EFFECT OF ION-BEAM-INDUCED DISORDER ON OPTICAL INTERBAND-TRANSITIONS IN SI AND GAAS

Optical reflection spectra and their derivatives of Ar+ ion (75 keV) b ombarded single crystals of Si and GaAs, with fluence ranging from 5x1 0(11)-1x10(15) ions cm(-2), have been investigated in the spectral reg ion of interband optical transitions. The effect of ion-beam induced d isorder on the interband transitions in the two categories of semicond uctors (direct/indirect band gap) have been found to be quite differen t. This dissimilarity may be due to the different optical response of the intermediate microcrystalline component formed by ion-bombardment during the course of crystalline-to-amorphous transformation.