NEW DEEP LEVEL LUMINESCENCE BANDS OBSERVED FROM BOTH A SIGE ALLOY LAYER AND SI/GE SUPERLATTICE STRUCTURES

Photoluminescence measurements have been made on Si/Ge short period superlattice structures grown on a SiGe alloy buffer layer and on a similar SiGe alloy layer without a superlattice. Using an InSb detector with a low energy cutoff at approximately 450 meV, the major luminescence features observed were two broad bands with maximum intensities at approximately 530 and approximately 720 meV. The luminescence intensity was found to vary with the superlattice composition but was substantially stronger for the SiGe alloy layer without a superlattice. We ascribe these luminescence features to defects in the SiGe alloy layers. This is supported by the observation that the introduction of deliberate copper contamination at 600-degrees-C dramatically increases the photoluminescence signal.