Photoluminescence within Crystalline-Si/SiO_2 Single Quantum Wells

摘要

Ultrathin single quantum wells of crystalline silicon (c-Si) confined by SiO_2 have been prepared by chemical and thermal processing of silicon-on-insulator wafers. The photoluminescence (PL) produced by these nanometer-thick single wells contains two bands: one exhibits a peak energy of ~1.8 eV, while the second increases rapidly in peak energy with decreasing c-Si layer thickness. Comparison with theories based on self-consistent first-principles calculations shows that the increase in PL peak energy of the second band is consistent with that predicted for the c-Si energy gap of such wells. It also agrees with the measured band gap variation. The ~1.8 eV PL band is attributed to the recombination of electron-hole pairs confined at the c-Si/SiO_2 interface.