Observation of Direct Band Gap Properties in GenSim Strained-Layer Superlattices

Abstract
Photoluminescence and optical absorption measurements were carried out for Ge n Si m strained-layer superlattices grown by molecular beam epitaxy using a phase-locked epitaxy technique. A Ge4Si12 superlattice showed intense emission in the near-infrared region, and its absorption coefficient followed the (h v-E g)1/2 law, where h v is the energy of incident light and E g is the band gap energy. These results suggest that the Ge4Si12 sample has a direct band gap.