Modeling of Transformations and Concentration Waves in Ion-Bombarded Gallium Arsenide

A model which describes the altered layer formation with account for an autocatalytic phase transformation in gallium arsenide under high-fluence ion bombardment is developed. Model calculations were carried out revealing that the anomalous expansion of the subsurface layer with damaged structure found experimentally in GaAs can be attributed to an autocatatytic phase transformation which propagates like a Kholmogorov-Petrovskii-Piscunov wave. Possible mechanisms which can result in formation of concentration waves observed experimentally were treated and it was shown that these are most likely to occur due to post-bombardment relaxation processes.