Reactive ion etching of InP with CH4/H2mixtures leads to hydrogen passivation of near‐surface Zn acceptors but not S donors. Secondary‐ion mass spectrometry (SIMS) measurements of CH4/D2etched samples show deuterium diffuses to a depth of 2000 A˚ inp‐InP (1.5×1018cm−3) when etching at a rate of 520 A˚/min and a temperature of about 80 °C. Acceptor passivation occurs to the same depth. Forn‐InP, no donor passivation is observed, even though SIMS shows deuterium diffusion to a depth of 7000 A˚. Annealing at 350 °C for 1 min restores carrier concentrations to near pre‐etched levels.