Theory of electrons, holes and excitons in GaAs polytype quantum dots

TL;DR

This paper develops theoretical models for GaAs polytype quantum dots, highlighting spontaneous polarization's dominant role and predicting new phenomena like exciton tunability and state transitions relevant for optoelectronic applications.

Contribution

It introduces comprehensive multi-band Hamiltonians for GaAs quantum dots and predicts novel effects such as exciton wavelength control and state transitions.

Findings

Spontaneous polarization dominates quantum dot behavior.

Wide exciton wavelength and lifetime tunability is achievable.

Predicted phenomena include non-heavy hole ground states and exciton transitions.

Abstract

Single and multi-band (Burt-Foreman) k.p Hamiltonians for GaAs crystal phase quantum dots are developed and used to assess ongoing experimental activity on the role of such factors as quantum confinement, spontaneous polarization, valence band mixing and exciton Coulomb interaction. Spontaneous polarization is found to be a dominating term. Together with the control of dot thickness [Vainorious Nano Lett. 15, 2652 (2015)] it enables wide exciton wavelength and lifetime tunability. Several new phenomena are predicted for small diameter dots [Loitsch et al. Adv. Mater. 27, 2195 (2015)], including non-heavy hole ground state, strong hole spin admixture and a type-II to type-I exciton transition, which can be used to improve the absorption strength and reduce the radiative lifetime of GaAs polytypes.