High Breakdown Voltage (−201) $\beta $ -Ga2O3 Schottky Rectifiers

Abstract

$\beta $ -Ga2O3 Schottky barrier diodes were fabricated in a vertical geometry structure consisting of Ni/Au rectifying contacts without edge termination on Si-doped epitaxial layers ( $10~\mu \text{m}$ , $\text{n}\sim 4\times 10^{15}$ cm $^{-3})$ on Sn-doped bulk Ga2O3 substrates with full-area Ti/Au back Ohmic contacts. The reverse breakdown voltage, ${V} _ \text {BR}$ , was a function of rectifying contact area, ranging from 1600 V at $3.1\times 10^{-6}$ cm2 (20- $\mu \text{m}$ diameter) to ~250 V at $2.2{\times }10^{-3}$ cm $^{-2}$ (0.53-mm diameter). The current density near breakdown was not strongly dependent on contact circumference but did scale with contact area, indicating that the bulk current contribution was dominant. The lowest ON-state resistance, ${R} _\text {on}$ , was 1.6 $\text{m}\Omega \cdot $ cm2 for the largest diode and 25 $\text{m}\Omega \cdot $ cm2 for the 1600-V rectifier, leading to a Baliga figure-of-merit ( ${V} _\text {BR}^{2}/{R} _\text {on})$ for the latter of approximately 102.4 MW $\cdot $ cm $^{-2}$ . The ON-OFF ratio was measured at a forward voltage of 1.3 V and ranged from $3\times 10^{7}$ to $2.5\times 10^{6}$ for reverse biases from −5 to −40 V and showed only a small dependence on temperature in the range from 25 °C to 100 °C.