Optical properties of delta doped InAs/GaAs0.88Sb0.12 structure for novel concept solar cells

We have investigated optical properties of InAs quantum dots (QDs) on GaAsSb barrier layer with different doping levels. In order to precisely control occupancy of subband levels in conduction band offset (CBO) in the material system, delta doping layer in the barrier was incorporated as an efficient carrier supply. Interband transitions between ground states or excited states were detected by implementing time-integrated photoluminescence (PL) whereas intersubband transitions have shown via Fourier transform-infrared spectroscopy (FT-IR) at room temperature. The results are compared and discussed with theoretical calculation based on k.p. method.