PHOTOLUMINESCENCE STUDY OF INITIAL INTERDIFFUSION OF SIGE SI QUANTUM-WELLS GROWN BY ULTRAHIGH VACUUM-CHEMICAL VAPOR-DEPOSITION/

SiGe quantum wells were grown at 525 degrees C using a commercially av ailable, ultrahigh vacuum-chemical vapor deposition system, in which t he purity of the material and quality of interfaces have already been demonstrated, Changes in photoluminescence line energies are monitored and the extent of interdiffusion in the wells during annealing is cal culated A strong initial enhancement of the diffusivity is observed in as-grown material. Material annealed using a two-step process in whic h strain and Ge peak concentrations are unchanged after the first (low temperature) step, shows a much lower interdiffusion during the secon d step. It is argued that strain alone cannot explain the enhanced int erdiffusion, which is, thus, attributed to grown-in, nonequilibrium po int defects. (C) 1996 American Institute of Physics.