Chemically assisted ion beam etching using an Ar ion beam and Cl-2 and HCl Eases was investigated for the etching of high quality facets in InP. The etch rate, anisotropy, and surface morphology for the Cl-2 and HCL processes are compared for different conditions of substrate temperature and reactive gas flow rate. Elevated substrate temperatures above 150 degrees C were required due to the low volatility of InClx reaction products below this temperature. At higher substrate temperatures, etch rates in the range of 1-5 mu m/min using Cl-2 and 200-500 nm/min using HCl were obtained. Vertical etch profiles were obtained above 200 degrees C for Cl-2 and above 300 degrees C using HCl. The HCl process provided very smooth etched surfaces under most conditions investigated. Surface analysis using Auger electron spectroscopy and secondary ion mass spectroscopy techniques was conducted. Auger electron spectroscopy indicated surface depletion of in using Cl-2, HCl resulted in increased depletion of P. Secondary ion mass spectroscopy depth profiles carried out using deuterium gas indicated diffusion of deuterium greater than 10 mu m at a process temperature of 325 degrees C, while a postetch anneal at 325 degrees C/10 min was demonstrated to reduce the level of deuterium near the surface.