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This paper presents the fabrication procedure of TiO2 passivated field plate Schottky diode and gives a comparison of Ni/Au/n-GaN Schottky barrier diodes without field plate and with field plate of varying diameters from 50 to 300 µm. The influence of field oxide (TiO2) on the leakage current of Ni/Au/n-GaN Schottky diode was investigated. This suggests that the TiO2 passivated structure reduces the reverse leakage current of Ni/Au/n-GaN Schottky diode. Also, the reverse leakage current of Ni/Au/n-GaN Schottky diodes decreases as the field plate length increases. The temperature-dependent electrical characteristics of TiO2 passivated field plate Ni/Au/n-GaN Schottky diodes have shown an increase of barrier height within the temperature range 300…475 K.

The short circuit (SC) behavior of a newly developed GaN-HEMT/SiC-JFET cascode device is investigated in this work. The reverse leakage current through the drain-side PN junction ( IR ) of the SiC JFET under SC conditions is measured simultaneously during the SC event. IR of the SiC JFET increases to 6.4 A at the end of a 5-μs nondestructive SC pulse. The increase of IR during the SC pulse induces a turning point in the SC current waveform and a dramatic negative threshold voltage shift (>30 V) in the SiC JEFT, resulting in high transient drain-to-source voltage in the GaN HEMT. The underlying mechanism is associated with the increase of local potential in the P-type layer of the SiC JFET with inevitable spread resistance ( R SPD). It is suggested that reducing R SPD can improve SC capability and high IR should be considered in SC failure mechanism analysis and the design of external gate resistance of the SiC JFET.

This article presents a fully energy-autonomous temperature-to-time converter (TTC), entirely powered up by a triboelectric nanogenerator (TENG) for biomedical applications. Existing sensing systems either consume too much power to be sustained by energy harvesting or have poor accuracy. Also, the harvesting of low-frequency energy input has been challenging due to high reverse leakage of a rectifier. The proposed dynamic leakage suppression full-bridge rectifier (DLS-FBR) reduces the reverse leakage current by more than 1000 $\times $ , enabling harvesting from sparse and sporadic energy sources; this enables the TTC to function with a TENG as the sole power source operating at $\mu \text{m}$ 1P6M CMOS technology, consuming 0.14 pJ/conversion with 0.014-ms conversion time.

In this letter, the ultrafast reverse recovery β -Ga2O3 Schottky barrier diode (SBD) with improved breakdown voltage is proposed and investigated experimentally. It features the compound termination, consisting of air space field plate and thermal oxidation terminal. The compound termination not only reduces high-density interface states at the dielectric/Ga2O3 interface and the electron concentration in the oxidation terminal, but also modulates the electric-field distribution and suppresses the peak electric-field at the bottom of anode. Therefore, the reverse leakage current is suppressed as well as the reverse recovery and breakdown characteristics are improved effectively. The Ga2O3 SBDs with the diameter of 1000 μm obtain ultrashort reverse recovery time of 7.5 ns and ultralow reverse recovery charge of 1.0 nC at di / dt = 50 A/μs with its breakdown voltage up to 400 V, maintaining good rectification characteristics. The temperature-dependences of both forward conduction and reverse recovery characteristics are discussed in temperature range from 300 to 500 K. The results prove that the superior electronics performance of the β -Ga2O3 SBDs with good electronics thermal tolerance can overcome the low thermal conductivity of β -Ga2O3 to a certain extent. The fabricated β -Ga2O3 SBDs have great potential for high power and high-frequency applications.

In the modeling of PV modules under shading and low illumination, a complete description of reverse bias behavior at the cell level is critical to understanding module response. This is particularly important when dealing with high voltage configurations such as tandem and shingled modules. Current simulation studies often do not account for the effects of incident light when dealing with operating voltages approaching cell breakdown. In this article, we investigate the illumination dependence of leakage current at the onset of breakdown in crystalline silicon solar cells. A study of the most popular cell technologies in the market today reveals a light induced effect under reverse bias that is prominent for p-type and small for n-type cells. Additionally, this effect is found to be larger in mono c-Si than multi c-Si cells. Because this phenomenon is not captured in current breakdown models such as Bishop's equation, we propose a split-cell model to describe partial shading in p-type cells. The outlined approach divides the cell into two parallel regions and is advantageous for its procedural simplicity as well as its ability to generalize effects from complex shading profiles.

We successfully fabricated the Al0.58Ga0.42N-based solar-blind ultraviolet (UV) Schottky type photodetectors (PDs). The crystalline quality, morphology and dislocation information of the Al0.58Ga0.42N epitaxial layer have been obtained by detailed characterizations of high-resolution X-ray diffraction (XRD), atomic force microscopy (AFM) and transmission electron microscope (TEM). In addition, the responsivity of the PD with cutoff wavelength of 260 nm is 0.15A/W at −5V and 0.12 A/W at 5 V, respectively. Detailed carrier transport models are explored to analyze the I-V-T characteristics measured between 300 and 425 K, in order to provide more information for analyzing the reverse leakage mechanisms in the Al0.58Ga0.42N solar-blind PD. It is convincingly demonstrated that thermionic-field emission and Poole–Frenkel emission can accurately describe the low-bias I-V characteristics and the high-bias I-V characteristics, respectively.

The effects of initial oxygen concentration on the reverse leakage current of PIN rectifier diodes were studied. We fabricated the PIN rectifier diodes with different initial oxygen concentrations, and analyzed the electrical properties, anisotropic preferred etching by means of optical microscopy, Fourier transform infrared spectroscopy and transmission electron microscopy. It is pointed out that the reverse leakage current increases exponentially with the increasing initial oxygen concentration. Furtherly, we researched and analyzed the mechanism of the effects of initial oxygen concentration on the reverse leakage current of PIN rectifier diode. It is shown that the oxygen precipitations present in an “S” curve with increasing initial oxygen concentration after high temperature diffusion. The main reason is that the nucleation and growth of oxygen precipitation at high temperature induce bulk oxidation-induced defects (B-OSF), which are mainly dislocations, and a small amount of rod stacking faults. The density of B-OSF increases with the increasing initial oxygen concentration. The existence of B-OSF has great effects on the reverse leakage current of PIN rectifier diode.

In this article, a $\beta $ -Ga2O3 metal-interlayer-semiconductor Schottky barrier diode (MIS-SBD) using Al-reacted aluminum oxide as the interlayer is demonstrated for the first time and compared with conventional metal-semiconductor (MS) Schottky barrier diode (SBD). The aluminum oxide is formed by sputtering a thin Al layer on Ga2O3 substrate and then annealed in O2 at 300 °C. With the insertion of Al-reacted interlayer, the SBD subthreshold swing (SS) is significantly improved to 61 mV/dec with an average current range of >6 orders. Example of atomic layer deposited (ALD) Al2O3 as the interlayer is also fabricated and characterized. ${J}$ – ${V}$ study corrected by Gaussian distribution model shows that all the samples statistically exhibit similar mean barrier heights (BHs). This indicates that the interlayer hardly affects the electrostatic field and band bending as experienced by carrier injections. ${C}$ – ${V}$ study provides different BH results in different sample setups. The result proves that Al-reacted interfacial layer helps eliminate interface degradation as compared with ALD Al2O3. Overall, MIS-SBD by Al-reaction method exhibits improved SS, reduced reverse leakage current ( ${I}_{0}$ ), low ideality factor, good ON-OFF ratio ( $> 10^{9}$ ), and minimized interface charges as compared with its respective counterparts. The result of this article serves as a promising interface engineering technique for Ga2O3-based SBD designs.

Dopant segregation (DS) technique has been extensively employed to tune Schottky barrier heights (SBHs) of NiSi/Si diodes, either leading to reduced specific contact resistivity ( $\rho _{\text {c}}$ ) in source/drain (S/D) Ohmic contacts, or enhanced current drivability in Schottky barrier S/D MOSFET (SB-MOSFET) where metallic NiSi is employed as S/D. A capacitance–voltage ( ${C}$ – ${V}$ ) method is usually adopted to reliably extract the SBHs of NiSi/Si for investigating the effectiveness of such a DS technique. In order to avoid large reverse leakage current which rules out the possibility of SBHs extraction during ${C}$ – ${V}$ measurements, dopants with opposite polarity to that in epitaxial Si substrate segregate at the NiSi/Si interface, for instance, boron DS (B DS) for NiSi/n-Si and arsenic DS (As DS) for NiSi/p-Si. This, however, raises one critical question, i.e., NiSi/p+-Si (B DS)/n-Si and NiSi/n+-Si (As DS)/p-Si are p-n or Schottky junctions. In this work, a dedicated circuit is devised to distinguish the type of as-fabricated NiSi/Si diodes with DS based on different switching mechanisms between p-n and Schottky junctions.

High-performance AlGaN/GaN lateral Schottky barrier diodes (SBDs) with recess structure and dual metal nitride anodes were demonstrated. With high work-function and nonrecess structure, a NiN anode enhances the breakdown voltage (BV), while a TiN anode reduces the turn-on voltage ( ${V}_{ \mathrm{\scriptscriptstyle ON}}$ ) due to its low work-function and contact to the two-dimensional electron gas (2DEG) layer directly on a recess structure. As the length of the NiN anode ( ${L}_{r}$ ) on the nonrecess region decreases from 75 to 3 $\mu \text{m}$ , ${V}_{ \mathrm{\scriptscriptstyle ON}}$ is reduced from 0.56 to 0.30 V, while the reverse leakage current slightly increases from ${3} \times {10}^{-{4}}$ to ${2} \times {10}^{-{3}}$ A/cm2 at the bias of −10 V. The lateral AlGaN/GaN SBD with a ${L}_{r}$ of 3 $\mu \text{m}$ at a distance of cathode–anode ( ${L}_{\text {AC}}$ ) of 20 $\mu \text{m}$ achieves a high BV of 1.62 kV, an ultralow ${V}_{ \mathrm{\scriptscriptstyle ON}}$ of 0.30 V and a small capacitance of 6.0 pF at zero bias with little degradation on ON-resistance, indicating superior potential application in high-frequency and high-power devices.

The change in the electrical properties of 4H-SiC Schottky barrier diodes (SBDs) irradiated by 6 MeV Au ions at low temperature (LT) is investigated. The SBDs are characterized by current–voltage (I-V) and capacitance–voltage (C-V). The SRIM software is used to calculate the Au ion transportation process. The experimental results indicate that the ideality factor (n) and the reverse leakage current (IR) increase, and Schottky barrier height (SBH) decreases with the increase in fluence. It is found that series resistance (RS) and effective impurity concentration (ND) are recovered at 5 × 1015 ions/cm2. Calculation results show that the mental layer can prevent most of the Au ions, while the secondary particles will enter the SiC layer. Therefore, these results demonstrate that the secondary particles induce many defects at the metal-SiC interface and the SiC epitaxial layer after LT heavy ion (HI) irradiation.

We propose self-rectifying resistive random access memory (RRAM) synapse to prevent reverse leakage current problem which occurs when RRAM is integrated with integrate and fire (IF) circuit in spiking neural network (SNN). Ni/W/SiN x /n-Si RRAM was fabricated by varying the bottom electrode (BE) doping concentration and their rectifying characteristics were analyzed. Low BE doping concentration device showed self-rectifying characteristics without any additional selector or diode device. Furthermore, hardware-based system-level simulation was conducted to evaluate the effect of self-rectifying RRAM synapse on MNIST classification accuracy. About 93.34% accuracy was obtained using the proposed RRAM.

In this article, a 15-W quadruple-mode reconfigurable wireless power-receiving unit with high efficiency for Inductive coupling and magnetic resonance-based standards, such as wireless power consortium (WPC), power matters alliance (PMA), alliance for wireless power (A4WP), and magnetic secure transmission (MST) applications is proposed. Quadruple-mode gate controller(QMGC) is proposed in quadruple-mode synchronous rectifier to manage sizes of core and drivers which results in maximum power conversion efficiency (PCE) for each mode based on conduction and switching losses. In QMGC, switchable zero voltage and current sensing block is proposed for WPC/PMA to maximize PCE regardless of load current variations. For A4WP mode, a digitally controlled delay adjustment block is adapted to minimize power consumption while compensating for delay which results in reverse leakage current and power loss. Finally, for MST mode, low power TX (LPTX) block is implemented to minimize current consumption so that burden on battery can be minimized. A high-resolution current sensor is proposed in low-drop out regulator to sense current for overcurrent limit and overcurrent protection. The measured PCE of proposed system at 15 W are 95.3% and 92.3% for WPC/PMA and A4WP mode, respectively. For MST, power consumption is reduced to 35% courtesy LPTX block.

This work reports a $\beta $ -Ga2O3 double-barrier Schottky barrier diode (DBSBD) with both low turn-on voltage and low reverse leakage current by using Ni and PtOx as the anode electrode. The barrier height of PtOx-based diode can be effectively modulated from 1.26 to 1.62 eV by adjusting oxygen pressure during sputtering processes. Combining the maximum work function of PtOx electrode with the optimization of the electrode ratio of Ni and PtOx, the DBSBD with an electrode diameter ratio of $\text{D}_{\text {Ni}} /\text{D}_{\text {PtOx}}= {75}/{150} \mu \text{m}$ not only exhibits a high forward current of 470.9 A/cm2 (at 3.5 V), a low on-resistance of 4.1 $\text{m}\Omega ~\cdot $ cm2 and a low turn-on voltage of 1.13 V, but also possesses a relatively low reverse leakage current of ${1.2}\times {10}^{-{7}}$ A/cm2 (at −100 V), which is more than one order of magnitude lower than that of the Ni-SBD. Silvaco TCAD simulation reveals that such optimization can be attributed to the suppression of edge leakage current due to the double-barrier contact. Therefore, the strategy of double-barrier design can balance the forward and reverse characteristics in SBD, providing a new device structure for advanced power electronics.

This paper demonstrates the electrical and current transport properties of prepared Ti/α-amylase/p-InP metal/polymer/semiconductor (MPS) junction by current–voltage (I–V) approach. The microstructure of the fabricated MPS junction is confirmed by transmission electron microcopy (TEM) measurement. The MPS junction exhibited a good rectification nature over the Ti/p-InP metal/semiconductor (MS) junction. The derived barrier height (BH) of MPS junction (0.78 eV) is higher than the MS junction (0.70 eV), that indicates the BH is influenced by the polymer layer. The BH is extracted by the I–V, Z(V)–Vd plot, Cheung’s function, α(V)–V plot, Norde method and Ψs–V plot and found the values are comparable with one another, which indicates their steadiness and validity. The estimated interface state density (NSS) of the MPS junction is less than the MS junction, suggesting that the α-amylase layer decreased the NSS value. The forward log (I)–log (V) plot of the MS and MPS junctions reveals the ohmic nature at lower-bias region and space-charge-limited conduction at higher-bias region. Results reveal that the reverse leakage current conduction mechanism of the MS and MPS junctions is governed by Poole–Frenkel emission in lower-bias region, whereas, at higher bias region, Schottky emission is dominant current conduction mechanism. These exploration results establish that the α-amylase polymer layer is potential for use in organic–inorganic devices.

Fabrication of dual-barrier planar (DBP) structure diamond Schottky barrier diodes (SBDs) with only Ni Schottky contact was carried out by rapid thermal annealing. Ni/Au narrow stripes were first patterned on $\text{p}^{-}$ layer and annealed at 550 °C to decrease Schottky barrier height and form low barrier contact. Then, Ni/Au Schottky electrodes were deposited on the window area between stripes to serve as high barrier contact. Ti/Pt/Au ohmic contact was formed on the back side of $\text{p}^{+}$ diamond substrate. The fabricated DBP structure SBDs exhibit low forward voltage drops compared with single high barrier diode, and reverse leakage current densities of two to three orders of magnitude smaller than that of single low barrier diode. The influence of stripes area proportion on device properties was investigated and the barrier height can be adjusted by changing dual-barrier ratio. This new device structure displays a small power dissipation of 0.54 W/cm2, which is a promising technology for high power diamond diodes.

This paper presents an overall optimization procedure and the electrical performances of 1.2 kV/10 A 4H-SiC junction barrier Schottky (JBS) diodes with high current density. To achieve high current density, the epi-layer, the design parameters for active region including p-grid width and cell pitch, and the field limiting ring for edge termination were optimized with analytic calculation to estimate forward electrical performances and with Silvaco atlas™ simulator to estimate reverse electrical performances. Based on the systematic design, the JBS diodes were fabricated and electrically characterized. The experimental results showed that the breakdown voltage (BV) of JBS diode was significantly sensitive to field limiting ring (FLR) space and that the JBS diode with the ratio of pure Schottky contact area to total active area of 0.75 and the FLR space of 1.25 μm had optimum electrical performances such as a forward current density of 370 A/cm2, a reverse leakage current below 20 μA at the reverse anode voltage of 1.2 kV, and the BV of 1400 V. These were in coincidence with the simulation results within 10% error.

We analyzed current conduction mechanisms (CCMs) of the (Au/Ti)/Al2O3/n-GaAs (MIS) type SBDs in the wide temperature range (80-380 K) by 30 K steps using reverse bias current-voltage (I-R-V-R) characteristics. In general, the values of barrier-height (BH) obtained from the forward bias current-voltage (I-F-V-F) and reverse bias current-voltage (I-R-V-R) characteristics increase with increasing temperature and this change is in-agreement with the reported negative-temperature coefficient bandgap of semiconductor (alpha = Delta Eg/Delta T) or BH for ideal SDs. However, the change in BH at lower temperatures becomes more pronounced. The value of BH obtained from the I-R-V-R data is lower than that obtained from I-F-V-F especially under room temperatures. The necessary barrier height (phi(t)) for electron emission from the trap state was obtained from the ln (I-R) - E-0.5, (E = V-R/d), plot as 1.25 eV to (at 80 K) 0.91 eV (at 380 K), respectively. This change in the phi(t) with temperature is in agreement with the reported alpha value of the Eg for GaAs. The reverse leakage current mechanism in this study was assessd for various temperatures using Schottky emission (SE), Poole-Frenkel emission (PFE), Trap-Assisted Tunneling (TAT), and ohmic conduction mechanisms. The evaluation of the I-R-V-R characteristics shows that the ohmic and TAT are the most dominant conduction mechanisms rather than others.

Surface treatment is quite vital to reduce the reverse leakage current and improve the current On–Off ratio of gallium nitride (GaN) quasi-vertical Schottky barrier diode (SBD). In this work, we report a new nondestructive low temperature supercritical CO2 fluid (SCF) nitridation technology to treat the surface of GaN and substantially reduce the leakage current of GaN quasi-vertical SBD. The X-ray photoelectron spectroscopy (XPS) reveals the increased nitriding degree and oxygen doping degree in the form of GaO x after the SCF process results in the leakage performance improvement. As a result, the defects at metal/semiconductor interface are passivated. Also, because of NH-2 and OH− generated from the SCF process, the surface peak electric field of n−GaN decreases, and thus the breakdown voltage is enhanced. The reverse leakage current density is reduced by more than three orders of magnitude from $3.7\times 10^{-{6}}$ to $3.52\times 10^{-{9}}$ A/cm2 (at −3 V) and the ON-/ OFF-current ratio is improved by three orders from $8\times 10^{{7}}$ to $5.74\times 10^{{10}}$ .

A Ka -band AlGaN/GaN metal–insulator–semiconductor high-electron-mobility transistor (MIS-HEMT) with SiN gate dielectric grown by plasma-enhanced atomic layer deposition (PEALD) is demonstrated. The gate reverse leakage current in a controlled HEMT is reduced by about three orders of magnitude by the PEALD-SiN, contributing to an improved breakdown voltage of 92.5 V (source–drain separation of $2.0~\mu \text{m}$ ) in the fabricated MIS-HEMTs. The MIS-HEMTs also feature small threshold voltage hysteresis in dc transfer and capacitance–voltage characterizations, suggesting a good PEALD-SiN/AlGaN interface. The fabricated MIS-HEMTs deliver a high output power density of 7.16 W/mm and a peak power-added efficiency of 60.3%, respectively, at ${V}_{\text {DS}} =30$ V and ${V}_{\text {DS}} =10$ V in pulse mode at 28 GHz. PEALD-SiN could be a compelling gate dielectric for fabrication of high-power and high-efficiency MIS-HEMTs.

Carbon impurities are common defects in monocrystalline silicon and have negative effects on the electrical performance of electronic devices. In the present work, the effects of carbon impurities in monocrystalline silicon on the electrical properties of PIN rectifier diodes with different carbon concentrations were investigated by electrical performance tests, anisotropic preferential etching, Fouriertransform infrared spectroscopy (FTIR), transmission electron microscopy (TEM), and energy-dispersive spectroscopy (EDS). It was found that with the increasing carbon concentration, the reverse leakage current (IR) increased rapidly, the time of reverse recovery (TRR) and the ratio of the average reverse withstand voltage to the theoretical value decreased rapidly, and the forward voltage drop (Vf ) increased significantly. Further, with the rising carbon concentration, bulk oxidation-induced defects (B-OSF) changed from dislocation-dominated to stacking fault-dominated and the stacking fault length increased gradually. [Ci-Oi] carbon centers of interstitial carbon and interstitial oxygen with a wide absorption band were detected by FTIR. The existence of stacking dislocation defects and carbon-oxygen complexes [Ci-Oi] was confirmed by TEM and EDS. It was pointed out that substitutional carbon (Cs) captured interstitial silicon atoms, changed into interstitial carbon (Ci) in the silicon substrate, and formed [Ci-Oi] complexes of interstitial carbon and interstitial oxygen after high-temperature diffusion, and these complexes acted as heterogeneous nucleation centers to promote the formation and growth of oxygen precipitation. Due to the volume strain energy, interstitial silicon atoms and dislocations were continuously released to promote oxygen atoms during the growth process of carbon-oxygen complexes. The formation and growth of B-OSF defects caused the “impurity piercing pipe”effect. These defects acted as defect recombination centers and deteriorated the electrical performance of the PIN rectifier diodes.

We determined the optical and electrical characteristics of GaN-based, ultraviolet micro light emitting diodes (microLEDs). Such microLEDs are essential to next-generation high-resolution micro-displays. Square-shaped microLEDs of different sizes (side lengths: 5-50 μm) were designed. The peak emission wavelength of these devices shifted

This letter reports on the suppression of reverse leakage current ( ${I} _{r}$ ) in $\beta $ -Ga2O3 Schottky barrier diodes (SBDs) through Schottky barrier modification by a low power CF4-plasma treatment prior to Schottky metal deposition. Revealed by an x-ray photoelectron spectroscopy (XPS) analysis, the fluorine-plasma treatment brought an incorporation of fluorine ions and depletion of silicon donors in the near surface region of the $\beta $ -Ga2O3, and thus raised its surface potential by around 0.14 eV. Furthermore, insulating GaF x was likely created at the Schottky interface. Attributed to the fluorine-plasma- modified Schottky barrier, a reduced ${I} _{\mathbf {r}}$ by around four orders of magnitude and enhanced blocking voltage ( ${V} _{{block}}$ ) from 150 V to 470 V at ${I} _{r} = 100\mu $ A/cm2 have been achieved without degrading the forward characteristics. Different from the untreated device whose ${I} _{r}$ was purely governed by the thermionic field emission (TFE), the fluorine-plasma-treated SBD showed a greatly suppressed TFE-current until a space-charge limited current (SCLC) started to dominate at around −500 V.

In this paper, we pose reverse leakage current issue which occurs when resistive random access memory (RRAM) is used as synapse for spiking neural networks (SNNs). To prevent this problem, 1 diode-1 RRAM (1D1R) synapse is suggested and simulated to examine their current rectifying chracteristics, Furthermore, high density of 1 K 3D 1D1R synapse array structure and its process flow are proposed.

The first step of preparing black silicon solar cells by Ag metal-assisted chemical etching method (Ag-MACE) is to remove the saw damage layer on the surface of diamond wire saw multi-crystalline silicon wafers. The usual way to do this is with a hot solution of KOH. However, the surface of silicon wafers processed in large quantities in this way will have many white spots and stains. These white spots and stains are the saw damage layer that have not been removed cleanly. They affect not only the appearance of the solar cells, but, most importantly, the subsequent uniform deposition of silver nanoparticles on the silicon wafers. An additive containing cyclodextrin and lignosulfonate has been developed in this work. This can remove effectively the saw damage layer and eliminate the white spots and stains on the surface of the silicon wafer. So as to improve the appearance of silicon wafer and make silver nanoparticles uniformly deposited on the surface of the whole silicon wafer. This additive has been proved to be very useful in improving solar cell efficiency, raising parallel resistance and reducing reverse leakage current and so on. Eventually, mass-produced solar cells made by Ag-MACE with this additive have a maximum efficiency of 19.49%, which is 0.46 percent absolutely higher than that without the additive.

In this article, a novel tri-gated hybrid anode AlGaN/GaN power diode (TG-HAD) with intrinsic low turn-on voltage ( ${V}_{\mathrm{\scriptscriptstyle {ON}}}$ ) is demonstrated. A novel forward ${V}_{\mathrm{\scriptscriptstyle {ON}}}$ modulation technique based on an ultrathin barrier (UTB) AlGaN/GaN heterostructure is proposed. ${V}_{\mathrm{\scriptscriptstyle {ON}}}$ of the diode is determined by the intrinsic threshold voltage of the two-dimensional electron gas (2DEG) channel of the UTB heterostructure, which can be precisely controlled and which fundamentally features excellent uniformity by tailoring the AlGaN barrier thickness. On the other hand, compared with the planar GaN diodes, the proposed TG-HAD achieves significant reverse leakage current reduction originating from the effectively suppressed buffer leakage by the tri-gate design. The detailed device characteristics and the underlying mechanisms are investigated by TCAD simulation. The TG-HAD, together with the proposed turn-on voltage modulation technique, is promising for fabricating high performance large periphery devices for power applications.

In this letter, we report on demonstrating a high performance vertical $\beta $ -Ga2O3 Schottky barrier diode (SBD) based on a self-aligned beveled fluorine plasma treatment (BFPT) edge termination structure. Owing to the strong electronegativity of fluorine ions, the fixed negative charges introduced by F ions during self-aligned BFPT process alleviate the electric field crowding, reduce the reverse leakage current and improve the breakdown voltage up to 1 050V even with a low differential on resistance of 2.5 $\text{m}\Omega \cdot $ cm2, combining with a high $I_{\text {on}}/I_{\text {off}}$ of 109, a Schottky barrier height of 1.03 eV and a low ideality factor of 1.07-1.11.Without implantation and post annealing, the self-aligned BFPT can serve as a simple, effective and viable edge termination technique to fabricate high performance $\beta $ -Ga2O3 rectifiers.

High performance NiO/ $\beta $ -Ga2O3 heterojunction pn diodes were realized by applying a sputtered p-type NiO film onto a lightly doped n-type $\beta $ -Ga2O3 epitaxial layer. Taking advantage of the high barrier height against carriers within the pn heterojunction, the demonstrated device exhibited a high breakdown voltage ( ${V}_{B}{)}$ of 1059 V without optimized electric field management techniques, and before breakdown the reverse leakage current density remained below $1~\mu \text{A}$ /cm2. Simultaneously, a relatively low specific on-resistance ( $R_{\text {on, sp}}{)}$ of 3.5 $\text{m}\Omega \cdot \text {cm}^{{2}}$ was achieved. The built-in potential of the heterojunction that determined by a capacitance-voltage ( ${C}$ - ${V}$ ) measurement was around 2.4 eV. As discussed in terms of the energy band diagram of a type-II heterojunction, the conduction band and valence band offsets at the NiO/ $\beta $ -Ga2O3 hetero-interface were estimated to be 1.2 and 2.3 eV, respectively.

We present a model for the vertical conduction through an AlN/p–Si junction, which is used as a base for the growth of GaN power devices. First, we recall that for resistive silicon substrates, the ${I}$ – ${V}$ curves of the AlN/p–Si show a monotonic increase, interrupted by a plateau region. Then, to quantitatively explain this behavior, we propose a novel two-diode model. More specifically, we demonstrate that the AlN/p-Si structure can be split into the series connection of two substructures: 1) an equivalent AlN/n+-Si junction and 2) an equivalent n+-Si/p-Si diode. The n+ layer models the electron inversion layer in the silicon at the interface with the AlN layer. Technology Computer-Aided Design (TCAD) simulations were used to validate these two diode models. By comparing the leakage current of the AlN/p-Si structure with the current through the diodes, we demonstrate that within the plateau region, all the applied voltage drops on the equivalent n+-Si/p-Si junction, and the current through the diodes is limited by the reverse leakage current of the n+-Si/p-Si diode. The plateau ends as soon as impact ionization occurs in the Si substrate, due to the high electric field in the depletion region. After the plateau, the current through the diodes is again limited by charge injection from the inversion layer into the AlN, which occurs through a phonon-assisted tunneling mechanism (possibly trap-assisted).

We present a fully energy-autonomous temperature-to-time converter (TTC) for biomedical applications. This is the first work in literature to power the entire converter purely by a triboelectric energy harvester (TEG). The dynamic leakage suppression full-bridge rectifier (DLS-FBR) reduces reverse leakage current to 1/100, which enables the TEG operated by human motion at $\mu \text{m}$ 1P6M CMOS consumes 0.14 pJ/conversion while powered up purely by a TEG, achieving energy-autonomous operation.

The onset of ion-induced reverse leakage current in SiC Schottky diodes is shown to depend on material properties, ion linear energy transfer (LET), and bias during irradiation, but not the voltage rating of the parts. This is demonstrated experimentally for devices from multiple manufacturers with voltage ratings from 600 to 1700 V. Using a device with a higher breakdown voltage than required in the application does not provide increased robustness related to leakage current degradation, compared to using a device with a lower voltage rating.

Sensitive, high photoresponse and energy-saving detectors are urgently required to monitor solar-blind UV signals. The impressive advantages of Ga2O3 in this field give rise to extensive research and studies. A high-performance dual-mode β-Ga2O3 metal–oxide–semiconductor (MOS)-structured photodiode solar-blind detector is introduced. The device shows a rectifying ratio of 2 × 103 at ±10 V with a low reverse leakage current of 1.05 pA. Under 1.1 μW cm−2 254 nm light illumination, it provides a specific detectivity (D*) of ∼1013 Jones, a high responsivity (R) of 189.89/3.96 A W−1 and a high external quantum efficiency (EQE) of 92 879%/1936% at 10/−10 V, suggesting a high-resolution and sensitive detection in the dual operating (photoconductive/depletion) mode. At zero bias, it exhibits an ultralow dark current of 4.2 pA, an R of 33.48 mA W−1, an EQE of 16.37% and a D* of 1.83 × 1011 Jones, yielding a self-powered operation owing to the enhanced built-in electrical field. Moreover, at ±200 V, the device still avoids breakdown and displays an R of 3930.55 A W−1 and a D* of 1015 Jones, allowing harsh environmental operation. In addition, no obvious degeneration was observed after two months storage. The dual-mode photodiode promises to perform solar-blind detection along with sensitive, stable and self-powered performances.

In this study, the improvement of reverse leakage current characteristics with a sputtered (SP) -AlN buffer layer in GaInN-based green light-emitting diodes (LEDs) has been presented for the first time. To understand the origin of the improvement, a detailed review and careful analysis of reverse leakage current characteristics were performed. The review and analysis identified that the improvement was primarily caused by the suppression of variable-range-hopping process obtained by replacing conventional low-temperature GaN buffer. Verification that threading dislocations and V- defects can enhance the variable-range-hopping process has been received. We believe that this study will contribute to the realization of green LEDs with advantages of high reliability, a long lifetime, and electrical robustness.

This letter reports room-temperature electrically pumped narrow-linewidth GaN-on-Si laser diodes. Unlike conventional distributed Bragg feedback laser diodes with hundreds of gratings, we employed only a few precisely defined slot gratings to narrow the linewidth and mitigate the negative effects of grating fabrication on the device performance. The slot gratings were incorporated into the ridge of conventional Fabry-Pérot cavity laser diodes. A subsequent wet etching in a tetramethyl ammonium hydroxide solution not only effectively removed the damages induced by the dry etching, but also converted the rough and tilted slot sidewalls into smooth and vertical ones. As a result, the threshold current was reduced by over 20%, and the reverse leakage current was decreased by over three orders of magnitude. Therefore, the room-temperature electrically pumped narrow-linewidth GaN-on-Si laser diode has been successfully demonstrated.

In this paper, we carried out a comprehensive study and optimization of implementing p-NiO in the β-Ga2O3 based diodes, including Schottky barrier diode (SBD) with p-NiO guard ring (GR), p-NiO/β-Ga2O3 heterojunction (HJ) barrier Schottky (HJBS) diode, and HJ-PN diode through the TCAD simulation. In particular, we provide design guidelines for future p-NiO-related Ga2O3 diodes with material doping concentrations and dimensions to be taken into account. Although HJ-PN has a ~1 V higher turn-on voltage (Von), its breakdown voltage (BV) is the highest among all diodes. We found that for SBD with p-NiO GRs and HJBS, their forward electrical characteristics and reverse leakage current are related to the total width and the doping concentration of p-NiO, the BV is only related to the doping concentration of p-NiO, and the optimal doping concentration of p-NiO is found to be 4 × 1017 cm−3. Compared with the SBD without p-NiO, the BV of the SBD with p-NiO and HJBS diode can be essentially improved by 3 times. As a result, HJ-PN diode, SBD with p-NiO GRs, and HJ-BS diode achieve a BV/specific on-resistance (Ron,sp) of 5705 V/4.3 mΩ·cm2, 3006 V/3.07 mΩ·cm2, and 3004 V/3.06 mΩ·cm2, respectively. Based on different application requirements, this work provides a useful insight about the diode selection with various structures.

Thin film of Al 2 O 3 was deposited on the p-Si substrate using thermal evaporation method to deposit Al on p-Si. Furthermore, a chemical vapor deposition method (CVD) was used for the oxidation of Al/p-Si in order to synthesize Al 2 O 3 /p-Si structure. The paper is focused on the formation of Al 2 O3, the bands of Al-O and some bands formed with it through growth operation by analyzing spectra of the Fourier transform infrared (FTIR) spectroscopy. The bands of the Al-O were found at the wavenumber 611 cm-1, which indicates that Al 2 O 3 has been formed. Also SiO x band was found at the wavenumber 1000-1100 cm-1, which refers to the construction of a thin interfacial oxide layer between the Si and the Al 2 O 3 layer and other bands. The current-voltage (I-V) characteristics showed that a reverse leakage current was greater than the forward leakage current. The capacitance-voltage (C-V) measurements were also performed on the samples, revealing the improvement of results.

Vertical Pt Schottky contacts to bulk GaN single crystal with an ultrathin Gd2O3 interlayer grown by atomic layer deposition were electrically characterized using temperature dependent current–voltage (I–V–T) and capacitance–voltage (C–V) measurements. The forward I–V characteristics of the Schottky diodes revealed a temperature dependence of barrier height, and were explained by thermionic emission involving barrier inhomogeneity. Based on the thermally activated process, the dominant transport mechanism for reverse leakage current was determined to be Poole–Frenkel emission with the trap energy of 0.78 eV. The flat-band barrier height estimated from C–V method was 1.33 eV. The analysis on C–V data showed very low interface state density, indicating that Gd2O3 is a promising passivation layer in vertical GaN devices.

GaN p-n diodes were formed by selective area regrowth on freestanding GaN substrates using a dry etch, followed by post-etch surface treatment to reduce etch-induced defects, and subsequent regrowth into wells. Etched-and-regrown diodes with a 150 μm diameter achieved 840 V operation at 0.5 A/cm 2 reverse current leakage and a specific on-resistance of 1.2 mΩ·cm 2 . Etched-and-regrown diodes were compared with planar, regrown diodes without etching on the same wafer. Both types of diodes exhibited similar forward and reverse electrical characteristics, which indicate that etch-induced defectivity of the junction was sufficiently mitigated so as not to be the primary cause for leakage. An area dependence for forward and reverse leakage current density was observed, suggesting that the mesa sidewall provided a leakage path.

We have demonstrated AlGaN/GaN high-electron-mobility transistors (HEMTs) fabricated with aMgF2 passivation layer. Upon MgF2 passivation using an e-beam evaporator, the HEMT showed a maximum drain saturation current of 508 mA/mm, a maximum transconductance of 136 mS/mm, a significantly reduced gate forward leakage current, a low gate reverse leakage current of 1.8 × 10−7 A/mm at gate bias voltage of −10 V, and an increased breakdown voltage of 563 V. This suggests that the MgF2 film is quite useful as a passivation layer for AlGaN/GaN HEMTs.

In order to determine the temperature dependence of the reverse transition voltage between thermionic emission and tunneling mechanisms, a numerical method has been applied for β-Ga2O3 Schottky barrier diodes. The main idea of this method is based on the intersection of I–V curves of thermionic emission and tunneling process. The reverse transition voltage increases for low and high temperatures, while it decreases at intermediate temperatures. This means that unexpected peak by Padovani–Stratton’s condition is observed at low temperatures. The reverse transition voltage increases linearly with increasing the barrier height, and the inverse of doping concentration. An analytical model has been proposed to predict the dependence of the reverse transition voltage on temperature, doping concentration and barrier height for β-Ga2O3 Schottky barrier diodes. This model is well tested on experimental reverse transition voltage data previously published in the literature for β-Ga2O3 SBDs.

High-temperature $\beta $ -Ga{2}O{3} Schottky diodes with very low leakage currents, capable of sensitive UVC detection at 350°C, were fabricated on $({\bar{2}}{01})$ -Ga2O3 single crystal substrates using intentionally-oxidized ruthenium (RuOx) Schottky contacts (SCs), with x =~ 2.1. These RuOx: $\beta $ -Ga2O3 SCs were characterized by rectification ratios of more than 1010 at ±3 V and very low reverse leakage current densities of less than 1 nAcm−2 (~1 pA) at −3.0 V, that were unchanged from 24 to 350 °C. These very low high-temperature leakage currents were due to their extremely high Schottky barriers of 2.2 eV at 350°C, that were stable against repeated operation at this temperature. Although not optimized for photodetection, these SCs could detect UVC ( $\lambda = {248}$ nm) radiation at a temperature of 350 °C with a UVC/dark current ratio of ~103. The very high and thermally stable rectifying barriers of these RuOx: $\beta $ -Ga2O3 SCs makes them strong candidates for use in high temperature $\beta $ -Ga2O3 rectifying diodes and UVC photodetectors.

In this letter, we report on demonstrating high-performance lateral GaN Schottky barrier diode (SBD) on silicon substrate with low turn-on voltage ( $\text{V}_{\mathbf {on}}$ ), high breakdown voltage (BV) with low reverse leakage current ( $\text{I}_{\mathbf {R}}$ ), and high power figure of merit (P-FOM) through anode engineering technique. Lateral GaN SBD with anode-cathode distance ( $\text{L}_{\mathbf {AC}}$ ) of $25~\mu \text{m}$ demonstrates a $\text{V}_{\mathbf {on}} =0.38$ V, a BV of >3 kV at a $\text{I}_{\mathbf {R}}$ of $10\mu \text{A}$ /mm and differential specific ON-resistance ( $\text{R}_{\mathbf {on,sp}}$ ) of 2.94 $\text{m}\Omega ~\cdot $ cm2, yielding a high P-FOM of more than 3 GW/cm2. To the best of our knowledge, this P-FOM is the highest value among all the GaN SBDs on any substrates. Combining with 5 A forward current ( $\text{I}_{\mathbf {F}}$ ) and reverse BV >2 kV of a large periphery device with perimeter of 20 mm, GaN SBD with anode engineering technique shows its great promise for next generation power electronics.

In this letter, high-uniformity $8\times 8$ arrays of 4H-SiC ultraviolet (UV) avalanche photodiode (APD) are reported. In order to improve the detectivity, large active area ( $300~\mu \text{m}$ diameter) was designed for APD pixels. Thick SiN x dielectric deposited by plasma enhanced chemical vapor deposition (PECVD) was adopted as insulator and passivation layer to suppress the reverse leakage current and premature breakdown. Despite the large active area, a high yield of 97% is achieved for the pixels in the 4H-SiC APD array. At room temperature, the pixels exhibit a high gain of over 105, a maximum quantum efficiency of larger than 68% @ 282 nm and an excellent UV/visible rejection ratio of 104. In addition, temperature-stable avalanche breakdown voltage with a positive coefficient of 8 mV/°C is obtained. Furthermore, the APD array shows a high uniformity of breakdown voltage with a standard deviation of 0.1 V for all the 64 pixels, and the dark currents at 95% of breakdown voltage are as low as ~1 nA except for two pixels. The performance improvements indicate a new milestone for 4H-SiC APD arrays in UV imaging applications.

We report on record high zero-bias external quantum efficiency (EQE) of 92% for back-illuminated Al0.40Ga0.60N p-i-n ultra-violet (UV) photodetectors on sapphire. The zero-bias responsivity measured 211 mA/W at 289 nm, which is the highest value reported for solar-blind, p-i-n detectors realized over any epitaxial wide band-gap semiconductor. This is also the first report for a p-i-n detector, where a polarization-graded Mg-doped AlGaN layer is utilized as the p-contact layer. The devices exhibited a ten-orders of magnitude rectification, a low reverse leakage current density of 1 nA/cm2 at 10 V, a high $\text{R}_{{0}}\text{A}$ product of $1.3\times 10^{{11}} \Omega $ .cm2 and supported fields exceeding 5 MV/cm. The light-to-dark current ratio and the UV-to-visible rejection ratio for the detectors exceeded six-orders of magnitude and the thermal noise limited detectivity (D*) measured $6.1\times 10^{{14}}$ cmHz1/2W−1. The state-of-the-art performance parameters can be attributed to a high crystalline quality absorbing AlGaN epi-layer resulting from the use of an AlN/AlGaN superlattice buffer and an improved p-contact via polarization grading.

Lead-free undoped and Vanadium (V) doped Zinc Oxide (ZnO) nanorods were grown on rigid Fluorine-doped Tin Oxide substrates using a simple hydrothermal method. Poly(3,4-ethylenedioxythiophene) polystyrene sulfonate was coated on the grown nanorods to form a p-n junction. The optical, crystalline and morphological analysis were done using X-ray diffraction, Ultraviolet-Visible spectroscopy, Field Emission Scanning Electron Microscope and Spectrofluorescence. The decrease in bandgap from 3.1 eV (undoped) to 3 eV (V doped) showed increased conductivity. Current-Voltage analysis depicted an improvement in the electrical properties of V doped device in terms of a low turn-on voltage, rectification ratio and reverse leakage current density. The RC time constant was analyzed using Impedance analysis. A decrease in RC time constant value and internal resistance of 0.06 msec and 1.61 kΩ respectively for V doped ZnO device compared with undoped one showed an improved piezoelectric property. The maximum output voltages of 1.6 V and 1.9 V for 9 Hz and 1 g input respectively were observed in the V doped device. The sensitivity of undoped and V doped device was 1.71 V/g and 1.93 V/g respectively. It is evident that ~12.9% of improved sensitivity is obtained when V is doped into ZnO nanorods.

In this paper, the reliability of quasi-vertical GaN Schottky barrier diodes under high temperature reverse bias (HTRB) stress has been investigated. The test results indicate that the stress applied on the devices makes reverse leakage current decrease, but the forward performance, capacitance and reverse recovery performance show negligible changes. With the help of experiments and T-CAD simulations, it is demonstrated that there is trapping process of hot electrons along vertical sidewall of the device under high reverse voltage stress, which leads to the decrease of reverse leakage current. An empirical model can be used to predict the variations and good coincidences can be observed based on the acquired experiment data. Moreover, long time over voltage stress on the device leads to the direct failure. By using the infrared thermography analysis and T-CAD simulations, the failure mechanism has been also illustrated.

AlGaN-based deep ultraviolet flip-chip light-emitting diodes (DUV-FCLEDs), have been fabricated by different doping processes in n-AlGaN epilayers, respectively. That is, the silicon uniformly doped (Si-UD) processes and the modulation doped (MD) growth methods. Compared with the UD sample of about 278-nm emission wavelength, the electrical structures, optical properties and output performance of the MD sample, have been effectively enhanced. The MD sample is a more intense UV emitter than the UD sample by a factor of about 30% in the electroluminescence intensities, the photoluminescence spectra also demonstrate that the MD methods can effectively enhance the light emissions. The measured peak capacitance of internal capacitance–voltage characteristics in the UD sample is only 175 pF at room temperature, while the MD sample is about 390 pF, which is mostly attributed to the series capacitors effects within the periodic n-AlGaN super-lattices structures. Both the forward bias voltage and reverse leakage current of the MD sample are directly reduced than those of the UD sample, and the calculated conductance is significantly increased. We demonstrate that there are higher current spreading efficiency and better devices’ reliability in the MD sample with the Si-MD processes. Our investigations may be useful for the enhancements of structure and optoelectronic performance in DUV-FCLEDs succeeding the MD methods in n-AlGaN epi-layers.

Dislocations originating from the seed junctions are the most harmful defects in quasi-single crystalline silicon (QSC-Si). In traditional -oriented QSC-Si ingots, dislocations easily develop into cascade shape, or even further form sub-grain boundaries as the ingot grows. In this paper, we have developed a novel -oriented QSC-Si ingot to control the gliding and propagation of dislocations. It is found that the cascade shape is absent and dislocations only aggregate in the {100}/{100} boundary planes of -oriented seeds, revealed by the minority carrier lifetime mapping and photoluminescence image. Accordingly, the internal quantum efficiency of -oriented QSC-Si solar cells is obviously higher than that of the traditional -oriented ones. Nevertheless, it should be noticed that the average photoelectric conversion efficiency of -oriented QSC-Si solar cells could be 0.6% lower than that of traditional ones if the {100}/{100} boundary is included in the solar cell, due to a higher reverse leakage current. This problem can be involved by enlarging the size of seed crystals or adopting better seed arrangement. These results provide a new promising method for the development of high quality QSC-Si in photovoltaic industry.

Nickel nitride (NixN) films were deposited by magnetron reactive sputtering under varying N2 partial pressure (P(N2)) conditions range from 0.005 to 0.184 Pa. With the increasing P(N2), the deposition rate decreased while the resistivity and root mean square roughness increased. X-ray diffraction (XRD) and X-ray photoelectron spectra (XPS) indicate that Ni4N and Ni3N phases dominate the films at low and medium P(N2), respectively. In addition, Ni2N phase can be also obtained at high P(N2). The Ni/N ratio evaluated from the energy dispersive X-ray spectrum is consistent with the NixN phases showed in the XRD spectra of different P(N2). Compared with the GaN diodes with Ni anode, the Schottky barrier height and turn-on voltage of the Schottky barrier diodes with NixN anode were increased by 0.03–0.18 eV and 0.03–0.15 V, respectively. Capacitance-voltage curves demonstrated that good interface quality with no obvious hysteresis was realized. Ni3N anode diodes obtained at medium P(N2) possess a high barrier height and a low reverse leakage current are regarded as a promising anode material.

Vertical c-plane GaN p–n diodes, where the p-GaN layer is formed by epitaxial regrowth using metal–organic chemical-vapor deposition, are reported. Current–voltage (I–V) performance similar to continuously grown p–n diodes is demonstrated, including low reverse leakage current and reverse breakdown voltage in excess of −600 V, despite the lack of field management structures to increase the reverse breakdown voltage. Secondary-ion mass spectrometry analysis of regrown interfaces reveals that the primary source of Si at the regrown interface (“Si spike”) is ex situ contamination during wafer handling prior to loading for regrowth. Continuously grown p–n diodes with intentional Si doping at the p–n junction do not show degraded I–V performance for Si sheet concentrations