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

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 Ron 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 Ron 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.