Reactive ion beam etching (RIBE) of GaAs, GaP, AlGaAs, and GaSb was performed in a Cl2–Ar mixture using an inductively coupled plasma source. The etch rates and yields were strongly affected by ion energy and substrate temperature. The RIBE was dominated by ion-assisted etching at ≪600 eV and by physical sputtering beyond 600 eV. The temperature dependence of the etch rates revealed three different regimes, depending on the substrate temperature: (1) sputtering-etch limited, (2) products-desorption limited, and (3) mass-transfer limited regions. GaSb showed the overall highest etch rates, while GaAs and AlGaAs were etched at the same rates. The etched features showed extremely smooth morphologies with anisotropic sidewalls. © 1999 American Vacuum Society.