A new sulfur passivation technique, the sulfur vapor glow discharge, has been developed to form a thick sulfide layer on GaAs surface. By using Auger electron spectroscopy and x‐ray photoelectron spectroscopy measurements, the main composition of the passivation layer is found to be gallium sulfide without the existence of unstable As–S bonds. The stability of the passivation effect is demonstrated by the nondecaying behavior of the photoluminescence intensity of the GaAs passivation surface under the illumination of the laser beam with very high intensity. ©1996 American Institute of Physics.