摘要
Selective reactive ion etching of GaAs on AlGaAs in SiCl4/SiF4 plasma is reported. A selectivity ratio of 350:1 has been obtained at low power. A small decrease in the saturation current of gateless MODFET structures has been observed after etching the GaAs cap layer and has been ascribed to be due to low‐power ion damage of the AlGaAs layer. This process was applied to the fabrication of 0.2 μm T‐gate pseudomorphic MODFET’s. The dc and microwave performance of reactive‐ion‐etched devices and wet‐etched devices were identical. However, for these short‐gate‐length devices a threshold voltage standard deviation of 30 mV was obtained for the reactive‐ion‐etched devices as compared to 230 mV for the wet‐etched devices.