Comparison of side-gate modulation responses for AlGaN/GaN HEMTs on GaN substrates with and without C-doped GaN buffer layer

摘要

GaN HEMTs have promising potential as power transistors because of the excellent properties of GaN such as high carrier concentration, and high breakdown electric field. For optimum HEMT performance of GaN HEMT on GaN substrate, high-quality GaN substrates and buffers with high resistivities are important. However, unintentional residual impurities incorporated during growth results undoped GaN layer with low resistivity. In order to increase the resistivity, these impurities are compensated by doping the GaN with deep acceptors like carbon (C). In our previous works, we have reported that HEMT on C-doped GaN buffer showed a large modulation by side-gate (SG) measurement, and showed a hysteresis feature2) when bi-directional dual sweep SG measurement is done. In this report, we extend the study for SG measurements on two GaN HEMT devices with C-doped GaN buffer and no-buffer device.