Electronic structure of self-assembled InAs/InP quantum dots: A Comparison with self-assembled InAs/GaAs quantum dots

TL;DR

This study compares the electronic structures of InAs/InP and InAs/GaAs quantum dots, revealing significant differences in hole energy levels, shell structures, exciton energies, and polarization anisotropy due to material and lattice mismatch variations.

Contribution

It provides a detailed atomistic comparison of InAs/InP and InAs/GaAs quantum dots, highlighting key differences in electronic and optical properties.

Findings

InAs/InP dots have larger hole energy level spacing.

InAs/InP dots exhibit well-defined hole shell structures.

Exciton energies are about 200 meV lower in InAs/InP dots.

Abstract

We investigate the electronic structure of the InAs/InP quantum dots using an atomistic pseudopotential method and compare them to those of the InAs/GaAs QDs. We show that even though the InAs/InP and InAs/GaAs dots have the same dot material, their electronic structure differ significantly in certain aspects, especially for holes: (i) The hole levels have a much larger energy spacing in the InAs/InP dots than in the InAs/GaAs dots of corresponding size. (ii) Furthermore, in contrast with the InAs/GaAs dots, where the sizeable hole $p$, $d$ intra-shell level splitting smashes the energy level shell structure, the InAs/InP QDs have a well defined energy level shell structure with small $p$, $d$ level splitting, for holes. (iii) The fundamental exciton energies of the InAs/InP dots are calculated to be around 0.8 eV ($\sim$ 1.55 $\mu$m), about 200 meV lower than those of typical InAs/GaAs QDs, mainly due to the smaller lattice mismatch in the InAs/InP dots. (iii) The widths of the exciton $P$ shell and $D$ shell are much narrower in the InAs/InP dots than in the InAs/GaAs dots. (iv) The InAs/GaAs and InAs/InP dots have a reversed light polarization anisotropy along the [100] and [1$\bar{1}$0] directions.