Luminescence investigation on strained Si 1− xGe x/Si modulated quantum wells

Abstract

Luminescence characterization is presented on potential-modulated strained Si 1− x Ge x /Si(100) quantum wells. Interwell coupling was studied in a series of coupled quantum wells (CQW) with an intervening Si barrier for symmetric and asymmetric configurations. Systematic red shift of photoluminescence peak energy was observed in symmetric CQWs with decreasing Si barrier width centered at CQW. Interwell coupling was further evidenced in asymmetric CQWs luminescence as spectral dominance switch between the narrower and the wider wells, reflecting the tunneling-controlled carrier transfer. Evolution of Kronig-Penney superlattice state was observed as consistent luminescence peak shift with change in the structural parameters. Diffusion induced blue-shift of luminescence peak amounting to 22 meV was observed.