THE EFFECTS OF INTERFACE DISORDER ON INTERBAND AND INTERSUBBAND TRANSITIONS IN GE-M-SI-N-GE-M STRUCTURES

Room-temperature photoluminescence has recently been reported by Gail et al (1995 Appl. Phys. Lett. 66 2978) in Ge-m-Si-n-Ge-m double-barrie r structures. Experimental evidence reveals that this luminescence is not due to electrons in the conduction band minima along the growth di rection, but to the four-fold degenerate bulklike minima. In this pape r we investigate the possibility that the observed spectra arise from the presence of interface disorder. We perform full-scale microscopic calculations on 3D supercells containing up to 16 000 atoms. We find t hat a very high level of disorder must be assumed in order to explain the observed results, and discuss alternative mechanisms.