The influence of secondary radiation defects on the redistribution of impurity ions due to high temperature proton irradiation

Experimental investigations of diffusion enhanced by high temperature proton irradiation (RED), using secondary ion mass-spectrometry (SIMS), showed that the redistribution of impurities in silicon displaced two or more extrema near Rsub(p), the projected range of protons. The maximum to minimum impurity concentration ratio was sometimes more than an order of magnitude. Simple theoretical treatments involving uphill diffusion and two-stream processes could explain only small values of extrema. To explain the observed max to min ratios one has to assume too large, unreal vacancy concentrations. During the diffusion process, impurities are electrically charged, not neutral, thus internal electrical fields arise due to impurities, radiation defects, electrons and holes. Such fields should be considered in detailed physical models of RED. The purpose of this work is to give a theoretical treatment of a physical model of RED with an internal electric field taken into account to support this explanation by different experiments. (author)