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Power- and Spectral-Dependent Photon-Recycling Effects in a Double-Junction Gallium Arsenide Photodiode
摘要： Photon recycling effects improve radiative efficiencies of semiconductor materials, and play important roles in the design of high performance optoelectronic devices. Conventional research mostly studies the impact of photon recycling on the voltage of photodiodes. Here we systematically analyze the photon response of a microscale gallium arsenide (GaAs) based double junction photodiode. In such a device, the current matching condition between two subcells is determined by their photon coupling. Photodynamics in the device is examined and reveals the material’s internal quantum efficiencies. By leveraging photon distributions inside the device, we discover that its photocurrent and spectral responses are highly dependent on the illumination intensity. Consistent with theoretical analyses, the device’s photocurrents exhibit linear and superlinear power dependent characteristics under near-infrared and violet-blue illuminations, respectively. Due to strongly enhanced photon recycling effects under strong illumination, broadband photon responses (external quantum efficiency close to 50% from 400 nm to 800 nm) could be achieved in such a strongly current mismatched GaAs dual junction device. The understanding of photon processes in such devices would offer routes to the design of high-performance photodetectors and solar cells.
关键词： photovoltaics,photodetectors,gallium arsenide,photon recycling,multijunction
更新于2025-09-23 15:23:52
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[IEEE 2018 IEEE CPMT Symposium Japan (ICSJ) - Kyoto, Japan (2018.11.19-2018.11.21)] 2018 IEEE CPMT Symposium Japan (ICSJ) - Study on corundum-structured p-type iridium oxide thin films and band alignment at iridium oxide /gallium oxide hetero-junction
摘要： Corundum-structured iridium oxide, showing p-type conductivity, is a powerful candidate material for forming high-quality pn hetero-junctions with gallium oxide. We have succeeded in fabricating corundum-structured iridium oxide thin films on sapphire substrates. According to the optical transmittance measurement, the optical bandgap of iridium oxide was found to be approximately 3.0 eV. Furthermore, the band alignment at the iridium oxide /gallium oxide interface was investigated by X-ray photoemission spectroscopy, revealing a staggered-gap (type-Ⅱ) with the valence and conduction band offsets of 3.3 eV and 1.0 eV, respectively.
关键词： p-type oxide semiconductor,band alignment,gallium oxide
更新于2025-09-23 15:22:29
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Threshold switching and memory behaviors of epitaxially regrown GaN-on-GaN vertical p-n diodes with high temperature stability
摘要： This letter reports the observation of threshold switching and memory behaviors of epitaxially regrown GaN-on-GaN vertical p-n diodes. This mechanism was ascribed to the conductive path formed by traps in the insulating layer at the regrowth interface after soft breakdown. The device can reliably switch more than 1000 cycles at both room temperature and 300 oC with small fluctuation on the set and reset voltage. The set voltage increased with the increasing temperature due to the enhanced thermal detrapping effect that made it harder to form conductive path at high temperatures. Besides, the device showed memory behaviors when the reset voltage was higher than 4.4 V. This work can serve as important references to further developing GaN-based memory devices and integrated circuits.
关键词： memory,breakdown,wide bandgap semiconductor,threshold switching,p-n diodes,Gallium nitride
更新于2025-09-23 15:22:29
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Corona assisted gallium oxide nanowire growth on silicon carbide
摘要： This article reports on the use of corona discharge to assist the vapor liquid solid growth of gallium oxide nanowires on silicon carbide substrates. The corona discharge increases the nucleation efficiency of the gold catalysts from 60 % to 98 % for 3C-SiC(111)/Si(111) Si-face substrates and from 15 % to 80 % for 6H-SiC(0001) substrates. The growth mode and crystal structure are not affected by the corona discharge. The gallium oxide growth starts with the formation of [-311] oriented laterally overgrown terrace like nucleation zones with the gold catalyst particles floating on top. With evolving process time, the growth proceeds in the faster [010] direction, resulting in nanowires with an inclination angle of 51° towards the substrate surface. On silicon and sapphire substrates, the nucleation and growth of gallium oxide nanowires are suppressed.
关键词： B2. Silicon carbide,B1. Gallium oxide,A1. Nanowire,A1. Corona discharge,A3. Vapor liquid solid,A3. Vapor phase epitaxy
更新于2025-09-23 15:22:29
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Intricacies of the Determination of the Radiochemical Purity of 68Ga Preparations: Possibility of Sorption of Ionic 68Ga Species on Reversed-Phase Columns
摘要： The results of studying 68Ga radiopharmaceuticals using various TLC and HPLC procedures are compared. The data obtained reliably show that a part of 68Ga ionic species are irreversibly (under definite conditions) sorbed onto chromatographic columns packed with С18 reversed phase. The loss of 68Ga ionic species in the analysis can reach 90%. The 68Ga loss increases with an increase in pH of the preparation. At pH 2.5–3.0, the total loss of 68Ga ionic species on the chromatographic column does not exceed 15%. At pH 4.0, it is 65 ± 7% on the average, and at pH 6.0 it reaches 87 ± 8%. This effect should be taken into account in analysis of any 68Ga radiopharmaceuticals.
关键词： radiochemical purity,radiopharmaceuticals,sorption,complexation,HPLC,quality control,chromatography,gallium-68
更新于2025-09-23 15:22:29
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Improvement in Light Extraction Efficiency of InGaN/GaN Blue Light Emitting Diodes Using Sidewall Texturing
摘要： Herein, we reported the effects of the geometric morphology of the sidewall on the extraction ef?ciency of GaN-based light-emitting diodes (LEDs). We performed numerical analysis based on the ray-tracing method. We found that the extraction ef?ciency of the LEDs increased with the texturing of the sidewall. The light output intensity of the LEDs (at an injection current of 100 mA) increased by 13.8% after sidewall texturing. These results con?rmed that the geometric morphology of the sidewall plays an important role in improving the extraction ef?ciency of LEDs.
关键词： Texturing,Light Emitting Diodes,Gallium Nitride,Light Extraction Ef?ciency
更新于2025-09-23 15:22:29
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An Overview of the Ultrawide Bandgap Ga2O3 Semiconductor-Based Schottky Barrier Diode for Power Electronics Application
摘要： Gallium oxide (Ga2O3) is a new semiconductor material which has the advantage of ultrawide bandgap, high breakdown electric field, and large Baliga’s figure of merit (BFOM), so it is a promising candidate for the next-generation high-power devices including Schottky barrier diode (SBD). In this paper, the basic physical properties of Ga2O3 semiconductor have been analyzed. And the recent investigations on the Ga2O3-based SBD have been reviewed. Meanwhile, various methods for improving the performances including breakdown voltage and on-resistance have been summarized and compared. Finally, the prospect of Ga2O3-based SBD for power electronics application has been analyzed.
关键词： Breakdown electric field,Baliga’s figure of merit,On-resistance,Ultrawide bandgap semiconductor,Gallium oxide (Ga2O3),Power device,Schottky barrier diode (SBD)
更新于2025-09-23 15:22:29
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Improvement of electrical characteristics in regrown AlGaN/GaN MOSFETs by suppression of the residual interface charge
摘要： In this paper, the influence of a regrown interface on the electrical properties of AlGaN/GaN heterostructure was investigated for recessed-gate MOSFETs fabricated by selective area regrowth. The electron mobility of the two-dimensional electron gas (2DEG) on regrown AlGaN/GaN structures was degraded when the 2DEG was near the regrown interface. The regrown interface had high carrier concentrations and Si impurities that caused degradation of the electron mobility of the 2DEG. Unintentional carrier generation at the regrown interface was eliminated by ultraviolet (UV) treatment before regrowth. A regrown AlGaN/GaN MOSFET device was then fabricated using the UV treatment. The device exhibited good performance such as normally-off operation without hysteresis or leaks. Improvement of the electrical characteristics of AlGaN/GaN MOSFETs was thus achieved by suppression of regrown interface charge.
关键词： B2. Semiconducting gallium compounds,B3 High electron mobility transistors,A1. Interfaces,A3. Metalorganic vapor phase epitaxy,B1. Nitride
更新于2025-09-23 15:22:29
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GaN Integration Technology, an Ideal Candidate for High-Temperature Applications: A Review
摘要： In many leading industrial applications such as aerospace, military, automotive, and deep-well drilling, extreme temperature environment is the fundamental hindrance to the use of microelectronic devices. Developing an advanced technology with robust electrical and material properties dedicated for high-temperature environments represents a significant progress allowing to control and monitor the harsh environment regions. It may avoid using cooling structures while improving the reliability of the whole electronic systems. As a wide bandgap semiconductor, gallium nitride is considered as an ideal candidate for such environments, as well as in high-power and high-frequency applications. We review in this paper the main reasons that offer superiority to GaN devices over better-known technologies such as silicon (Si), silicon-on-insulator, gallium arsenide (GaAs), silicon germanium (SiGe), and silicon carbide (SiC). The theory of operation and main challenges at high temperature are discussed, notably those related to materials and contacts. In addition, the main limitations of GaN, including the technological (thermal and chemical) and intrinsic (current collapse and device self-heating) features are provided. In addition, the GaN devices recently developed for high-temperature applications are examined.
关键词： wide-bandgap semiconductors,high-temperature electronics,Extreme temperature applications,gallium-nitride technology
更新于2025-09-23 15:22:29
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AlGaN/GaN MIS-HEMT with PECVD SiNx, SiON, SiO2 as Gate Dielectric and Passivation Layer
摘要： Three different insulator layers SiNx, SiON, and SiO2 were used as a gate dielectric and passivation layer in AlGaN/GaN metal–insulator–semiconductor high-electron-mobility transistors (MIS-HEMT). The SiNx, SiON, and SiO2 were deposited by a plasma-enhanced chemical vapor deposition (PECVD) system. Great differences in the gate leakage current, breakdown voltage, interface traps, and current collapse were observed. The SiON MIS-HEMT exhibited the highest breakdown voltage and Ion/Ioff ratio. The SiNx MIS-HEMT performed well in current collapse but exhibited the highest gate leakage current density. The SiO2 MIS-HEMT possessed the lowest gate leakage current density but suffered from the early breakdown of the metal–insulator–semiconductor (MIS) diode. As for interface traps, the SiNx MIS-HEMT has the largest shallow trap density and the lowest deep trap density. The SiO2 MIS-HEMT has the largest deep trap density. The factors causing current collapse were confirmed by Photoluminescence (PL) spectra. Based on the direct current (DC) characteristics, SiNx and SiON both have advantages and disadvantages.
关键词： interface traps,MISHEMT,gallium nitride,PECVD,current collapse,dielectric layer
更新于2025-09-23 15:22:29