A5056402288- Ga2O3 and related materials
- ZnO doping and properties
- Advanced Photocatalysis Techniques
- Electronic and Structural Properties of Oxides
- Semiconductor materials and devices
- GaN-based semiconductor devices and materials
- Nanowire Synthesis and Applications
- Microwave Dielectric Ceramics Synthesis
- Chalcogenide Semiconductor Thin Films
- Semiconductor Quantum Structures and Devices
- Semiconductor materials and interfaces
- Multiferroics and related materials
- Luminescence Properties of Advanced Materials
- Quantum Dots Synthesis And Properties
- Magnesium Oxide Properties and Applications
- Advancements in Semiconductor Devices and Circuit Design
- Mechanical and Optical Resonators
University of Utah
2019-2024
University of California, Santa Barbara
2023
Arizona State University
2016-2022
Pennsylvania State University
2020
Kyma Technologies (United States)
2020
The Ohio State University
2020
University of Nebraska–Lincoln
2020
We report a vertical (001)β-Ga2O3 field-plated(FP) Schottky barrier diode (SBD) with novel extreme permittivity dielectric field oxide. A thin drift layer of 1.7μm was used to enable punch-through (PT) profile and very low differential specific on-resistance (Ron-sp)of 0.32 mΩ-cm2. The plate oxide facilitated the lateral spread electric beyond edge enabled breakdown voltage (Vbr) 687 V. termination efficiency increasesfrom 13.2%for non-field plated structure 61%for high structure. surface...
We demonstrate over 3 kV gate-pad-connected field plated (GPFP) $\beta$-Ga$_2$O$_3$ lateral MESFETs with high figure of merit (LFOM) using metalorganic vapor phase epitaxy (MOVPE) grown channel layers and regrown ohmic contact layers. Using an improved low-temperature MOVPE selective area process, we show that a total resistance to the as low 1.4 $\Omega$.mm can be achieved.The GPFP design adopted here PECVD (plasma-enhanced chemical deposition) deposited SiN$_x$ dielectric SiN$_x$/SiO$_2$...
Abstract β -Ga 2 O 3 metal–semiconductor field-effect transistors are realized with superior reverse breakdown voltages ( V BR ) and ON currents I DMAX ). A sandwiched SiN x dielectric field plate design is utilized that prevents etching-related damage in the active region a deep mesa-etching was used to reduce leakage. The device L GD = 34.5 μ m exhibits an of 56 mA mm −1 , high / OFF ratio >10 8 very low leakage until catastrophic at ∼4.4 kV. power figure merit (PFOM) 132 MW cm −2...
In this letter, fin-shape tri-gate <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$\beta $ </tex-math></inline-formula> -Ga2O3 lateral MESFETs are demonstrated with a high power figure of merit (PFOM) 0.95 GW/cm2 – record for any transistor to date. A low-temperature un-doped buffer-channel stack design is developed which demonstrates Hall and drift electron mobilities in doped channels allowing low ON...
We demonstrate a new substrate cleaning and buffer growth scheme in β-Ga2O3 epitaxial thin films using metal–organic vapor phase epitaxy (MOVPE). For the channel structure, low-temperature (LT, 600 °C) un-doped Ga2O3 was grown, followed by transition layer to high-temperature (HT, 810 Si-doped layers without interruption. The (010) Fe-doped uses solvent cleaning, additional hydrofluoric acid (49% water) treatment for 30 min before epilayer growth. This step is shown compensate parasitic Si...
We report on n-type degenerate doping in MOVPE grown \b{eta}-(Al0.26Ga0.74)2O3 epitaxial thin films and modulation \b{eta}-(Al0.26Ga0.74)2O3/\b{eta}-Ga2O3 heterostructure. Alloy composition is confirmed using HRXRD measurements. Carrier concentration the proportional to silane molar flow. Room temperature hall measurements showed a high carrier of 6x1018-7.3x1019 cm-3 with corresponding electron mobility 53-27 cm2/V.s uniformly-doped layers. Modulation used realize total sheet charge...
We report on the growth and characterization of metalorganic vapor-phase epitaxy-grown \b{eta}-(AlxGa1-x)2O3/\b{eta}-Ga2O3 modulation-doped heterostructures. Electron channel is realized in heterostructure by utilizing a delta-doped \b{eta}-(AlxGa1-x)2O3 barrier. characteristics are studied using transfer length method, capacitance-voltage Hall measurements. sheet charge density 1.06 x 1013 cm-2 mobility 111 cm2/Vs measured at room temperature. Fabricated transistor showed peak current 22...
We report on the modeling of polarization-induced two-dimensional electron gas (2DEG) formation at ε-AlGaO3/ε-Ga2O3 heterointerface and effect spontaneous polarization (Psp) reversal 2DEG density in ε-Ga2O3/ε-AlGaO3/ε-Ga2O3 double heterostructures. Density-functional theory (DFT) is utilized to calculate material properties ε-Ga2O3 ε-AlGaO3 alloys. Using Schrödinger–Poisson solver along with DFT calculated parameters, as a function barrier type thickness. By optimizing layer thicknesses...
We report on the first demonstration of metalorganic vapor phase epitaxy-regrown (MOVPE) ohmic contacts in an all MOVPE-grown β-Ga2O3 metal semiconductor field effect transistor (MESFET). The low-temperature (600 °C) heavy (n+) Si-doped regrown layers exhibit extremely high conductivity with a sheet resistance 73 Ω/□ and record low metal/n+-Ga2O3 contact 80 mΩ·mm specific resistivity 8.3 × 10−7 Ω·cm2 were achieved. fabricated MESFETs maximum ON current 130 mA mm−1 ION/IOFF ratio >1010....
Abstract In this work, a systematic photoluminescence (PL) study on three series of gallium oxide/aluminum oxide films and bulk single crystals is performed including comparing doping, epitaxial substrates, aluminum concentration. It observed that blue/green emission intensity strongly correlates with extended structural defects rather than the point frequently assumed. Bulk or Si-doped homoepitaxially grown (010) β-Ga 2 O 3 yield an intense dominant UV emission, while samples defects, such...
We report on silicon delta doping of metalorganic vapor-phase epitaxy-grown \b{eta}-Ga2O3 thin films using silane precursor. Delta-doped epitaxial are characterized capacitance-voltage profiling and secondary-ion mass spectroscopy. Electron sheet charge density in the range 2.9e12 cm-2 to 8e12 with a half width at maximum ranging from 6.2 nm 3.5 is measured. also demonstrate high (6.4e12 cm-2) degenerate two-dimensional electron gas delta-doped \b{eta}-(Al0.26Ga0.74)2O3/\b{eta}-Ga2O3...
Ultra-wide bandgap β-gallium oxide (Ga2O3) devices are of considerable interest with potential applications in both power electronics and radio frequency devices. However, current Ga2O3 device technologies limited by the material's low intrinsic electron mobility thermal conductivity. The former problem can be addressed employing modulation-doped β-(AlxGa1−x)2O3/Ga2O3 heterostructures architecture. In this work, (AlxGa1−x)2O3/Ga2O3 field effect transistors (MODFETs) have been investigated...
This paper reports on the modulation of Schottky barrier heights (SBH) three different orientations $\beta$-Ga$_2$O$_3$ by insertion an ultra-thin SiO$_2$ dielectric interlayer at metal-semiconductor junction, which can potentially lower Fermi-level pinning (FLP) effect due to metal-induced gap states (MIGS). Pt and Ni (MS) metal-interlayer-semiconductor (MIS) diodes were fabricated bulk n-type doped single crystal substrates along (010), (-201) (100) characterized room temperature...
The quasi-static anisotropic permittivity parameters of electrically insulating beta gallium oxide (β-Ga2O3) were determined by terahertz spectroscopy. Polarization-resolved frequency domain spectroscopy in the spectral range from 200 GHz to 1 THz was carried out on bulk crystals along different orientations. Principal directions for crystallographic axes c and b reciprocal lattice direction a*. No significant dispersion real part dielectric observed measured range. Our results are excellent...
Heteroepitaxy of β-phase gallium oxide (β-Ga2O3) thin films on foreign substrates shows promise for the development next-generation deep ultraviolet solar blind photodetectors and power electronic devices. In this work, influences film thickness crystallinity thermal conductivity (2̅01)-oriented β-Ga2O3 heteroepitaxial were investigated. Unintentionally doped grown c-plane sapphire with off-axis angles 0° 6° toward ⟨112̅0⟩ via metal–organic vapor phase epitaxy (MOVPE) low-pressure chemical...
High-quality dielectric-semiconductor interfaces are critical for reliable high-performance transistors. We report the in-situ metalorganic chemical vapor deposition (MOCVD) of Al$_2$O$_3$ on $\beta$-Ga$_2$O$_3$ as a potentially better alternative to most commonly used atomic layer (ALD). The growth is performed in same reactor Ga$_2$O$_3$ using trimethylaluminum and O$_2$ precursors without breaking vacuum at temperature 600 $^0$C. fast slow near interface traps Al$_2$O$_3$/ identified...
Monoclinic β-Ga2O3, an ultra-wide bandgap semiconductor, has seen enormous activity in recent years. However, the fundamental study of plasmon–phonon coupling that dictates electron transport properties not been possible due to difficulty achieving higher carrier density (without introducing chemical disorder). Here, we report a highly reversible, electrostatic doping β-Ga2O3 films with tunable densities using ion-gel-gated electric double-layer transistor configuration. Combining...
In this work, we report on the growth of high-mobility β-Ga2O3 homoepitaxial thin films grown at a temperature much lower than conventional window for metalorganic vapor phase epitaxy. Low-temperature 600 °C Fe-doped (010) bulk substrates exhibit remarkable crystalline quality, which is evident from measured room Hall mobility 186 cm2/V s unintentionally doped films. N-type doping achieved by using Si as dopant, and controllable in range 2 × 1016–2 1019 cm−3 studied. incorporation activation...
Homoepitaxial growth of β-Ga2O3 using metalorganic vapor-phase epitaxy (MOVPE) on several different crystal orientations has previously been studied, but the (2¯01) plane remained comparatively unexplored. To investigate this, we grew Si-doped and unintentionally doped (UID) homoepitaxial layers simultaneously Sn-doped (010) substrates under conditions optimized for growth. We report herein results from current–voltage capacitance–voltage (IV CV) deep level transient spectroscopy (DLTS)...
Abstract In this work, we use photoluminescence spectroscopy (PL) to monitor changes in the UV, blue, and green emission bands from n-type (010) Ga 2 O 3 films grown by metalorganic vapor phase epitaxy induced annealing at different temperatures under ambient. Annealing successively higher decreases overall PL yield UV intensity nearly same rates, indicating increase formation of least one non-radiative defect type. Simultaneously, ratios blue/UV green/UV increase, suggesting that defects...
We report a new type of structural defect in β-Ga2O3 homoepitaxial thin films grown by metalorganic vapor phase epitaxy, which we have dubbed as “sympetalous defects.” These consist line (for example, nanotube defect) the underlying substrate combined with multi-faceted inverted polycrystalline pyramid epitaxial film, may also be decorated twinned grains. In plan-view atomic force, scanning electron, or optical microscopies, sympetalous defects appear similar shape to polygonal etch pits...
By combining temperature-dependent resistivity and Hall effect measurements, we investigate donor state energy in Si-doped β-Ga2O3 films grown using metal-organic vapor phase epitaxy. High-magnetic field (H) measurements (–90 kOe ≤ H +90 kOe) showed non-linear resistance for T &lt; 150 K, revealing two-band conduction. Further analyses revealed carrier freeze out characteristics both bands yielding energies of ∼33.7 ∼45.6 meV. The former is consistent with the Si β-Ga2O3, whereas latter...
Herein we utilize polarized photoluminescence (PL) microscopy and spectral analysis to locate characterize many different types of µm-scale extended defects present in melt-grown bulk crystals metal-organic vapor-phase epitaxy (MOVPE)-grown epitaxial thin films β-Ga 2 O 3 β-(Al,Ga) . These include pits, divots, mounds, scratches, rotation domain boundaries, stacking faults, cracks, other defect categories. Some simply decrease overall PL yield, while others emit spectra than single crystal...