Dry etching characteristics of single crystal (100) CdTe epitaxial layers grown on GaAs substrates were studied using CH 4 , H 2 , and Ar as process gases in an electron cyclotron resonance plasma. A smooth and anisotropic etching was obtained with CH 4 , H 2 , and Ar. No hydrocarbon polymer was found on the etched surface, which was confirmed by x-ray photoelectron spectroscopy measurement. Etching of the CdTe surface was also possible with H 2 and Ar; however, no etching was observed in the absence of H 2 . Dependence of the etch rate on plasma gas composition and flow rates was studied. Mechanisms of etching with and without CH 4 supply were also studied. Etched CdTe layers also showed no deterioration of electrical properties, which was confirmed by photoluminescence measurement at 4.2 K and Hall measurement at 300 K.