AN ASYMPTOTIC ANALYSIS OF THE KICK-OUT DIFFUSION MECHANISM

The kick-out model for impurity diffusion in semiconductors is studied . The kick-out mechanism is thought to play an important role in a num ber of applications, including the diffusion of zinc and chromium in g allium arsenide. Asymptotic solutions are derived for both one- and tw o-dimensional surface source problems. In the one-dimensional case, a mechanism for the destruction of self-interstitials is also incorporat ed. The calculated diffusion profiles have shapes which are typical of diffusion systems in which the kick-out mechanism is believed to be a ctive. For the two-dimensional problem, contours of constant impurity concentration are calculated and some are found to have the 'bird's be ak' shape which is frequently observed in experiments.