Impact of drain-source leakage on the dynamic Ron of power HEMTs with p-GaN gate

Abstract

We present an extensive analysis of the impact of drain-source off-state leakage current on the dynamic on-resistance of GaN HEMTs with p-GaN gate. We analyzed two wafers with epitaxial layers grown under different conditions. The difference in the epitaxial layers gives an impact on the off-state leakage. We analyzed all the leakage components demonstrating that the wafer with lower off-state leakage shows a large dynamic R_on instability. Based on current transient measurements performed in temperature, this difference is explained by considering that a larger leakage (still below the nA) through the unintentionally-doped channel layer can ease the generation of positive charge at the bottom of the buffer, with consequent compensation of the dynamic R_on effect. The methodology presented in this paper constitutes a rapid and effective approach to evaluate the conductivity of the GaN channel layer, and its contribution to device stability.