Improvement in the channel mobility of a recess-gate GaN MOSFET with Al0.28Si0.72OX gate dielectric using the AlGaN/GaN selective-area regrowth method on a GaN-on-Si substrate

Abstract In this study, we fabricated a recess-gate GaN MOSFET with an Al 0.28 Si 0.72 O X dielectric using the AlGaN/GaN selective-area regrowth method. Normally-off operation is successfully achieved, i.e. the threshold voltage is > 0 V. Compared to the common recess-gate GaN MOSFET fabricated using the inductively-coupled plasma reactive ion etching method, it can be seen that there is an approximately 2 times enhancement of the channel mobility because of the reduced damage to the Al 0.28 Si 0.72 O X /GaN interface. Accordingly, an improved drain current and on-resistance are both observed. Moreover, the recess-gate GaN MOSFET with an Al 0.28 Si 0.72 O X dielectric fabricated using the selective-area growth method exhibits a rising channel mobility as the temperature increases due to the diminished trap occupation by thermal de-trapping. These results indicate the benefit of a GaN MOSFET with an AlSiO-based gate stack for the operation under high temperatures exceeding the normal operating range.