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 (gm) and threshold voltage (Vth), while also suppressing gate leakage (IGS) and mitigating gate lag, collectively improving power performance (Pout, PAE, Gain). Additionally, ALE reduces parasitic capacitances, increasing cutoff frequencies (fT/fMAX) and lowering noise figure (NFmin). Thus, ALE is a highly promising technique for advancing next-generation high-frequency applications.