High-quality strain-relaxed SiGe films grown with low temperature Si buffer

High-quality strain-relaxed SiGe templates with a low threading dislocation density and smooth surface are critical for device performance. In this wo rk, SiGe films on low temperature Si buffer layers were grown by solid-sour ce molecular beam epitaxy and characterized by atomic force microscope, dou ble-axis x-ray diffraction, photoluminescence spectroscopy, and Raman spect roscopy. Effects of the growth temperature and the thickness of the low tem perature Si buffer were studied. It was demonstrated that when using proper growth conditions for the low temperature Si buffer the Si buffer became t ensily strained and gave rise to the compliant effect. The lattice mismatch between the SiGe and the Si buffer layer was reduced. A 500 nm Si0.7Ge0.3 film with a low threading dislocation density as well as smooth surface was obtained by this method. (C) 2001 American Institute of Physics.