Conditions have been developed for the deposition of stoichiometric thin films of amorphous gallium arsenide by the technique of flash evaporation. Structural properties of as‐deposited and annealed thin films ofa‐GaAs have been studied using x‐ray diffraction and transmission electron microscopy techniques. The as‐deposited films are noncrystalline, structural ordering starts at about 200 °C, and the film becomes crystalline at about 400 °C with the structure matching with that of polycrystalline GaAs. The as‐depositeda‐GaAs thin films have been passivated using hydrogen plasma under different conditions. The influence of hydrogenation on thesea‐GaAs films has been studied using Fourier transform infrared absorption spectroscopy. These data are explained in terms of the various types of hydrogen bondings and the results are in excellent agreement with the earlier investigations ona‐GaAs:H.