Variation of Electronic Structure with C Content in Si1-x-yGexCy-5/Si(001) System

The electronic structures of strained Si1-x-yGexCy (y£0.09) alloys on Si(001) have been studied by the ab initio pseudopotential method within the local density functional theory. The variations of the minimum band gap, the valence-band offset and the strain properties in the heterojunction interface are calculated together with the average bond energy theory. It is found that the dependences of the minimum band gap and the valence-band offset on the alloy composition change around the point of zero lattice mismatch. A comparison between our theoretical results and the available experimental data indicates that some of the contradictions from different research groups can be reasonably explained.