Abstract :
Optical anisotropy in type-II quantum wells (QWs) on high-index substrates is studied theoretically. We analyze GaAs1−XSbX/GaAs type-II QWs and calculate the degree ρ of polarization. Compared to type-I QWs, the optical anisotropy is enhanced in the type-II QW due to the spatial overlap of holes in the QW and electrons outside. We also evaluate ρ in the QW as a function of the diffusion length to clarify how the optical anisotropy is affected by the interface grading due to the Sb/As interdiffusion. In an initial stage of grading where the diffusion process tends to increase the effective size of the repulsive potential, the electron is more repelled by the QW, leading to an increase in ρ. In later stages, however, the hole confinement and the electron repulsion by the QW both weaken, leading to a decrease in ρ. We also examine the effect of excited carrier concentration on the optical anisotropy in the type-II QW.
