Electrical Double-Layer Modeling of Different Al-Content on the Performance of AlGaN/GaN HEMTs

Abstract

The continuous tuning of the sheet electron density in GaN based transistors by Al content in the AlGaN layer is of great technological significance. A new physical model of the sheet electron density is proposed based on the electric double-layer theory. By comparing the sheet electron density and the threshold voltage predicted by the proposed model with those experimental data reported in the literature, a linear dependent relation can be found. Thus, the formation of electric double-layer at the AlGaN/GaN interface could be a physical origin of the sheet electron density. The proposed model predicates that the electric field distribution in the AlGaN layer is inhomogeneous, which agrees well with recently experimental results and still remains to be unraveled. These findings will benefit to better understand the physical mechanism of GaN based transistors and a possibility to improve its performance.