Effect of Rare-Earth Doping on the Microhardness of Silicon and Germanium

Abstract

The effect of rare-earth (Gd, Dy, Er, and Nd) doping on the mechanical properties of Si and Ge single crystals was studied. The results demonstrate that rare-earth dopants may both increase and decrease the microhardness of Si and Ge, depending on their concentration. This behavior results from the competition between two processes. On the one hand, rare-earth atoms and their accumulations hinder dislocation movement, thereby raising the microhardness of covalent semiconductors. On the other hand, the gettering of unintentional impurities by rare-earth dopants in the melt leads to a reduction in microhardness in the seed-end portion of the ingot.