Relaxation of Strained Si1-XGeX by Dry Oxidation

Abstract

We investigated strain changes in Si1-XGeX layers on silicon substrates upon oxidation. We grew Si1-XGeX layers with different Ge fractions (x=0.15 and 0.3) on chemically cleaned silicon substrates by the UHV CVD process. Oxidation in a vertical furnace at 800C and 900C in an O2 gas ambient produced a silicon oxide layer and a silicon germanium layer that was richer in Ge-content than initial Si1-XGeX films. Initial compressively strained Si1-XGeX films are fully strained in this range of Ge fractions. The strain in the Ge- rich layer increased and then decreased as the oxidation temperature and time increased. In comparison, the strain of the remaining initial Si1-XGeX gradually relaxed with an increase in oxidation time and temperature. The relaxation occurred through the generation of dislocations and defects at the interface of the Si (100) substrate.