Electronic Structure of Si/Ge Heterostructures

The local density functional approach for calculating heterojunction valence band offsets is used to examine two aspects of the Si/Ge strained layer system. First, the strain in the Ge region for growth on Si(001) is considered. By minimizing the total energy with respect to the Ge strain parameter defined by a perpendicular sub (Ge)=(1+epsilon perpendicular)a sub (|Si), it is found theoretically that epsilon perpendicular = 0.063+-0.005 in agreement with more complete structural relaxation studies.