Ion implanted impurity activation in a multi-element compound semiconductor crystal such as gallium arsenide, GaAs, over a broad integrated circuit device area, is accomplished using a short time anneal, in the proximity of a uniform concentration of the most volatile element of said crystal, in solid form, over the broad integrated circuit device area surface. A GaAs integrated circuit wafer having ion implanted impurities in the surface for an integrated circuit is annealed in the vicinity of 800.degree.-900.degree. C. for a time of the order of 1-20 seconds in the proximity of a uniform layer of solid arsenic.