Trapping Effects in Si δ-Doped β-Ga2O3 MESFETs on an Fe-Doped β-Ga2O3 Substrate

Threshold voltage instability was observed on beta-Ga2O3 transistors using double-pulsed current-voltage and constant drain current deep level transient spectroscopy (DLTS) measurements. A total instability of 0.78 V was attributed to two distinct trap levels, at E-C-0.70 and E-C-0.77 eV, which need to be mitigated for future applications. The traps are likely located near the gate-drain edge and below the delta-doped layer, which is determined through the DLTS technique and an understanding of the fill and empty biasing conditions. The trap modulation was consistent with a gate leakage-based trap filling mechanism, which was demonstrated. It is likely that Fe is playing a role in the observed dispersion due to the close proximity of the Fe substrate.