Leakage Current Modelling and Optimization of β-Ga 2 O 3 Schottky Barrier Diode with Ni Contact under High Reverse Voltage

Abstract

The reverse leakage current under high reverse voltage of a Ni/β-Ga 2 O 3 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 β-Ga 2 O 3 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 mΩ·cm2, respectively, fairly close to measurement values of 440 V and 2.79 mΩ·cm2. Optimization is performed based on the insertion of an intrinsic layer between Ni and the β-Ga 2 O 3 drift layer. It was found that 0.4 μm gave better Baliga’s figure of merit of 9.48107 W·cm−2 with breakdown voltage and specific on-resistance of 465 V and 2.28 mΩ·cm2, 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 × 109 W·cm−2 and 1.98 mΩ·cm2 respectively.