Electronic Structure of (111)-Oriented Strained-Layer SiGe Superlattice

Using the first-principle self-consistent linear-muffin-tin-orbital method within the local density approximation, band structure of (111)-oriented strained-layer SiGe superlattice is studied. Three different ordered arrangements of atom layers (Si-GeΞSi-Ge Si-SiΞ Ge-Ge and SiΞSi-GeΞGe) are considered. Calcu- lated results indicate that (111)-oriented SiGe strained layer superlattices are semiconductive, with a band gap about 1.0eV. The first two superlattices are indirect band gap semiconductors, and the third one (SiΞSi-GeΞ Ge) is a direct band gap semiconductor. The influence of strain on the band structure is also investigated.