Effect of Low Temperature Ge Seed Layer and Post Thermal Annealing on Quality of Ge1-xSix (0.05 <= x <= 0.1) Graded Buffer Layers by UHV-CVD

Abstract

High crystal quality, smooth surface and fully relaxed Ge1-xSix (0.05 <= x <= 0.1) buffers are grown on 6 degrees-off (100) Si substrate by UHV-CVD. A low-temperature (LT) Ge seed layer is used to improve the quality of the Ge1-xSix buffers. In this study, the LT-Ge seed layer is deposited directly onto the Si substrate at a low temperature of 315 degrees C. After that, stress-free Si0.1Ge0.9 and Si0.05Ge0.95 layers are grown, respectively. An in-situ annealing process is also performed for the Si0.1Ge0.9/LT-Ge layers to increase the degree of relaxation. The total thickness of the epitaxial layer is 270 nm, with the average surface roughness at 0.6 nm.