PHOTOLUMINESCENCE STUDY OF SI1-XGEX SI SURFACE QUANTUM-WELLS/

We report a photoluminescence (PL) study of Si1-xGex/Si surface quantu m wells (SFQWs). The PL peak energies are found to be affected by stra in relaxation in Ge-rich SFQWs while a PL energy lowering was observed for x less than or equal to 0.47 as compared to buried quantum wells capped with Si. Exciton localization in the lateral direction is sugge sted to be the dominant PL mechanism in SFQWs rather than perpendicula r confinement effects that are expected for SFQWs. PL degradation and a spectral dominance switch over to newly developing lower energy peak s were clearly observed after prolonged air exposure. (C) 1997 America n institute of Physics.