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In this work, we report on the growth of highmobility β-Ga2O3 homoepitaxial thin films grown at a temperature much lower than the conventional growth temperature window for metalorganic vapor phase epitaxy. Low-temperature β-Ga2O3 thin films grown at 600 • C on Fe-doped (010) bulk substrates exhibits remarkable crystalline quality which is evident from the measured room temperature Hall mobility of 186 cm 2 /Vs for the unintentionally doped films. N-type doping is achieved by using Si as a dopant and a controllable doping in the range of 2×10 16 -2×10 19 cm −3 is studied. Si incorporation and activation is studied by comparing silicon concentration from secondary ion mass spectroscopy (SIMS) and electron concentration from temperature-dependent Hall measurements. The films exhibit high purity (low C and H concentrations) with very low concentration of compensating acceptors (2×10 15 cm −3 ) even at this growth temperature. Additionally, abrupt doping profile with forward decay of ∼ 5nm/dec (10 times improvement compared to what is observed for thin films grown at 810 • C) is demonstrated by growing at a lower temperature.

β-Ga2O3 metal-semiconductor field-effect transistors are realized with superior reverse breakdown voltages (VBR) and ON currents (IDMAX). A sandwiched SiNx dielectric field-plate design is utilized that prevents etching-related damage in the active region and a deep mesa-etching was used to reduce reverse leakage. The device with LGD=34.5μm exhibits an IDMAX of 56 mA/mm, a high ION/IOFF ratio >108 and a very low reverse leakage until catastrophic breakdown at ∼4.4kV. A power figure of merit (PFOM) of 132 MW/cm2 was calculated for a VBR of ∼4.4kV. The reported results are the first >4kV-class Ga2O3 transistors to surpass the theoretical FOM of Silicon.

We report on n-type degenerate doping in β-(Al0.26Ga0.74)2O3 epitaxial thin films grown by metalorganic vapor-phase epitaxy and modulation doping in β-(Al0.26Ga0.74)2O3/β-Ga2O3 heterostructures. Alloy composition is confirmed using high-resolution X-ray diffraction measurements. Carrier concentration in the thin films is proportional to the silane molar flow. Room-temperature Hall measurements showed a high carrier concentration of 6 × 1018 cm–3 to 7.3 × 1019 cm−3 with a corresponding electron mobility between 53–27 cm2 V–1 s–1 in uniformly doped β-(Al0.26Ga0.74)2O3 layers. Modulation doping is used to realize a total electron sheet charge of 2.3 × 1012 cm−2 in a β-(Al0.26Ga0.74)2O3/β-Ga2O3 heterostructure using a uniformly doped β-(Al0.26Ga0.74)2O3 barrier layer and a thin spacer layer.

We report on the modeling of polarization-induced two-dimensional electron gas (2DEG) formation at ε-AlGaO 3 /ε-Ga 2 O 3 heterointerface and the effect of spontaneous polarization (P sp ) reversal on 2DEG density in ε-Ga 2 O 3 /ε-AlGaO 3 /ε-Ga 2 O 3 double heterostructures. Density-functional theory (DFT) is utilized to calculate the material properties of ε-Ga 2 O 3 and ε-AlGaO 3 alloys. Using Schrödinger-Poisson solver along with DFT calculated parameters, the 2DEG density is calculated as a function of barrier type and thickness. By optimizing the layer thicknesses of ε-Ga 2 O 3 /ε-AlGaO 3 /ε-Ga 2 O 3 heterostructures, charge contrast ratios exceeding 1600 are obtained. This computational study indicates the high potential for ε-Ga 2 O 3 -based heterostructure devices for non-volatile memories and neuromorphic applications.