OPTICAL-SPECTRA AND RECOMBINATION IN SIGE SI HETEROSTRUCTURES FOR INFRARED APPLICATIONS/

We report a study of absorption and Auger recombination in p-type SiGe /Si heterostructures in which the Ge concentration has been varied fro m 15% to 50%, with a view to assessing the optimum condition fur infra red applications in the 3-5 and 8-15 mu m ranges. Our results have bee n obtained by full scale microscopic calculations in which the effects of the crystal potential, doping and well width upon the strength and frequency of the absorption response have been considered. We present a detailed comparison of our theoretical optical lineshapes with thos e obtained in recent experiments for both parallel and normal incident Light. Finally, we identify the band structure properties that are ne cessary for the reduction of Auger recombination in systems of practic al importance and present preliminary results for the Auger rates in t hese structures.