Vertical Geometry, 2-A Forward Current Ga2O3 Schottky Rectifiers on Bulk Ga2O3 Substrates

Abstract

Large area (up to 0.2 cm2) Ga2O3 rectifiers without edge termination were fabricated on a Si-doped n-Ga2O3 drift layer grown by halide vapor phase epitaxy on a Sn-doped n+Ga2O3 (001) substrate. A forward current of 2.2 A was achieved in single-sweep voltage mode, a record for Ga2O3 rectifiers. The on-state resistance was $0.26~\Omega ~ \cdot$ cm2 for these largest diodes, decreasing to $5.9\times 10^{-4} \Omega \,\, \cdot$ cm2 for $40\times 40\,\,\mu \text{m}^{2}$ devices. The temperature dependence (25 °C–125 °C) of forward current density was used to extract the barrier height of 1.08 eV for Ni and a Richardson’s constant of 48 A $\cdot$ cm−2 $\cdot \,\,\text{K}^{-2}$ . Ideality factors were in the range 1.01–1.05, with the barrier height decreasing with temperature. The reverse breakdown was a strong function of diode area, decreasing from 466 V ( $1.6\times 10^{-5}$ cm2 to 15 V for 0.2 cm2. This led to power figure-of-merits ( ${V}_{B}^{2}/\text{R}_{\mathrm{ON}})$ in the range $3.68\times 10^{8}$ –865 W $\cdot$ cm−2 over this area range. The reverse breakdown voltage scaled approximately as the contact perimeter, indicating it was dominated by the surface and decreased with temperature with a negative temperature coefficient of 0.45 V $\cdot \,\,\text{K}^{-1}$ . The reverse recovery time when switching from +1 V to reverse bias was 34 ns.