Optical anisotropy of InGaAs quantum dot arrays aligned along multiatomic steps on vicinal GaAs(111) B

摘要

The optical anisotropy of InGaAs quantum dot (QD) arrays on vicinal GaAs(111)B is investigated, in which the QDs are aligned and their shape is elongated along the [-110] direction. Polarised photoluminescence (PL) studies showed that the PL is preferentially polarized in the [-110] direction, where the polarization degree ρ is about 16.9%. Electronic states in InGaAs QD arrays are also examined theoretically to clarify how the optical anisotropy is affected by (1) the adjacent QDs, (2) the multiatomic steps on the substrate surface, and (3) the strain including the piezoelectric effect. By assuming the QD shape as a semi-elliptic cylindrical form, we calculate the electron and hole wave functions and evaluate the polarization degree ρ. We find that each of the three factors only slightly affects the optical anisotropy; the adjacent QDs, the multiatomic steps, and the strain increase the polarization degree ρ by 0.5, 2.3, and 1%, respectively. In contrast, the polarization degree ρ drastically increases by 8.9%, when all the three factors are simultaneously taken into account. We also compare the calculated results to the experimental data and show that all the effects of the three factors are important to explain the optical anisotropy of the InGaAs QD arrays.