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.

No abstract

No abstract

In this work, we demonstrate lateral β-Ga 2 O 3 Schottky barrier diode (SBD) with a high permittivity (highk) dielectric superjunction (SJ) structure. Trenches are patterned on the doped β-Ga 2 O 3 epilayer from anode to cathode and high permittivity BaTiO 3 dielectric is deposited on the trenches to uniformly distribute the electric field in the epilayer, which circumvents the extreme difficulties in achieving charge balance using conventional p-n superjunction structures in β-Ga 2 O 3 due to the lack of shallow acceptors. The proposed structure also enables the use of heavily doped epilayer to reduce on-resistance and also can achieve high breakdown voltage due to charge balance effect arising out of dielectric polarization. SBD on an epilayer with a sheet charge of 1.5×10 13 cm −2 demonstrates a specific on resistance (R on−sp ) of 1.65 mΩ-cm 2 and a breakdown voltage (V BR ) of 1487 V for an anode to cathode length of 5 µm rendering a Power figure of Merit (PFOM) of 1.34 GW/cm 2 when normalized to the entire device footprint. Normalizing to the active current conducting area yields a PFOM of 2.7 GW/cm 2 which crosses the SiC unipolar PFOM. These results using the proposed device structure demonstrates great promise for β-Ga 2 O 3 in multi-kilovolt class applications.

We report a vertical β-Ga2O3 Schottky barrier diode (SBD) with BaTiO3 as field plate oxide on a low doped thick epitaxial layer exhibiting 2.1 kV breakdown voltage. A thick drift layer of 11  μm with a low effective doping concentration of 8 × 1015 cm–3 is used to achieve high breakdown voltage. Using the high-k dielectric with a dielectric constant of 248, the breakdown voltage increases from 816 V for the non-field-plated SBD to 2152 V (>2× improvement) for the field-plated SBD without compromising the on-state performance. The diode dimensions are varied to analyze the effect of edge high-field related leakage with reverse bias and also the effect of current spreading during forward operation. Very uniform distribution of breakdown voltages of 2152 ± 20 V are observed for the diode diameters from 50 to 300  μm for the field-plated SBDs. The on and off state power losses are also analyzed and compared with the non-field-plated devices and the switching losses are estimated analytically.