III–V nitride semiconductors have great potential for optoelectronic and electronic devices due to their wide direct band gaps. Because GaN is chemically very stable, dry etching techniques must be established in order to fabricate devices. In this work, we report the reactive ion etching (RIE) of GaN using CHF3/Ar and C2ClF5/Ar plasmas. GaN films on (001) GaAs were grown by electron cyclotron resonance (ECR) plasma associated molecular beam epitaxy (MBE) and the films showed (0001)hexorientation along the surface normal. We used a Drytek DRIE‐184 rf plasma discharge RIE system with no ECR discharge or high energy Ar ion beam. The effects of rf plasma power, pressure, and gas flow rates on the etch rate were investigated and the surface contamination due to RIE was examined by XPS. The etch rate varied between 60 and 470 A˚/min. The conditions for etching were 100–500 W of rf plasma power, 60–300 mTorr of pressure, a CHF3or C2ClF5flow rate of 5–50 sccm and an Ar flow rate of 0–50 sccm. The highest etch rates were obtained with high rf plasma power and low pressure. ©1995 American Institute of Physics.