Change of optical properties during ion induced amorphization of AuIn2 films

The attenuated total reflection (ATR) technique has been combined with low temperature ion irradiation allowing to study the changes of optical properties of AuIn2 films under bombardment. For this purpose, crystalline films were irradiated at 80 K with 350 keV Ar+ ions resulting in a stepwise amorphization as indicated by accompanying in situ resistance measurements. It is demonstrated that this ion induced amorphization also leads to significant changes of the real and imaginary part of the index of refraction and its dispersion relation, which can be traced back to a disappearance of band structure effects in the amorphous phase. Based on the optical information, a procedure can be developed to extract the amorphous volume fraction, which, as a function of the ion fluence, compares very well with the corresponding results obtained from the resistance data. (C) 1997 Elsevier Science B.V.