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

Wenshen Li,Kazuki Nomoto,Huili Grace Xing,Debdeep Jena,Zongyang Hu

doi:10.1109/ted.2021.3067856

Abstract

We present a comprehensive study of the ON-resistance ( R ON ) of Ga 2 O 3 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 ON , we found that the sidewall depletion can be eliminated under sufficiently high forward bias. Interestingly, the dynamic R ON under the forward-bias stress is lower than the fresh R ON . Such an anomalous behavior is well-explained by analytical calculation of the apparent differential R 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 ON , as artificially low values may arise due to the voltage dependence of R ON .

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