Leakage Current Modelling and Optimization of β-Ga2O3 Schottky Barrier Diode with Ni Contact under High Reverse Voltage

The reverse leakage current under high reverse voltage of a Ni/beta-Ga2O3 Schottky barrier diode (SBD) is numerically modelled and compared to measurements. universal Schottky tunnelling, thermionic emission and image-force lowering were taken into account. Furthermore, when type conversion under high reverse voltage has occurred at the top interface between Ni and beta-Ga2O3 and the SBD behaved as P-i-N diode, band to band tunnelling is proposed in association with the usually used Selberherr's Impact ionization to model avalanche breakdown. The obtained breakdown voltage and specific on-resistance value are 434 V and 2.13 m omega cm(2), respectively, fairly close to measurement values of 440 V and 2.79 m omega cm(2). Optimization is performed based on the insertion of an intrinsic layer between Ni and the beta-Ga2O3 drift layer. It was found that 0.4 mu m gave better Baliga's figure of merit of 9.4810(7) Wcm(-2) with breakdown voltage and specific on-resistance of 465 V and 2.28 m omega cm(2), respectively. Finally, a surface edge termination design based on TiO2 insulator plate is adopted and the best obtained breakdown voltage, Baliga's figure of merit and specific on-resistance were 1466 V, 1.98 x 10(9) Wcm(-2) and 1.98 m omega cm(2) respectively.