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Showing papers on "Diode published in 2021"


Journal ArticleDOI
TL;DR: In this article, a fluorine post-synthesis treatment was applied to perovskite nanostructures to achieve a temperature independent emission efficiency of near unity and constant decay kinetics up to a temperature of 373 K.
Abstract: The thermal quenching of light emission is a critical bottleneck that hampers the real-world application of lead halide perovskite nanocrystals in both electroluminescent and down-conversion light-emitting diodes. Here, we report CsPbBr3 perovskite nanocrystals with a temperature-independent emission efficiency of near unity and constant decay kinetics up to a temperature of 373 K. This unprecedented regime is obtained by a fluoride post-synthesis treatment that produces fluorine-rich surfaces with a wider energy gap than the inner nanocrystal core, yielding suppressed carrier trapping, improved thermal stability and efficient charge injection. Light-emitting diodes incorporating these fluoride-treated perovskite nanocrystals show a low turn-on voltage and spectrally pure green electroluminescence with an external quantum efficiency as high as 19.3% at 350 cd m−2. Importantly, nearly 80% of the room-temperature external quantum efficiency is preserved at 343 K, in contrast to the dramatic drop commonly observed for standard CsPbBr3 perovskite nanocrystal light-emitting diodes. These results provide a promising pathway for high-performance, practical light-emitting diodes based on perovskite nanostructures. Fluoride-treated CsPbBr3 nanocrystals emit light with near unity efficiency at temperatures of up to 373 K.

193 citations


Journal ArticleDOI
TL;DR: In this article, a high performance NiO/β-Ga2O3 pn heterojunction diode with an optimized interface by annealing is presented, which leads to a record high power figure of merit of 0.65 GW/cm2.
Abstract: In this Letter, we report a high-performance NiO/β-Ga2O3 pn heterojunction diode with an optimized interface by annealing. The electrical characteristics of the pn diode without annealing (PND) and with annealing (APND) are studied systematically. The APND device has a lower specific on-resistance of 4.1 mΩ cm2, compared to that of the PND, 5.4 mΩ cm2. Moreover, for the APND, a high breakdown voltage of 1630 V with lower leakage current is achieved, which is 730 V higher than that of the PND. The enhanced electrical performance of the APND leads to a record high power figure of merit of 0.65 GW/cm2 in Ga2O3-based pn diodes, which is among the best reported results in Ga2O3 power devices. In addition, the interface trap density of the diode decreases from 1.04 × 1012 to 1.33 × 1011 eV−1 cm−2 after annealing, contributing to much lower hysteresis. Simultaneously, the ideality factor n for the APND is steady at elevated temperatures due to the stable interface. The results of C − V characteristics reveal the bulk defects inside the nickel oxide film grown by sputtering, which are calculated by high- and low-frequency capacitance methods. X-ray photoelectron spectroscopy of NiO illustrates the reasons for the changes in the concentration of holes and defects in the film before and after annealing. This work paves the way for further improving the performance of Ga2O3 diode via interface engineering.

81 citations



Journal ArticleDOI
TL;DR: By using density functional theory and ab initio quantum-transport simulation, Wang et al. as discussed by the authors studied the Schottky barrier and the rectifying behavior of diodes consisting of the two-dimensional metal phase $1T\text{\ensuremath{-}}{\mathrm{MoS}}_{2}$ and semiconductor phase 2H-${ MoS}}
Abstract: By using density functional theory and ab initio quantum-transport simulation, we study the Schottky barrier and the rectifying behavior of diodes consisting of the two-dimensional metal phase $1T\text{\ensuremath{-}}{\mathrm{MoS}}_{2}$ and semiconductor phase 2H-${\mathrm{MoS}}_{2}$. The results show that the Schottky barrier of the out-of-plane (OP) contacted ${\mathrm{MoS}}_{2}$ heterostructure diode is a little different from that of the in-plane (IP) contacted ${\mathrm{MoS}}_{2}$ heterostructure diode. The current-voltage characteristics show that the OP diode has the better rectifying behavior compared to the IP diode under the zero gate voltage. The corresponding maximum rectifier ratio of the OP Schottky barrier diode is close to ${10}^{7}$ at 0.9 V bias voltage. More interestingly, we find that the gate voltage can be used to effectively control the rectifying behavior of the two diodes. The positive gate voltages can increase the current value of two Schottky barrier diodes, but weaken their rectification ratios. The negative gate voltages can reverse the rectifying direction of two Schottky barrier diodes. The above results provide good theoretical guidance for the designing of diode devices based on two-dimensional materials in the future.

79 citations


Journal ArticleDOI
TL;DR: In this article, the authors demonstrate the first vertical β-Ga2O3 junction barrier Schottky (JBS) diode with the implementation of thermally oxidized p-type NiO to compensate for the dilemma of the forfeit of the p-Type β-GAspO3.
Abstract: In this article, we report on demonstrating the first vertical β-Ga2O3 junction barrier Schottky (JBS) diode with the implementation of thermally oxidized p-type NiO to compensate for the dilemma of the forfeit of the p-type β-Ga2O3. With this wide-bandgap p-type NiOx, β-Ga2O3 JBS diodes with an area of 100 × 100 μ m2 achieve a breakdown voltage (BV) and specific on -resistance R on,sp of 1715 V and 3.45 mΩ·cm2, respectively, yielding a Baliga's figure of merit (FOM) of BV2/ R on,sp = 0.85 GW/cm2, which is the highest direct-current FOM value among all β-Ga2O3 diodes. Meanwhile, a large size JBS diode with the area of 1 × 1 mm2 shows a forward current IF and BV of 5 A/700 V, which is also the best IF and BV combinations (FOM = 64 MW/cm2) among all published results about large-area Ga2O3 diodes. Dynamic switching characteristics reveal that the diode suffers from a negligible current collapse phenomenon even at a −600 V and 103 s stress, showing the great promise of implementing p-NiO in the future β-Ga2O3 power electronic devices.

69 citations


Journal ArticleDOI
TL;DR: In this paper, a better tradeoff between fast reverse-recovery and rugged surge-current capability has been demonstrated in NiO/Ga2O3 p-n heterojunction diodes (HJDs).
Abstract: Ga2O3 power diodes with high voltage/current ratings, superior dynamic performance, robust reliability, and potentially easy-to-implement are a vital milestone on the Ga2O3 power electronics roadmap. In this letter, a better tradeoff between fast reverse-recovery and rugged surge-current capability has been demonstrated in NiO/Ga2O3 p-n heterojunction diodes (HJDs). With the double-layered p-NiO design, the HJD exhibits superior electrostatic performances, including a high breakdown voltage of 1.37 kV, a forward current of 12.0 A with a low on-state resistance of 0.26 Ω, yielding a static Baliga's figure of merit (FOM) of 0.72 GW/cm2. Meanwhile, the fast switching performance has been observed with a short reverse recovery time in nanosecond timescale (11 ns) under extreme switching conditions of d i /d t up to 500 A/μs. In particular, for a 9-mm2 HJD, a large surge current of 45 A has also been obtained in a 10-ms surge transient, thanks to the conductivity modulation effect. These results are comparable with those of the advanced commercial SiC SBDs and have significantly outperformed the past reported Ga2O3 HJDs, fulfilling the enormous potential of Ga2O3 in power applications.

68 citations


Journal ArticleDOI
TL;DR: In this article, the authors summarized both theoretical and experimental studies of various types of thermal diodes introduced in recent years and classified them based on their primary heat transfer mechanisms and the materials from which they are constructed.

61 citations


Journal ArticleDOI
TL;DR: In this article, a dual-band and polarization-angle-independent rectifying metasurface (MS) with a miniaturized dimension and a wide incident angle range is presented.
Abstract: A dual-band and polarization-angle-independent rectifying metasurface (MS) with a miniaturized dimension and a wide incident angle range are presented in this article. The proposed structure consists of a single layer of periodic cell arrays with integrated diodes, a $dc$ feed, and a load. A novel method of incorporating surface-mount components (e.g., diodes) into the texture is developed to simplify the structure. The matching network between MS and the nonlinear rectifier can be eliminated directly due to the multimode resonance and adjustable high-impedance characteristics of the MS. Moreover, the proposed MS can maintain high conversion efficiency by using different diodes without changing the overall topology. In addition, the proposed design can effectively capture incoming waves with arbitrary polarizations and a wide incident angle range of 60°. The $4\times 4$ MS array is fabricated and measured. Experimental results show that the proposed structure can achieve maximum efficiency of 58% at 2.4 GHz and 50% at 5.8 GHz with an input power of 0 dBm under different polarizations and incident angles. Importantly, it is also shown that the rectifying MS can maintain high efficiency over a wide power range from −3 to 10 dBm. The proposed design concept is very suitable for the adaptive wireless power supply of portable devices.

54 citations


Journal ArticleDOI
TL;DR: In this paper, a β-Ga2O3 HJBS diode with p-type NiOx was shown to achieve a low specific on-resistance (Ron,sp) of 1.94 mΩ cm2 with a breakdown voltage 1.34
Abstract: In this paper, we show that high-performance β-Ga2O3 hetero-junction barrier Schottky (HJBS) diodes with various β-Ga2O3 periodic fin widths of 1.5/3/5 μm are demonstrated with the incorporation of p-type NiOx. The β-Ga2O3 HJBS diode achieves a low specific on-resistance (Ron,sp) of 1.94 mΩ cm2 with a breakdown voltage of 1.34 kV at a β-Ga2O3 periodic fin width of 3 μm, translating to a direct-current Baliga's power figure of merit (PFOM) of 0.93 GW/cm2. In addition, we find that by shrinking the β-Ga2O3 width, the reverse leakage current is minimized due to the enhanced sidewall depletion effect from p-type NiOx. β-Ga2O3 HJBS diodes with p-type NiOx turn out to be an effective route for Ga2O3 power device technology by considering the high PFOM while maintaining a suppressed reverse leakage current.

53 citations


Journal ArticleDOI
TL;DR: In this article, an intrinsically stretchable organic light-emitting diode, whose constituent materials are all highly stretchable, was presented, whose turn-on voltage is as low as 8 V and the maximum luminance, which is a summation of the luminance values from both the anode and cathode sides, is 4400 cd m-2.
Abstract: Soft and conformable optoelectronic devices for wearable and implantable electronics require mechanical stretchability. However, very few researches have been done for intrinsically stretchable light-emitting diodes. Here, we present an intrinsically stretchable organic light-emitting diode, whose constituent materials are all highly stretchable. The resulting intrinsically stretchable organic light-emitting diode can emit light when exposed to strains as large as 80%. The turn-on voltage is as low as 8 V, and the maximum luminance, which is a summation of the luminance values from both the anode and cathode sides, is 4400 cd m-2 It can also survive repeated stretching cycles up to 200 times, and small stretching to 50% is shown to substantially enhance its light-emitting efficiency.

53 citations


Journal ArticleDOI
TL;DR: In this article, the authors present the first experimental demonstrations of large-area Ga2O3 Schottky barrier diodes (SBDs) packaged in the bottom-side-cooling and double-sidecooling configurations, and for the first time, characterizes the surge current capabilities of these packaged SBDs.
Abstract: Ultrawide-bandgap gallium oxide (Ga2O3) devices have recently emerged as promising candidates for power electronics; however, the low thermal conductivity ( k T) of Ga2O3 causes serious concerns about their electrothermal ruggedness. This letter presents the first experimental demonstrations of large-area Ga2O3 Schottky barrier diodes (SBDs) packaged in the bottom-side-cooling and double-side-cooling configurations, and for the first time, characterizes the surge current capabilities of these packaged Ga2O3 SBDs. Contrary to popular belief, Ga2O3 SBDs with proper packaging show high surge current capabilities. The double-side-cooled Ga2O3 SBDs with a 3 × 3-mm2 Schottky contact area can sustain a peak surge current over 60 A, with a ratio between the peak surge current and the rated current superior to that of similarly-rated commercial SiC SBDs. The key enabling mechanisms for this high surge current are the small temperature dependence of on -resistance, which strongly reduces the thermal runaway, and the double-side-cooled packaging, in which the heat is extracted directly from the Schottky junction and does not need to go through the low- k T bulk Ga2O3 chip. These results remove some crucial concerns regarding the electrothermal ruggedness of Ga2O3 power devices and manifest the significance of their die-level thermal management.

Journal ArticleDOI
TL;DR: In this article, high performance β-Ga2O3 vertical heterojunction barrier Schottky (HJBS) diodes have been demonstrated together with the investigation of reverse leakage mechanisms.
Abstract: In this Letter, high-performance β-Ga2O3 vertical heterojunction barrier Schottky (HJBS) diodes have been demonstrated together with the investigation of reverse leakage mechanisms. In HJBS configurations, NiO/β-Ga2O3 p-n heterojunctions and p-NiO field limiting rings (FLRs) are implemented by using a reactive sputtering technique at room temperature without intentional etching damages. Determined from the temperature-dependent current-voltage characteristics, the reverse leakage mechanism of the HJBS diode is identified to be Poole-Frenkel emission through localized trap sates with an energy level of EC-0.72 eV. With an uniform FLR width/spacing of 2 μm in HJBS, a maximum breakdown voltage (BV) of 1.89 kV and a specific on-resistance (Ron,sp) of 7.7 mΩ·cm2 are achieved, yielding a high Baliga's figure-of-merit (FOM, BV2/Ron,sp) of 0.46 GW/cm2. The electric field simulation and statistical experimental facts indicate that the electric field crowding effect at device edges is greatly suppressed by the shrinkage of p-NiO FLR spacing, and the capability of sustaining high BV is enhanced by the NiO/β-Ga2O3 bipolar structure, both of which contribute to the improved device performance. This work makes a significant step to achieve high performance β-Ga2O3 power devices by implementing alternative bipolar structures to overcome the difficulty in p-type β-Ga2O3.

Journal ArticleDOI
TL;DR: In this article, a reverse-biased homoepitaxial GaN p-n junction diode was experimentally investigated at 223-373 K by novel photomultiplication measurements utilizing above-and below-bandgap illumination.
Abstract: Avalanche multiplication characteristics in a reverse-biased homoepitaxial GaN p–n junction diode are experimentally investigated at 223–373 K by novel photomultiplication measurements utilizing above- and below-bandgap illumination. The device has a non-punch-through one-side abrupt p–-n+ junction structure, in which the depletion layer mainly extends to the p-type region. For above-bandgap illumination, the light is absorbed at the surface p+-layer, and the generated electrons diffuse and reach the depletion layer, resulting in an electron-injected photocurrent. On the other hand, for below-bandgap illumination, the light penetrates a GaN layer and is absorbed owing to the Franz–Keldysh effect in the high electric field region (near the p–n junction interface), resulting in a hole-induced photocurrent. The theoretical (non-multiplicated) photocurrents are calculated elaborately, and the electron- and hole-initiated multiplication factors are extracted as ratios of the experimental data to the calculated values. Through the mathematical analyses of the multiplication factors, the temperature dependences of the impact ionization coefficients of electrons and holes in GaN are extracted and formulated by the Okuto–Crowell model. The ideal breakdown voltage and the critical electric field for GaN p–n junctions of varying doping concentration are simulated using the obtained impact ionization coefficients, and their temperature dependence and conduction-type dependence were discussed. The simulated breakdown characteristics show good agreement with data reported previously, suggesting the high accuracy of the impact ionization coefficients obtained in this study.

Journal ArticleDOI
TL;DR: In this article, the avalanche and surge current ruggedness of the industry's first 1.2kV-class vertical GaN p-n diodes fabricated on 100mm GaN substrates was reported.
Abstract: This letter reports the avalanche and surge current ruggedness of the industry's first 1.2-kV-class vertical GaN p-n diodes fabricated on 100-mm GaN substrates. The 1.2-kV vertical GaN p-n diodes with a 1.39-mm2 device area and an avalanche breakdown voltage of 1589 V show a critical avalanche energy density of 7.6 J/cm2 in unclamped inductive switching tests, as well as a critical surge current of 54 A and a critical surge energy density of 180 J/cm2 in 10-ms surge current tests. All these values are the highest reported in vertical GaN devices and comparable to those of commercial SiC p-n diodes and merged p-n Schottky diodes. These GaN p-n diodes show significantly smaller reverse recovery compared to SiC p-n diodes, revealing less conductivity modulation in n-GaN. The negative temperature coefficient of differential on-resistance and the anticlockwise surge I–V locus are believed to be due to the increased acceptor ionization in p-GaN and the decreased contact resistance at high temperatures. These results suggest a high ruggedness of GaN p-n junctions with small bipolar currents and fast switching capabilities. As the first electrothermal ruggedness data for industry's vertical GaN devices, these results provide key new insights for the development of vertical GaN devices as well as their application spaces.

Journal ArticleDOI
15 Feb 2021-ACS Nano
TL;DR: In this paper, the authors demonstrate a lateral p-type/intrinsic/n-type (p-i-n) homojunction based multilayer WSe2 diode.
Abstract: High-quality homogeneous junctions are of great significance for developing transition metal dichalcogenides (TMDs) based electronic and optoelectronic devices. Here, we demonstrate a lateral p-type/intrinsic/n-type (p-i-n) homojunction based multilayer WSe2 diode. The photodiode is formed through selective doping, more specifically by utilizing self-aligning surface plasma treatment at the contact regions, while keeping the WSe2 channel intrinsic. Electrical measurements of such a diode reveal an ideal rectifying behavior with a current on/off ratio as high as 1.2 × 106 and an ideality factor of 1.14. While operating in the photovoltaic mode, the diode presents an excellent photodetecting performance under 450 nm light illumination, including an open-circuit voltage of 340 mV, a responsivity of 0.1 A W-1, and a specific detectivity of 2.2 × 1013 Jones. Furthermore, benefiting from the lateral p-i-n configuration, the slow photoresponse dynamics including the photocarrier diffusion in undepleted regions and photocarrier trapping/detrapping due to dopants or doping process induced defect states are significantly suppressed. Consequently, a record-breaking response time of 264 ns and a 3 dB bandwidth of 1.9 MHz are realized, compared with the previously reported TMDs based photodetectors. The above-mentioned desirable properties, together with CMOS compatible processes, make this WSe2p-i-n junction diode promising for future applications in self-powered high-frequency weak signal photodetection.

Journal ArticleDOI
16 Feb 2021-Sensors
TL;DR: In this paper, the authors reviewed the recent progress in resonant-tunneling diode (RTD) THz oscillators, which are compact semiconductor THz sources, including principles and characteristics of oscillation, studies addressing high frequency and high output power, a structure which can easily be fabricated, frequency tuning, spectral narrowing, different polarizations, and select applications.
Abstract: A compact source is important for various applications utilizing terahertz (THz) waves. In this paper, the recent progress in resonant-tunneling diode (RTD) THz oscillators, which are compact semiconductor THz sources, is reviewed, including principles and characteristics of oscillation, studies addressing high-frequency and high output power, a structure which can easily be fabricated, frequency tuning, spectral narrowing, different polarizations, and select applications. At present, fundamental oscillation up to 1.98 THz and output power of 0.7 mW at 1 THz by a large-scale array have been reported. For high-frequency and high output power, structures integrated with cylindrical and rectangular cavities have been proposed. Using oscillators integrated with varactor diodes and their arrays, wide electrical tuning of 400-900 GHz has been demonstrated. For spectral narrowing, a line width as narrow as 1 Hz has been obtained, through use of a phase-locked loop system with a frequency-tunable oscillator. Basic research for various applications-including imaging, spectroscopy, high-capacity wireless communication, and radar systems-of RTD oscillators has been carried out. Some recent results relating to these applications are discussed.

Journal ArticleDOI
TL;DR: In this paper, a low triplet energy hole transporting interlayer with high mobility was designed for blue TADF-OLEDs with below bandgap electroluminescence.
Abstract: Blue organic light-emitting diodes require high triplet interlayer materials, which induce large energetic barriers at the interfaces resulting in high device voltages and reduced efficiencies. Here, we alleviate this issue by designing a low triplet energy hole transporting interlayer with high mobility, combined with an interface exciplex that confines excitons at the emissive layer/electron transporting material interface. As a result, blue thermally activated delay fluorescent organic light-emitting diodes with a below-bandgap turn-on voltage of 2.5 V and an external quantum efficiency (EQE) of 41.2% were successfully fabricated. These devices also showed suppressed efficiency roll-off maintaining an EQE of 34.8% at 1000 cd m−2. Our approach paves the way for further progress through exploring alternative device engineering approaches instead of only focusing on the demanding synthesis of organic compounds with complex structures. Thermally activated delayed fluorescence organic light-emitting diodes (TADF-OLEDs) rely on high triplet energy interlayers to confine excitons, which results in reduced performance. Here, the authors report high-performance blue TADF-OLEDs with below bandgap electroluminescence.

Journal ArticleDOI
TL;DR: In this article, a multi-color phosphor-in-glass (PiG) was successfully fabricated by a single-step co-sintering strategy at a relative low temperature (850°C).

Journal ArticleDOI
11 May 2021
TL;DR: Hybridized local and charge transfer (HLCT) excited state fluorophores as discussed by the authors enable full exciton utilization through a reverse intersystem crossing from high-lying triplet states to singlet state.
Abstract: Hybridized local and charge-transfer (HLCT) excited-state fluorophores, which enable full exciton utilization through a reverse intersystem crossing from high-lying triplet states to singlet state,

Journal ArticleDOI
Zhengyi Yang1, Na Kou1, Shixing Yu1, Fei Long1, Lili Yuan1, Zhao Ding1, Zhengping Zhang1 
TL;DR: In this paper, a reconfigurable polarization conversion method based on a metasurface turned by PIN diodes is proposed, which consists of one layer of a dielectric and two layers of metal surfaces.
Abstract: A novel reconfigurable polarization conversion method based on a metasurface turned by PIN diodes is proposed herein. The proposed metasurface consists of one layer of a dielectric and two layers of metal surfaces. When the diode is in an OFF-state, a wideband linear to circular (LTC) polarization converter is realized. The results show that the metasurface can achieve LTC polarization conversion in the frequency range of 11.8–24.1 GHz, and the axial ratio (AR) reveals that the 3-dB bandwidth is approximately 68.5%. When the diode is in the ON-state, a dual-band linear to linear (LTL) polarization converter is realized, with the 3-dB bandwidths of 10.5–13.9 GHz and 17.7–27.2 GHz, achieving a polarization converter ratio (PCR) greater than 90%. The dc bias circuit of the PIN diode is etched on the reflectance surface. Therefore, no additional feeding lines are introduced, which can decrease the impact on the active metasurface; this metasurface has practical applications in microwave communication systems.

Journal ArticleDOI
TL;DR: In this article, a quasi-vertical GaN junction barrier Schottky diode on a low-cost sapphire substrate was reported, achieving a reverse leakage in level of 10−7 A/cm2, as well as a high on/off current ratio of 1010 and a high breakdown voltage of 838 V.
Abstract: In this letter, we report a quasi-vertical GaN junction barrier Schottky diode on low-cost sapphire substrate. With the high quality GaN epitaxy and selective-area p-islands formed via Magnesium ion implantation at the anode region, reverse leakage in level of 10−7 A/cm2 was achieved, as well as a high on/off current ratio of 1010 and a high breakdown voltage of 838 V. Meanwhile, advantageous characteristics as expected in vertical GaN Schottky barrier diode were realized, including a low turn-on voltage of 0.5 V and fast switching performance under 400 V/10 A operation condition. Along with the improved heat dissipation via substrate thinning and packaging techniques, the diode retains a relatively low thermal resistance, enabling high current rectification level over 60 A, power efficiency up to 98.7 %, while maintaining low case temperatures.

Journal ArticleDOI
TL;DR: In this article, the authors summarized the latest research progress in aluminum nitride (AlN) crystals grown by the physical vapor transport (PVT) method in recent years, and introduced their applications in deep UV-LEDs, UV lasers and Schottky barrier diodes (SBDs).
Abstract: In recent years, ultrawide bandgap semiconductor materials represented by aluminum nitride (AlN) have attracted worldwide attention due to their excellent high-frequency power characteristics, stable high-temperature performance, low energy loss, and good ultraviolet (UV) transmittance. They have great application prospects in the fields of high-efficiency optoelectronic devices, high-power and high-frequency electronic devices, ultra-high voltage power electronic devices, deep UV warning and guidance, and deep UV-LED disinfection. The physical vapor transport (PVT) method has the advantages of a simple growth process, fast growth rate, and high crystal integrity, and has gradually become one of the most effective methods for growing bulk AlN crystals. This review systematically summarizes the latest research progress in AlN crystals grown by the PVT method in recent years, and introduces their applications in deep UV-LEDs, UV lasers and Schottky barrier diodes (SBDs). Finally, the challenges and application prospects of AlN crystals are discussed. As an important new type of direct bandgap ultrawide bandgap semiconductor material, AlN crystals have shown extremely important strategic application value. The output power of deep UV-LED devices meets practical requirements, and high-power electronic power devices are still in the verification stage. From the perspective of material superiority, they have considerable development potential.

Journal ArticleDOI
TL;DR: In this paper, a single equation is proposed to describe the currentvoltage characteristics of two-terminal semiconductor devices with Schottky contacts, which can be used to estimate the Schotty barrier height and the ideality factor.
Abstract: Schottky barriers are often formed at the semiconductor/metal contacts and affect the electrical behaviour of semiconductor devices. In particular, Schottky barriers have been playing a major role in the investigation of the electrical properties of mono and two-dimensional nanostructured materials, although their impact on the current-voltage characteristics has been frequently neglected or misunderstood. In this work, we propose a single equation to describe the current-voltage characteristics of two-terminal semiconductor devices with Schottky contacts. We apply the equation to numerically simulate the electrical behaviour for both ideal and non-ideal Schottky barriers. The proposed model can be used to directly estimate the Schottky barrier height and the ideality factor. We apply it to perfectly reproduce the experimental current-voltage characteristics of ultrathin molybdenum disulphide or tungsten diselenide nanosheets and tungsten disulphide nanotubes. The model constitutes a useful tool for the analysis and the extraction of relevant transport parameters in any two-terminal device with Schottky contacts.

Journal ArticleDOI
TL;DR: In this article, the authors demonstrate a superconducting diode achieved in a conventional Superconducting film patterned with a conformal array of nanoscale holes, which breaks the spatial inversion symmetry.
Abstract: A superconducting diode is an electronic device that conducts supercurrent and exhibits zero resistance primarily for one direction of applied current. Such a dissipationless diode is a desirable unit for constructing electronic circuits with ultralow power consumption. However, realizing a superconducting diode is fundamentally and technologically challenging, as it usually requires a material structure without a centre of inversion, which is scarce among superconducting materials. Here, we demonstrate a superconducting diode achieved in a conventional superconducting film patterned with a conformal array of nanoscale holes, which breaks the spatial inversion symmetry. We showcase the superconducting diode effect through switchable and reversible rectification signals, which can be three orders of magnitude larger than that from a flux-quantum diode. The introduction of conformal potential landscapes for creating a superconducting diode is thereby proven as a convenient, tunable, yet vastly advantageous tool for superconducting electronics. This could be readily applicable to any superconducting materials, including cuprates and iron-based superconductors that have higher transition temperatures and are desirable in device applications. A superconducting diode is dissipationless and desirable for electronic circuits with ultralow power consumption, yet it remains challenging to realize it. Here, the authors achieve a superconducting diode in a conventional superconducting film patterned with a conformal array of nanoscale holes.

Journal ArticleDOI
TL;DR: In this article, a back-end-of-line (BEOL), complementary metal-oxide-semiconductor (CMOS)-compatible Al0.64Sc0.36N-based ferroelectric diode that shows polarization-dependent hysteresis in its leakage currents is presented.
Abstract: In this Letter, we report a back-end-of-line (BEOL), complementary metal–oxide–semiconductor (CMOS)-compatible Al0.64Sc0.36N-based ferroelectric diode that shows polarization-dependent hysteresis in its leakage currents. Our device comprises a metal/insulator/ferroelectric/metal structure (Pt/native oxide/Al0.64Sc0.36N/Pt) that is compatible with BEOL temperatures (≤ 350 °C) grown on top of a 4-in. silicon wafer. The device shows self-selective behavior as a diode with > 105 rectification ratio (for 5 V). It can suppress sneak currents without the need for additional access transistors or selectors. Furthermore, given the polarization-dependent leakage, the diode current–voltage sweeps are analogous to that of a memristor with an on/off ratio of ∼ 50 000 between low and high resistance states. Our devices also exhibit stable programed resistance states during DC cycling and a retention time longer than 1000 s at 300 K. These results demonstrate that this system has significant potential as a future high-performance post-CMOS compatible nonvolatile memory technology.

Journal ArticleDOI
TL;DR: In this article, a multi-layer perceptron, a feed-forward back-propagation artificial neural network was developed using 362 experimental data obtained, where temperature (T) and voltage (V) values were selected as input variables and the hidden layer has 15 neurons, the current (I) value was obtained as output.
Abstract: Shottky diodes are one of the important components of electronic systems. Therefore, it is very important to determine the parameters of the diodes according to the area in which they will be used. One of the most important of these parameters is the current-voltage characteristic of the diode. In this study, firstly, current values of the Schottky diode in the voltage range of −2 V to +3 V are experimentally measured in the temperature range of 100–300 K. In order to estimate the current-voltage characteristic of Shottky diode at different temperatures, a multi-layer perceptron, a feed-forward back-propagation artificial neural network was developed using 362 experimental data obtained. In the artificial neural network where temperature (T) and voltage (V) values are selected as input variables and the hidden layer has 15 neurons, the current (I) value is obtained as output. The results obtained from the artificial neural network have been found to be in good agreement with the experimental data of the Schottky diode.

Journal ArticleDOI
TL;DR: In this article, the authors demonstrate scaled-up GaN-on-Si tri-Anode Schottky barrier diodes (SBDs), whose excellent dc and switching performance are compared to commercial Si fast-recovery dioders and SiC SBDs.
Abstract: Gallium nitride (GaN) transistors are being employed in an increasing number of applications thanks to their excellent performance and competitive price. Yet, GaN diodes are not commercially available, and little is known about their performance and potential impact on power circuit design. In this article, we demonstrate scaled-up GaN-on-Si Tri-Anode Schottky barrier diodes (SBDs), whose excellent dc and switching performance are compared to commercial Si fast-recovery diodes and SiC SBDs. Moreover, the advantageous lateral GaN-on-Si architecture enables the integration of several devices on the same chip, paving the way for power integrated circuits (ICs). This is demonstrated by realizing a diode-multiplier IC, which includes up to eight monolithically integrated SBDs on the same chip. The IC was integrated on a dc–dc magnetic-less boost converter able to operate at a frequency of 1 MHz. The IC performance and footprint are compared to the same circuit realized with discrete Si and SiC vertical devices, showing the potential of GaN power ICs for efficient and compact power converters.

Journal ArticleDOI
TL;DR: The performance of the proposed converter, in terms of voltage stress, voltage gain, and efficiency, has been analyzed, and a comprehensive comparison between the presented topology and other similar topologies presented is presented.
Abstract: In this paper, an optimal structure for a high step-up, non-isolated dc-dc converter is proposed. In this topology, the required high voltage gain can be obtained with low number of elements. Furthermore, by implementing an auxiliary circuit, zero voltage switching (ZVS) condition for the switches is provided, input current ripple has been reduced to almost zero, and all of the power diodes turn off and on under zero current conditions. In the proposed structure, to regulate voltage gain, the extendable number of diode-capacitor voltage multiplier (DCVM) stages are combined with a coupled inductor. Voltage stresses across the semiconductors can be regulated by the number of the DCVM stages and the turns-ratio of the coupled inductor. Thus, it provides two degrees of freedom for the designer to use low rated semiconductors, which increases the converter efficiency. In this paper, the performance of the proposed converter, in terms of voltage stress, voltage gain, and efficiency, has been analyzed, and a comprehensive comparison between the presented topology and other similar topologies presented. Finally, to verify the performance of the proposed topology, a 500 W (40 V/400 V) laboratory prototype has been developed and tested. The experimental results confirm its superiority and suitability.

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TL;DR: In this paper, the ultrafast reverse recovery β -Ga2O3 Schottky barrier diode (SBD) with improved breakdown voltage is proposed and investigated experimentally, which features the compound termination, consisting of air space field plate and thermal oxidation terminal.
Abstract: 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 75 ns and ultralow reverse recovery charge of 10 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

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TL;DR: In this paper, a comprehensive review summarizes the current progress, understanding, and challenges in vertical GaN power devices, which can serve as not only a gateway for those interested in the field but also a critical reference for researchers in the wide bandgap semiconductor and power electronics community.
Abstract: Vertical gallium nitride (GaN) power devices are enabling next-generation power electronic devices and systems with higher energy efficiency, higher power density, faster switching, and smaller form factor. In Part I of this review, we have reviewed the basic design principles and physics of building blocks of vertical GaN power devices, i.e., Schottky barrier diodes and p-n diodes. Key topics such as materials engineering, device engineering, avalanche breakdown, and leakage mechanisms are discussed. In Part II of this review, several more advanced power rectifiers are discussed, including junction barrier Schottky (JBS) rectifiers, merged p-n/Schottky (MPS) rectifiers, and trench metal–insulator–semiconductor barrier Schottky (TMBS) rectifiers. Normally- OFF GaN power transistors have been realized in various advanced device structures, including current aperture vertical electron transistors (CAVETs), junction field-effect transistors (JFETs), metal–oxide–semiconductor field-effect transistors (MOSFETs), and fin field-effect transistors (FinFETs). A detailed analysis on their performance metrics is provided, with special emphasis on the impacts of key fabrication processes such as etching, ion implantation, and surface treatment. Lastly, exciting progress has been made on selective area doping and regrowth, a critical process for the fabrication of vertical GaN power devices. Various materials characterization techniques and surface treatments have proven to be beneficial in aiding this rapid development. This timely and comprehensive review summarizes the current progress, understanding, and challenges in vertical GaN power devices, which can serve as not only a gateway for those interested in the field but also a critical reference for researchers in the wide bandgap semiconductor and power electronics community.