Comparison of Digital and Atomic Layer Etching for Gate Recess in AlGaN/GaN MOSHEMTs for Ka-Band

This study compares digital etching (DE) and atomic layer etching (ALE) for gate recessing in AlGaN/GaN metal oxide semiconductor high-electro-mobility transistors (MOSHEMTs) on Si substrate. While DE reduces plasma damage, it suffers from residual defects and etch variability. In contrast, ALE’s self-limiting mechanism enables a smoother surface, improving carrier transport and reducing charge traps. This enhances transconductance ( g m ) and threshold voltage ( V th ), while also suppressing gate leakage ( I GS ) and mitigating gate lag, collectively improving power performance ( P out , PAE, Gain). Additionally, ALE reduces parasitic capacitances, increasing cutoff frequencies ( f T / f MAX ) and lowering noise figure ( NF min ). Thus, ALE is a highly promising technique for advancing next-generation high-frequency applications.