The characteristics of GaAs etched using planar inductively coupled plasmas (ICP) of BCl3, BCl3/Ar and BCl3/Ne are reported. The etch rates generally increased with ICP source power and reactive ion etching (RIE) chuck power, while decreasing with increase of pressure. Anisotropic etched features were achieved through sidewall passivation, with a selectivity of GaAs etch rate to a photoresist of similar to3:1. BCl3/Ar plasmas provided a factor of two times higher etch rate than BCl3/Ne. Etched surface morphology was generally smooth (RMS roughness < 2 nm) RMS roughness was 37.5 nm). XPS showed that the etched GaAs surface was chemically clean and residue-free. (C) 2004 Elsevier B.V. All rights reserved.