Optical and structural characterization of Si/SiGe heterostructures grown by RTCVD

The effect of interface potential fluctuations of a Si/SiGe multiple quantu m well structure upon the low temperature exciton luminescence is studied. A possible exciton localization at such potential fluctuations, with a late ral period of 9-12 nm, is observed as a blue shift with increasing excitati on power in the low temperature photoluminescence. Moreover, annealing the sample at temperatures well below the growth temperature leads to the forma tion of striations with a period of several micrometers along the 011 direc tion. To clarify whether or not a metallic decoration of misfit dislocation s is needed to observe D1-line photoluminescence (PL) emission, annealing w as performed in two different ways. Only in the case of annealing in direct contact with a metal, D1-line emission was observed in photoluminescence e xperiments. (C) 2000 Elsevier Science S.A. All rights reserved.