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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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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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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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A review of the most recent progresses of state-of-art gallium oxide power devices
摘要： Until very recently, gallium oxide (Ga2O3) has aroused more and more interests in the area of power electronics due to its ultra-wide bandgap of 4.5–4.8 eV, estimated critical field of 8 MV/cm and decent intrinsic electron mobility limit of 250 cm2/(V·s), yielding a high Baliga’s figures-of-merit (FOM) of more than 3000, which is several times higher than GaN and SiC. In addition to its excellent material properties, potential low-cost and large size substrate through melt-grown methodology also endows β-Ga2O3 more potential for future low-cost power devices. This article focuses on reviewing the most recent advances of β-Ga2O3 based power devices. It will be starting with a brief introduction to the material properties of β-Ga2O3 and then the growth techniques of its native substrate, followed by the thin film epitaxial growth. The performance of state-of-art β-Ga2O3 devices, including diodes and FETs are fully discussed and compared. Finally, potential solutions to the challenges of β-Ga2O3 are also discussed and explored.
关键词： power electronics,power devices,gallium oxide
更新于2025-09-23 15:22:29
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Heteroepitaxial growth of thick <i>α</i> -Ga <sub/>2</sub> O <sub/>3</sub> film on sapphire (0001) by MIST-CVD technique
摘要： The 8 μm thick single-crystalline α-Ga2O3 epilayers have been heteroepitaxially grown on sapphire (0001) substrates via mist chemical vapor deposition technique. High resolution X-ray diffraction measurements show that the full-widths-at-half-maximum (FWHM) of rocking curves for the (0006) and (10-14) planes are 0.024° and 0.24°, and the corresponding densities of screw and edge dislocations are 2.24 × 106 and 1.63 × 109 cm?2, respectively, indicative of high single crystallinity. The out-of-plane and in-plane epitaxial relationships are [0001] α-Ga2O3//[0001] α-Al2O3 and [11-20] α-Ga2O3//[11-20] α-Al2O3, respectively. The lateral domain size is in micron scale and the indirect bandgap is determined as 5.03 eV by transmittance spectra. Raman measurement indicates that the lattice-mismatch induced compressive residual strain cannot be ruled out despite the large thickness of the α-Ga2O3 epilayer. The achieved high quality α-Ga2O3 may provide an alternative material platform for developing high performance power devices and solar-blind photodetectors.
关键词： chemical vapor deposition,ultra-wide bandgap semiconductor,gallium oxide,epitaxy
更新于2025-09-23 15:22:29
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Current transport mechanism of Mg/Au ohmic contacts to lightly doped n-type <i>β</i> -Ga <sub/>2</sub> O <sub/>3</sub>
摘要： The carrier transport mechanism of Mg/Au ohmic contact for lightly doped β-Ga2O3 is investigated. An excellent ohmic contact has been achieved when the sample was annealed at 400 °C and the specific contact resistance is 4.3 × 10?4 Ω·cm2. For the annealed sample, the temperature dependence of specific contact resistance is studied in the range from 300 to 375 K. The specific contact resistance is decreased from 4.3 × 10?4 to 1.59 × 10?4 Ω·cm2 with an increase of test temperature. As combination with the judge of E00, the basic mechanism of current transport is dominant by thermionic emission theory. The effective barrier height between Mg/Au and β-Ga2O3 is evaluated to be 0.1 eV for annealed sample by fitting experimental data with thermionic emission model.
关键词： effective barrier height,beta-gallium oxide,Mg/Au,ohmic contact,thermionic emission theory
更新于2025-09-23 15:22:29
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Gas sensing performance of GaOOH and β-Ga<sub>2</sub>O<sub>3</sub> synthesized by Hydrothermal method: A comparison
摘要： Gallium Oxy Hydrate (GaOOH) and β-Ga2O3 nanostructures in submicron scale have been synthesized at low temperature by surfactant-free hydro-thermal method. First, GaOOH has been synthesized using Gallium nitrate anhydrate, Ammonium hydroxide as precursors and double distilled water as solvent. As obtained GaOOH powders have been characterized by XRD, FE–SEM, UV–VIS, Thermo Gravimetric Analysis, I-V characteristics and BET surface analysis in order to reveal their structural, morphological, optical, thermal, electrical and surface properties. FE-SEM micrographs confirm the rod like and needle like morphologies of GaOOH and β- Ga2O3 samples, respectively. Porous nature of the samples observed through BET and BJH analyses. Synthesized GaOOH and β-Ga2O3 powders have been subjected to room temperature CO2 gas sensing in the range, 2000 ppm – 10000 ppm. GaOOH showed quick response of 80 s and fast recovery of 129 s at 8000 ppm while β-Ga2O3 showed quick response of 52 s at 8000 ppm and faster recovery of 98 s at 4000 ppm. Also, the repeatability studies were done for GaOOH and β-Ga2O3 films by exposing to different CO2 concentrations for a period of 6 consecutive days. β-Ga2O3 showed enhanced CO2 sensing response than that of GaOOH due to its better structural, electrical, morphological and surface properties.
关键词： Gallium Oxide (Ga2O3),Gallium Oxide Hydroxide (GaOOH),Hydrothermal method,Characterization,Room temperature CO2 sensing
更新于2025-09-23 15:21:21
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Extremely Low Dark Current and Detection Range Extension of Ga2O3 UV Photodetector using Sn Alloyed Nanostructures
摘要： A unique metal-semiconductor-metal (MSM) photodetector has been fabricated using Sn incorporation in Ga2O3 forming SnxGa1-xO nanostructures (Ns) with platinum (Pt) metal as contacts. The mixed nanostructures (MNs) has been attributed to an increment in the detection range of UV (254 – 302 nm) with ultra-low dark current, hence a potential device in the field of long range deep-UV detector. SnxGa1-xO (Ns) are deposited on c-plane sapphire using low-pressure chemical vapour deposition (LPCVD). From the X-ray diffraction results, existence both SnxGa1-xO and tetragonal SnO2 MNs are confirmed. The XRD peak shifts in SnxGa1-xO is attributed to the integration of Sn with Ga forming SnxGa1-xO alloy with x to be ~7.3% determined from the Vegard’s law. The FESEM images show the thick diameter wire-shaped nanostructures. The absorption spectra show a trace of two absorption edges corresponding to both SnxGa1-xO and SnO2 Ns. Photo to dark current ratio (PDCR) of the fabricated photodetector is large (103) at 2 V bias with fast fall time of 0.18 s. The detector reveals self-powered behaviour also with PDCR > 104 at 0 V bias. The dark current is ultra-low (13 pA at 5 V) due to high barrier height of Pt and the UV detection range has been extended from 254 – 302 nm with a very small drop in PDCR owing to incorporation of Sn.
关键词： LPCVD,Nanostructures,Photodetector,Gallium Oxide
更新于2025-09-23 15:21:01
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Optimized Growth of Gallium Oxide Thin Films Using Different Synthesis Processes
摘要： This paper investigates the optimized sputtering conditions for high quality gallium oxide (Ga2O3) thin films while maintaining a strong uniformity within a specific surface area. The research also analyzes the crystal structure and the morphology of gallium oxide (Ga2O3) thin films. We report a comprehensive investigation of two different types of Ga2O3 synthetization processes: (1) direct deposition using radio frequency (RF) magnetron sputter technique and (2) thermal oxidation of gallium nitride (GaN) samples. A detailed comparison is presented in terms of material characterization, surface analysis and electrical performance for each of the synthetization processes. X-ray photoelectron spectroscopy, scanning electron microscopy, atomic force microscopy and x-ray diffraction (XRD) are employed to study the gallium oxide (Ga2O3) epi-layers on each of the samples. Based on the analysis, Ga2O3 compound is found on all samples with a binding energy ranging from 21 eV to 21.38 eV. Depending on the synthetization process, the thickness varied from 20 nm to 100 nm for RF sputtering process and a maximum of 400 nm for thermal oxidation method. Additionally, the observations revealed that Ga2O3 is formed on the surface, as well as inside the gallium nitride (GaN) film after thermal oxidation. Crystal features are observed on the surface of each of the samples after annealing treatment while XRD analysis showed the presence of the beta (b) polymorph for the annealed samples. After thorough characterization, radio frequency sputtering technique proved to be superior due to its higher purity level and ability to create polycrystalline structures by adding temperature during deposition.
关键词： UHV RF magnetron sputtering,Gallium oxide,thermal oxidation,characterization
更新于2025-09-23 15:21:01
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Influence of precursor concentration and growth time on the surface morphology and crystallinity of α-Ga<sub>2</sub>O<sub>3</sub> thin films fabricated by mist chemical vapor deposition
摘要： Single-crystal thin films of gallium oxide (Ga2O3), an ultra-wide bandgap semiconductor, were fabricated on c-plane sapphire by mist chemical vapor deposition (mist CVD). The grown ?-Ga2O3 thin films had low surface roughness, and we characterized their initial crystal growth phase by using atomic force microscopy and X-ray diffraction. By varying the precursor concentration, we changed the surface roughness and crystallinity of the thin films. The lattice constants of the ?-Ga2O3 thin films almost matched those of the single crystal in the initial growth phase. We also found that these thin films grew hetero-epitaxially. Finally, mist CVD might have a very short incubation time in this system.
关键词： Gallium oxide,Surface morphology,Crystallinity,Precursor concentration,Mist chemical vapor deposition,Epitaxial growth,Wide bandgap semiconductors
更新于2025-09-23 15:21:01