Depth distributions of 300-keV protons implanted in n-type GaAs and characteristics of the associated damage in the crystalline material have been obtained. Range profiles of the implanted 1H ions as a function of substrate implantation temperature have been determined using secondary ion mass spectrometry for fluences of 5×1014 and 5×1015 cm−2. The projected range for the protons was approximately 2.7 μm for the room temperature implants, but a significant rearrangement of the 1H atoms occurred during elevated temperature implantation. While cross-sectional transmission electron microscopy showed no evidence of crystal damage in as-implanted wafers, plan-view measurements revealed platelike damage structures in the surface region (< 1μm).