A theoretical analysis of the optical absorption properties in one-dimensional InAs/GaAs quantum dot superlattices

Abstract

We present theoretical investigations of miniband structures and optical properties of InAs/GaAs one-dimensional quantum dot superlattices (1D-QDSLs). The calculation is based on the multi-band k·p theory, including the conduction and valence band mixing effects, the strain effect, and the piezoelectric effect; all three effects have periodic boundary conditions. We find that both the electronic and optical properties of the 1D-QDSLs show unique states which are different from those of well known single quantum dots (QDs) or quantum wires. We predict that the optical absorption spectra of the 1D-QDSLs strongly depend on the inter-dot spacing because of the inter-dot carrier coupling and changing strain states, which strongly influence the conduction and valence band potentials. The inter-miniband transitions form the absorption bands. Those absorption bands can be tuned from almost continuous (closely stacked QD case) to spike-like shape (almost isolated QD case) by changing the inter-dot spacing. The polarization of the lowest absorption peak for the 1D-QDSLs changes from being parallel to the stacking direction to being perpendicular to the stacking direction as the inter-dot spacing increases. In the case of closely stacked QDs, in-plane anisotropy, especially [110] and [11¯0] directions also depend on the inter-dot spacing. Our findings and predictions will provide an additional degree of freedom for the design of QD-based optoelectronic devices.