Exponential absorption edge and implantation-induced modifications in amorphous gallium arsenide

Abstract Implantation-induced microstructural modifications have been measured in amorphous GaAs using Raman scattering spectroscopy and optical absorption in the subgap region. Additional evidence is given that the amorphous phase consists of two components which continuously evolve as a function of ion dose. A characteristic disorder-related Urbach parameter from the absorption measurements was used as a measure of the total disorder at each dose, whereas Raman results enabled the separation of a random component (amorphous continuous random network (a-CRN)) and a medium-rangeordered component (amorphous boson peak (a-Br)) of the amorphous network. As the dose is increased, the a-CRN fraction gradually converts into the a-BP fraction. The decrease in the remaining a-CRN fraction with increasing dose correlates with the decrease in the disorder as observed by absorption measurements and the Urbach parameter.