EN
GaAs samples doped with indium atoms by ion implantation and thermal annealed were studied using a channelling method, Rutherford backscattering, and an ellipsometry. From these measurements it was observed that the layer implanted with 3×10^{16} cm^{-2} indium dose was totally damaged and its optical properties, namely a refraction index n and an extinction coefficient k, corresponded to the amorphous material. Subsequent isobaric heating of the implanted samples resulted in recovery of the crystalline structures with simultaneous change of the n and k index values.