High Ge content SGOI substrates obtained by the Ge condensation technique: A template for growth of strained epitaxial Ge

In the first part of this work, the fabrication of silicon germanium-on-insulator substrates (SCOI) by the Ge condensation technique was studied. Ge atomic fractions as high as 93% have been obtained while maintaining nice structural properties of the films. We show that these layers exhibit a large compressive strain and that the strain can be lowered by introducing some annealing steps in argon ambient during the condensation. SGOI substrates with a Ge atomic fraction of 75% were subsequently used as template for the growth of strained epitaxial Ge layers. Because of the important strain in the SGOI, the temperature for the in-situ bake prior to the growth has to be carefully selected in order to avoid relaxation. Ge layers with compressive strain up to -1% and thicknesses up to 40 nm have been obtained. The crystal quality, roughness and thermal stability of the strained Ge layers were finally evaluated. (c) 2008 Elsevier B.V. All rights reserved