Inductively Coupled Plasma Reactive Ion Etching with SiCl4 Gas for Recessed Gate AlGaN/GaN Heterostructure Field Effect Transistor

Abstract

An extremely low and controllable etching rate of 1.25 nm/min for GaN is obtained with SiCl4 in inductively coupled plasma reactive ion etching. By atomic force microscope, the etched surface is observed to be as smooth as the as-grown surface. The etching technology is applied to the fabrication of recessed gate AlGaN/GaN heterostructure field effect transistors (HFETs). The HFETs showed good drain current–drain voltage characteristics with the values estimated from the AlGaN layer thickness decrease. In the positive-gate bias, the gate leakage current increases sharply with an n-value of 1.68, improved from 4.09 without etching. The negative bias current remains similar to that of the un-etched sample. Carrier drift mobility also remained approximately the same value of 1500 cm2 V-1 s-1. Thus, no HFET performance degradation caused by the etching is observed.