliminate electromagnetic radiation pollution has become a critical issue. Electromagnetic wave (EMW) absorption materials have an irreplaceable position in the field of military stealth as well as in the field of electromagnetic pollution control. In order to cope with the complicated electromagnetic environment, the design of multifunctional and multiband high-efficiency EMW absorbers remains a daunting challenge. In this work, a hierarchical porous molybdenum carbide matrix with a three-dimensional porous structure was designed by salt melt synthesis (SMS) strategy. Furthermore, the relationship between the structure and the impedance matching performance was explored by stepwise modification via ultrathin layered MoS2 nanoflakes. Analysis indicates that the extent of modification of hierarchical porous molybdenum carbide by MoS2 nanoflakes modulates the dielectric performance due to differences in morphology and the introduction of heterogeneous structures, along with a dramatic impact on the impedance matching performance. In particular, the prepared MS/MC/PNC-2 composite exhibits a reflection loss (RL) of -55.30 dB at 2.4 mm, and an ultra-broad effective absorption bandwidth (EAB) of 7.60 GHz is obtained at 2.0 mm. The coordination of structure and component enables the absorber to exhibit strong absorption, wide bandwidth, thin thickness, and multi-band absorption characteristics. Noticeably, the effective absorption performance in the broadband for X and Ku is also satisfying, as well as possessing moderate marine anti-corrosion performance. This study contributes to an in-depth understanding of the relationship between impedance matching and EMW absorber performance and provides a reference for the design of multifunctional, multiband microwave absorbing materials. [ABSTRACT FROM AUTHOR]

Van der Waals (vdWs) stacking of two-dimensional (2D) materials can effectively weaken the Fermi level pinning (FLP) effect in metal/semiconductor contacts due to dangling-bond-free surfaces. However, the inherent vdWs gap always induces a considerable tunneling barrier, significantly limiting carrier injection. Herein, by inducing a sp2 to sp3 hybridization transformation in 2D carbon-based metal via surface defect engineering, the large orbital overlap can form an efficient carrier channel, overcoming the tunneling barrier. Specifically, by selecting the 2D carbon-based X3C2 (X = Cd, Hg, and Zn) metal and the 2D MSi2N4 (M = Cr, Hf, Mo, Ti, V, and Zr) semiconductor, we constructed 36 metal/semiconductor contacts. For vdWs contacts, although Ohmic contacts can be formed at the interface, the highest tunneling probability (PTB) is only 3.11%. As expected, the PTB can be significantly improved, as high as 48.73%, when MSi2N4, accompanied by surface nitrogen vacancies, forms an interface covalent bond with X3C2. Simultaneously, weak FLP and Ohmic contact remain at the covalent-bond-based surface, attributing to the protection of the MSi2N4 band-edge electronic states by the outlying Si-N sublayer. Our work provides a promising path for advancing the progress of 2D electronic and photoelectronic devices. [ABSTRACT FROM AUTHOR]

The present work demonstrates the impact of oxygen flow rates on various properties of TiO2 thin films grown using DC magnetron sputtering. The XRD studies verified the materials' polycrystalline nature. Surface roughness variation with oxygen flow rate was noticed using AFM analysis. The optical energy bandgap was found to vary between 3.42 and 3.75 eV. The electrical and photo-sensing properties of the TiO2 layer were thoroughly examined. The constructed Au/TiO2 junction exhibited a Schottky barrier with a three-order rectification ratio recorded under dark mode. The sensor parameters such as responsivity, detectivity, response time, and linear dynamic range were carefully studied. Under UV (395 nm, 0.5 mW/cm2) irradiation, the diode fabricated at 18% of oxygen flow rate (Au/TiO2-18/ITO) had a photoresponsivity of 0.209 A/W and a steady photo detectivity of 4.03 × 1010 Jones at room temperature. Remarkably, a response time of 520/133 ms was reported. Thus, our findings indicate that Au/TiO2 Schottky diodes might be beneficial for visible, transparent UV photosensors in future optoelectronic applications. [ABSTRACT FROM AUTHOR]

Designing and exploiting visible‐light‐responsive materials that converts solar into chemical energy is promising in achieving green energy sustainability, but addressing low electron–hole separation efficiency and sluggish surface kinetic process remains formidable challenges. Herein, a novel CoP@Ni‐CdS Schottky junction composed of Ni‐doped CdS nanorods and quasi‐metallic CoP nanoparticles is constructed via a simple hydrothermal–calcination method. Experiments and theoretical calculations demonstrate that magnetic Ni‐doping not only induces a spin‐polarized electric field and enhances the built‐in interfacial electric field strength, but also rises the Schottky barrier height at the heterointerface, which synergistically accelerates the separation efficiency of photoinduced charges and modulates the electronic configuration of the active site to optimize the adsorption–desorption behaviors for H2O molecules and H* intermediates. Therefore, the designed CoP@Ni‐CdS catalyst exhibits an exceptional photocatalytic performance with H2 evolution rate of 42.14 mmol g−1 h−1 with the apparent quantum efficiencies of 16.8% at 420 nm, which is 14.14 and 2.21 times higher than that of pristine CdS and Ni‐CdS, respectively. This work provides in‐depth insights into fabricating dual electric fields, tuning the Schottky barrier and modulating the electronic configuration of active sites in Schottky heterojunction for ameliorative photocatalytic activity. [ABSTRACT FROM AUTHOR]

The substitution of noble metals with cost-effective copper nanoparticles (Cu NPs) in the preparation of metal/semiconductor composite catalysts holds significant environmental and economic implications for the degradation of various organic pollutants. However, the development of highly active and stable Cu NPs catalysts has emerged as a key challenge in the progression of non-noble metal catalysts. In this study, the reducibility of glutathione (GSH) was employed to reduce Cu2+ to Cu NPs, resulting in the formation of stable Cu-GSH nanoparticles through S–H bonds. An electrostatic self-assembly strategy was used to load Cu-GSH onto WO3 nanorods, thereby designing a Cu GSH/WO3 catalytic material with highly efficient charge transport efficiency. Under visible light irradiation, 3 wt% Cu GSH/WO3 demonstrated excellent degradation performance for organic pollutants, achieving the degradation of 99.8% of Rh B and 98.6% of TC within 60 minutes. Experimental results from photoelectrochemical (PEC) and electron spin resonance (ESR) analyses indicated that Cu GSH functions as an efficient electron trap, which triggers electron flow driven by the Schottky barrier, capturing the photoexcited electrons from WO3. This greatly enhances the separation efficiency of WO3 carriers and extends the lifetime of the carriers. It is hoped that this work will provide a viable approach for the synthesis of new high-efficiency composite photocatalytic materials. [ABSTRACT FROM AUTHOR]

While the promise of clean and defect‐free MoS2$\left(\text{MoS}\right)_{2}$ nanotubes as quantum electronic devices is obvious, ranging from strong spin–orbit interaction to intrinsic superconductivity, device fabrication still poses considerable challenges. Deterministic transfer of transition metal dichalcogenide nanomaterials and transparent contacts to the nanomaterials are nowadays highly active topics of research, both with fundamental research and applications in mind. Contamination from transport agents as well as surface adsorbates and surface charges play a critical role for device performance. Many techniques have been proposed to address these topics for transition metal dichalcogenides in general. Herein, their usage for the transfer‐based fabrication of MoS2$\left(\text{MoS}\right)_{2}$ nanotube devices is analyzed. Further, different contact materials are compared in order to avoid the formation of a Schottky barrier. [ABSTRACT FROM AUTHOR]

With the advent of the internet era, wearable electronic devices and flexible electronic technology are rapidly emerging, and new resistive random access memory (RRAM) based on flexible substrates have thus gained extensive attention. Here, the flexible Bi 0·95 Er 0·05 FeO 3 /ZnO/La 0·66 Sr 0·34 MnO 3 (BEFO/ZnO/LSMO) heterostructure is prepared on Mica substrate using the sol-gel method. The high resistance state (HRS) to low resistance state (LRS) ratio consistently surpasses 102 under the flat and the 15 mm bending radius state. There is no significant change in the resistive switching (RS) behavior after 30 I–V curve cycles and 103 write/erase operations on the BEFO/ZnO/LSMO heterostructure, which reflects excellent stability. In addition, the device still works properly at 175 °C for dynamic conversion between HRS and LRS. The observed RS behavior in the BEFO/ZnO/LSMO heterostructure is attributed to ion migration and alterations in the potential barrier height at the interfaces. These results suggest that the BEFO/ZnO/LSMO heterostructure based on a flexible Mica substrate plays a crucial role in the development of next-generation portable and flexible electronic systems due to its excellent flexibility and thermal stability. [ABSTRACT FROM AUTHOR]

Anisotropic wet etching of silicon (Si) has been known for decades, but the extraordinary capabilities of this technology to provide highly ordered microphotonic arrays have received limited attention in previous studies. It is shown that these capabilities include: i) a unique self‐terminating etching nature − crucial for achieving uniform arrays over centimeter‐scale wafers, ii) an extraordinary smoothness of the slow‐etching (111) planes, and iii) a precise geometry control including the extent micropyramids or micropyramidal voids are truncated. The combination of these properties transforms this technology into a versatile platform for novel detector and emitter applications in Si photonics. The optical properties of such arrays are studied by finite‐difference time‐domain modeling in two realms represented by different boundary conditions (BCs). Periodic BCs result in Talbot self‐images experimentally observed in this work. Perfectly matched layer BCs describe mesoscale interference effects resulting in the subwavelength focusing properties of micropyramids. Enhancements in the performance of mid‐wave infrared (MWIR) focal plane arrays are demonstrated by monolithic integration of Si micropyramids with silicon‐platinum silicide Schottky barrier photodetectors. Finally, it is shown that Si micropyramidal arrays can be used to enhance light extraction and directionality of quantum sources and infrared scene projectors. [ABSTRACT FROM AUTHOR]

Diamond materials hold great potentials with favorable characteristics for betavoltaic cells, thanks to their simple structure, high conversion efficiency, and radiation robustness. However, to explore its efficiency limit is greatly hindered by the material growth, doping techniques, and device design as well. In this work, a device model based on a diamond metal/intrinsic/p-type (MIP) Schottky barrier architect is analyzed for an accurate prediction of the efficiency limit for the betavoltaic cell based on such a structure. The study takes various factors of significance into account on the betavoltaic cell device characteristics, including the radiation source, thickness and doping concentration of the intrinsic layer, metal work function, as well as the metal/diamond interface traps and traps in the bulk. The current–voltage characteristics and fundamental parameters of the betavoltaic cells are thoroughly analyzed. According to our results, an open-circuit voltage of 2.04 V, a short-circuit current density of 87 nA·cm−2, and a fill factor of 0.9 for the diamond MIP betavoltaic cell can be achieved, which give a maximum energy conversion efficiency of 10.7%, at optimal conditions using 50 nm thick Al metal as the contact layer, 9 μm thick and 1 × 1014 cm−3-doping intrinsic layer, and 10 μm thick and 2 × 1017 cm−3-doping p-layer under a 2 μm 63Ni irradiation. This work also discusses the impact of the interface/bulk traps on the barrier heights of practical Schottky diodes and the device's performance as well. [ABSTRACT FROM AUTHOR]

A key challenge currently for the new ferroelectric refrigeration with high efficiency and environmental friendliness lies in the urgent demand for ferroelectric materials with huge electrocaloric effects (ECE). Ferroelectric polycrystalline ceramics with high ECE stand out as one of the most promising candidates for electrocaloric cooling applications. However, the grain boundary network, as a barrier for the cross‐transmission of charged carriers, widely exists in electrocaloric polycrystalline ceramics and is often neglected in favor of focusing more on composition regulation and structural design. Herein, a grain boundary barrier engineering is proposed that regulates the Schottky barrier at the grain boundary network in the Ba0.8Zr0.2TiO3 ceramics by a maneuverable annealing process and clarifies its critical role in enhancing the ECE of polycrystalline ceramics. As a result, a substantial enhancement of the EC performance (from 0.68 to 1.63 K at 50 °C and 80 kV cm−1, ≈2.4 times) has been achieved in the annealed Ba0.8Zr0.2TiO3 ceramics with a lower Schottky barrier. The microstructural and electrical characterization reveals that the lower Schottky barrier in the grain boundary network facilitates the domain switching and electronic transition, hence resulting in enhanced polarization response and EC performance. [ABSTRACT FROM AUTHOR]

BaTiO 3 -based ceramic is considered to be a fascinating dielectric material with high reliability for ultra-thin multilayer ceramic capacitors (MLCC). Here, we fabricated a series of acceptor-doped BaTiO 3 (Mg: 0.2, 0.5, 1.0, 1.5, 2.0, and 5.0 mol%) ceramics with Al 2 O 3 and SiO 2 as sintering additives. With an increase in Mg concentration, the insulation resistance of the BaTi 1- x Mg x O 3 ceramics initially increases and then decreases, in which the 0.5 mol% Mg-doped ceramic achieves superior degradation behavior. The reason is that with the incorporation of the acceptor ion Mg2+, the charge compensation mechanism in the system changes. Initially, barium vacancy is generated, which is gradually dominated by oxygen vacancy. Analysis indicates that the segregation of the acceptor state barium vacancy to the grain boundary increases the schottky barrier of the grain boundary, while the gradual increase of the donor state oxygen vacancy reduces the reliability of the ceramic. This study provides a comprehensive overview illustrating the significant role of point defects in the potential barrier of the grain boundary in acceptor-doped BaTiO 3 ceramics. It identifies a pathway to achieve high reliability in BaTiO 3 -based MLCC. [ABSTRACT FROM AUTHOR]

This research presents a comprehensive study of a Schottky diode fabricated using a gold wafer and a bilayer molybdenum disulfide ( MoS 2 ) 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/ MoS 2 interface, characterized by a distinct nonlinear I–V relationship. Comparative analysis revealed that the Au/ MoS 2 diode significantly outperforms a traditional W/Si structure in terms of rectification performance. The Au/ MoS 2 diode exhibited a current density of 1.84 × 10 − 9 A/ cm 2 , substantially lower than the 3.62 × 10 − 5 A/ cm 2 in the W/Si diode. Furthermore, the simulated I–V curves of the Au/ MoS 2 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/ MoS 2 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/ MoS 2 junction. This research provides insights into the electronic properties of Schottky contacts based on two-dimensional MoS 2 , particularly the relationship between electronic barriers, system dimensions, and current flow. The demonstration of high-ideality-factor Au/ MoS 2 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. [ABSTRACT FROM AUTHOR]

Herein, AlGaN/GaN lateral diode with the Schottky‐Metal‐Insulator‐Semiconductor (MIS) cascode anode (CALD) to optimize forward voltage drop (VF) and reverse leakage current (ILEAK) trade‐off is proposed. In the CALD device, a normally‐on Ni/HfO2/AlGaN MIS‐controlled channel as well as a lateral Ni/GaN Schottky contact are cascoded at the anode. The designed normally‐on MIS‐controlled channel has high electron concentration at forward bias and prevents high electric‐field at reverse bias, which ensure both low VF and low ILEAK. Meanwhile, the Ni/GaN Schottky contact with a high Schottky barrier height further suppresses the ILEAK. As a result, the fabricated CALD demonstrates an optimized VF–ILEAK trade‐off relationship, including a low VF of 1.6 V and a low ILEAK of 5.2 × 10−8 A mm−1 (at reverse voltage of 400 V), together with a high breakdown voltage (BV) >700 V. These high performances suggest that the CALD can be a promising candidate for GaN power diode applications requiring a better VF–ILEAK trade‐off. [ABSTRACT FROM AUTHOR]

Dynamic random-access memory (DRAM) has been scaled down to meet high-density, high-speed, and low-power memory requirements. However, conventional DRAM has limitations in achieving memory reliability, especially sufficient capacitance to distinguish memory states. While there have been attempts to enhance capacitor technology, these solutions increase manufacturing cost and complexity. Additionally, Silicon-based capacitorless memories have been reported, but they still suffer from serious difficulties regarding reliability and power consumption. Here, we propose a novel Schottky barrier memory (SBRAM), which is free of the complex capacitor structure and features a heterojunction based on bandgap engineering. SBRAM can be configured as vertical cross-point arrays, which enables high-density integration with a 4F2 footprint. In particular, the Schottky junction significantly reduces the reverse leakage current, preventing sneak current paths that cause leakage currents and readout errors during array operation. Moreover, the heterojunction physically divides the storage region into two regions, resulting in three distinct resistive states and inducing a gradual current slope to ensure sufficient holding margin. These states are determined by the holding voltage (Vhold) applied to the programmed device. When the Vhold is 1.1 V, the programmed state can be maintained with an exceptionally low current of 35.7 fA without a refresh operation. [ABSTRACT FROM AUTHOR]

Two-dimensional (2D) multiferroic materials are recognized as promising candidates for next-generation nanodevices due to their tunable magnetoelectric coupling and distinctive physical phenomena. In this study, we proposed a novel 2D multiferroic van der Waals heterostructure (vdWH) by stacking atomic layers of ferroelectric In2Se3 and ferromagnetic MnI3. Using first-principles calculations, we found that the MnI3/In2Se3 vdWH exhibit robust metallic conductivity across various spin and polarization states, preserving the distinctive band characteristics of isolated In2Se3 and MnI3. However, the alignment of Fermi levels causes the conduction band minimum (CBM) and valence band maximum (VBM) of In2Se3 and MnI3 to shift relative to their original band structures. Remarkably, the MnI3/In2Se3 with the upward polarization state of In2Se3 exhibits an Ohmic contact. Switching the polarization direction of In2Se3 from upward to downward can transform the MnI3/In2Se3 vdWH from an Ohmic contact to a p-type Schottky contact, while also modifying its dipole moment, magnetic strength and direction. Based on these properties of MnI3/In2Se3 vdWH, we designed the field-effect transistors (FETs) with high on/off rates and nonvolatile data storage device. Furthermore, the Schottky barrier heights (SBHs), magnetic moment, and dipole moment of MnI3/In2Se3 vdWH can also be effectively regulated by reducing the interlayer distance. With the continuous reduction of the interlayer distance of MnI3/In2Se3 vdWH, its easy magnetization axis is expected to shift from in-plane to out-of-plane. These findings offer new insights for the design and development of the next-generation spintronic and nonvolatile memory nanodevices. [ABSTRACT FROM AUTHOR]

By employing the classic system poly(3-hexylthiophene-2,5-diyl): [6,6]-phenyl-C61-butyric acid methyl ester (P3HT:PC61BM), organic bulk heterojunction films were applied on an indium tin oxide substrate using a one-step spin-coating method, without requiring any complex manufacturing processes, to obtain self-powered photodetectors (PDs) with a simple preparation process. The fullerene material was introduced to create a bulk heterojunction film with proper phase separation and greatly enrich the donor/acceptor dissociation interface, thus improving the high exciton binding energy and short exciton diffusion distance. The built-in electric field formed by the Schottky junction at the interface between the active layer and electrode can enhance the separation of excitons and the transport of charge carriers, realizing optical detection without external energy sources. Moreover, femtosecond transient absorption was employed to investigate the exciton dynamics in organic films and analyze the working mechanism of self-powered detection performance. The long-lived behavior of carriers and the formation of charge transfer states were further verified, which contributed to the enhanced performance of the device. As a result, the self-powered PD-based Schottky bulk heterojunction presents a high light on/off ratio of over 104 (0 V) and fast response speed with rise and decay times of 33 and 36 µs, respectively, under a 532 nm light illumination. These results provide theoretical and experimental verification of this technique for the development of self-powered PDs in the field of organic materials. [ABSTRACT FROM AUTHOR]

Using first-principle calculations, metal–semiconductor (MS) contact of YX2 (Y=Ta, Nb; X=S, Se, Te) and MX2 (M=Mo, W; X=S, Se, Te) monolayers in the shape of YX2–MX2 van der Waals Heterostructures (vdWHs) are fabricated. Electronic structure, type of the Schottky contact and height of Schottky barrier at the interface of YX2–MX2 vdWHs are investigated. Stabilities of these systems confirmed via AIMD simulation and binding energies calculations. Electronic band structures confirm the metallic nature of YX2–MX2 MS vdWHs. Specific cases of the YX2–MX2 MS vdWHs have quite small (high) effective mass (carrier mobility), hence show potential for nanoelectronic devices. Workfunction and transfer of charges among the layers of YX2–MX2 MS vdWHs are also evaluated via electrostatic potential. A Schottky contact is established, while fabricating YX2–MX2 MS vdWHs. The calculated Schottky barrier height (SBH) show that YX2–MX2 (Y=Ta, Nb, M=Mo, W; X=S, Se, Te) vdWHs, initiate p-type of Schottky contact, while specifically, TaX2–MTe2 (M=Mo, W) and NbTe2–MoS2 and NbTe2–WS2 MS vdWHs initiate n-type of Schottky contact due to their higher Bn values. The SBH values are miniature compared to traditional MS contacts, but they are consistent with previous 2D based MS contacts. These observations indicates the potential of YX2–MX2 MS vdWHs for high-performance device application. [ABSTRACT FROM AUTHOR]

Recent exciting developments in synthesis and properties study of the germanane (GeH) mono‐layer have inspired us to investigate the structural and electronic properties of the van der Waals heterostructures (HTS) of GeH/InSe and GeH/In2Se3 through a first‐principles methodology. In this study, structural and electronic properties of the HTS are examined thoroughly. GeH/InSe and GeH/In2Se3 are determined as n‐type Schottky with a Schottky barrier height (SBH) of 0.40 eV and n‐type ohmic, respectively. GeH/InSe turns out as a semiconductor with a direct bandgap of 0.62 eV, while GeH/In2Se3 is seen to be a metal. The results show that changing of the bandgap and SBH in very small values. For GeH/In2Se3 the effects are even less substantial, as the metallic or n‐type nature of the material does not change. The biaxial strain and electric field have more tangible effects on the characteristics of the HTS. A mixture of compressive and tensile strain is seen to have the capability of changing GeH/InSe into a metal and at the same time transform it to an n‐type/p‐type ohmic or p‐type Schottky contact. The results given here can guide future research in the field of HTS and especially GeH‐based devices. [ABSTRACT FROM AUTHOR]

Elemental tellurium electrical switch, relying on a transient crystal–liquid–crystal phase transition, has recently been proposed as a promising selector candidate for the next‐generation 3D high‐density memory, bridging performance gap in today's computer. Further miniaturization of the switch cell to increase memory density strongly depends on the scalability of the tellurium film, which, however, has not been experimentally studied. Herein, the tellurium films are prepared with the thickness downscaled from 400 to 2 nm and a significant increase is found in the bandgap from 0.29 to 0.91 eV, as predicted by ab initio molecular dynamics. Interestingly, the as‐deposited tellurium films with a thickness above 3 nm are in the crystalline trigonal phase, whereas 2 nm thick film suddenly becomes amorphous, observed by both Raman and transmission electron microscopies. In this finding, since the leakage current of the elemental tellurium switch is determined by both the Schottky barrier between tellurium/electrode interface and the bandgap of the tellurium film, a reduction in leakage current is predicted with further miniaturization. [ABSTRACT FROM AUTHOR]

Establishing Schottky barriers is a key tactic for enhancing the separation of photogenerated charge carriers and improving photocatalytic efficiency. Herein, a self‐assembled metal cocatalyst, NiCo2S4 nanorod, is loaded onto the flower‐like Zn3In2S6 microsphere via a hydrothermal method. Under visible light irradiation, the NiCo2S4/Zn3In2S6 composite material achieves a peak H2 production rate of 3436.72 μmol g−1 h−1 within 6 h, marking a 5.4 times greater increase compared to pristine Zn3In2S6. This outperforms the maximum H2 production rate of Pt/Zn3In2S6‐1% within the same 6‐hour timeframe, which is 3323.05 μmol g−1 h−1. Additionally, the apparent quantum efficiency reaches 7.86% at 420 nm. The outstanding photocatalytic activity stems from the synergistic effects between the visible‐light‐active Zn3In2S6 and the conductive cocatalyst NiCo2S4, facilitating spatial electrical promotion. In particular, the formation of a Schottky junction at the interface of NiCo2S4/Zn3In2S6 enables prompt electron transfer to NiCo2S4 nanorods, preventing backflow and thereby promoting the efficient separation of photogenerated charge carriers. Finally, a plausible reaction mechanism is proposed, drawing from the electrochemical characterization results. Thus, this research provides a new approach for designing metal‐semiconductor photocatalysts that are efficient in photocatalytic H2 production through water splitting. [ABSTRACT FROM AUTHOR]