INTERBAND PHOTOLUMINESCENCE AND ELECTROLUMINESCENCE FROM SHORT-PERIODSI GE SUPERLATTICES/

We report on further investigations on the photoluminescence (PL) and electroluminescence (EL) properties of strained Si/Ge superlattices. T he band-gap PL from strain-adjusted Si(m)Ge(n) (m=9, 6, 3; n=6, 4, 2) superlattices has been studied as a function of applied external hydro static pressure. The superlattices used in these measurements are of i mproved quality in terms of dislocation density due to a thick, step-g raded Si1-xGex buffer layer, providing the strain symmetry. The no-pho non (NP) lines shift in all superlattices linearly to lower energies w ith applied hydrostatic pressure. The stress dependence was modeled us ing an approach based on deformation potentials and effective-mass the ory. Furthermore, we report on strong EL from a novel structure consis ting of only a 2-monolayer-thick Ge-layer embedded in bulk Si.