Control of Dislocations and Sn Precipitations for Fabrication of Tensile-strained Ge on Ge_1-xSn_x Buffer Layer

Abstract

We investigated the dependence of strain relaxation and Sn precipitation on the thickness and the growth temperature of the Ge_1-xSn_x layer on a virtual Ge substrate. We found that the strain relaxation of the Ge_1-xSn_x layers is enhanced by increasing the thickness of the Ge_1-xSn_x layers. Additionally, the much higher degree of strain relaxation of 87% and higher Sn content of 6.8% were realized by lowering the growth temperature of the Ge_1-xSn_x layers. The low temperature growth probably enhances the introduction of point defects contributing to the creation of new misfit dislocations at the Ge_1-xSn_x/Ge interface. The Ge_1-xSn_x layer grown in this study has the potential to induce a tensile strain of 0.86% to the Ge layer.