Capacitance versus voltage curves and deep‐level transient spectroscopy have been used to investigate the effects of BCl3magnetron ion etching on the shallow donor concentration and deep‐level defects in GaAs. Capacitance versus voltage data reveal that the shallow donor concentration is unaffected by the etching process at power densities ranging from 0.08 to 0.4 W/cm2. Capacitance transient measurements reveal thermal emission of electrons from two deep defect sites with activation energies of 0.25 and 0.74 eV which were unaffected by the etching process. A broad, deep‐level transient spectroscopy peak, characterized by an activation energy for thermal emission of electrons of 0.37 eV, was also observed in the etched sample, but not in the unetched sample. Defect depth profiling of the 0.37 eV peak indicates the concentration of this defect to increase with increasing etch power.