Structural, electrical and optical studies on the effects of rapid thermal processing on silicon-germanium-carbon films

Abstract

A structural, electrical and optical study on the effect of rapid thermal processing on strained Si1i?-xGex, Si1i?-xi?-yGexCy alloys was reported in this thesis. Structural characterization showed that, when annealed at temperature higher than 900i??C, substitutional C changed to more stable phase of SiC, which was responsible for the observed strain variation. But the chance of forming SiC precipitate in oxidation case was greatly reduced due to CO or CO2 outdiffusion. As far as Ge was concerned, similar to the oxidation of Si1i?-xGex, direct oxidation of Si1i?-xi?-yGexCy alloy led to Ge pilei?-up at oxide/epitaxial-layer interface. Electrical characterization on MOS capacitors demonstrated rather poor interface properties and substrate degradation. Ge pile-up and C residues were the main causes of the observed fixed charge and interface state density, while SiC precipitate was related to the substrate defect formation. The optical results confirmed the substitutional C loss and the Ge pile-up at the oxide/epitaxiala??layer interface.