ON-Resistance of Ga₂O₃ Trench-MOS Schottky Barrier Diodes: Role of Sidewall Interface Trapping

We present a comprehensive study of the ON-resistance ( ${R} _{ \mathrm{\scriptscriptstyle ON}}$ ) of Ga2O3 trench-MOS Schottky barrier diodes (SBDs), with a focus on the effect of sidewall interface trapping. Capacitance–voltage characteristics of MOS-capacitors and current–voltage characteristics of trench SBDs were all repeatedly measured under increasing forward-bias stress voltage to at least +15 V. Both reveal an increase in negative charges trapped near the MOS interface under increasing forward bias, as well as slow detrapping. The slow detrapping in trench SBDs causes a current collapse and a delayed turn-on behavior in the trench SBDs due to sidewall depletion. Through modeling of the fresh ${R} _{ \mathrm{\scriptscriptstyle ON}}$ , we found that the sidewall depletion can be eliminated under sufficiently high forward bias. Interestingly, the dynamic ${R} _{ \mathrm{\scriptscriptstyle ON}}$ under the forward-bias stress is lower than the fresh ${R} _{ \mathrm{\scriptscriptstyle ON}}$ . Such an anomalous behavior is well-explained by analytical calculation of the apparent differential ${R} _{ \mathrm{\scriptscriptstyle ON}}$ , which can be lowered by a modulation of fin-channel conductivity under forward bias. This study highlights the importance of sidewall interface quality in trench-MOS SBDs and calls for scrutiny on the interpretation of the apparent differential ${R} _{ \mathrm{\scriptscriptstyle ON}}$ , as artificially low values may arise due to the voltage dependence of ${R} _{ \mathrm{\scriptscriptstyle ON}}$ .