High rate (≤10 μm min−1) etching of GaAs, AlxGa1−xAs, and GaSb in Cl2/Ar or SiCl4/Ar discharges is reported. The etching was investigated as a function of discharge pressure, power density and composition, and changes in the etching rate of AlxGa1−xAs when SF6was added to the gas mixtures. Highly anisotropic etching was achieved with SiCl4for all materials, whereas a greater degree of chemical etching was evident with Cl2. Provided self‐biases were ≤50 V, excellent Schottky diode characteristics were exhibited by TiPtAu contacts on SiCl4or Cl2etched GaAs surfaces. Energetic‐ion bombardment caused carrier compensation up to 2200 Å from the surface inn‐type (1017cm−3) GaAs, with this depth being less for lower self‐biases. Photoluminescence decreases of 2–25 times were observed after reactive ion etching of GaAs for both types of discharge. Chlorine residues were typically present to a depth of<20 Å after etching, with cleaner surfaces obtained with SiCl4than with Cl2.