Evidence of thermionic emission in forward biased β-Ga2O3 Schottky diodes at Boltzmann doping limit

Abstract

A near-ideal and homogeneous β-Ga2O3 Schottky diode with Co contact for a doping level of ∼4.2 × 1017 cm−3 in the drift layer where the Boltzmann approximation is valid is reported. Unlike Si or GaN, thermionic emission is shown to be the dominant current conduction mechanism in the β-Ga2O3 Schottky diode at this doping level. A wide depletion region appended with a large built-in potential is observed to limit the thermionic field emission current, which is otherwise evident in narrower bandgap semiconductor (such as Si or GaN) Schottky diodes having a similar carrier concentration in the drift region. The results shown in this study can be used to identify the theoretical limits of drift layer doping beyond which the ideality factor and reverse leakage current should start deteriorating in ultra-wide bandgap semiconductor based Schottky diodes.