Effect of strain on the magneto-exciton groundstate in InP/GaInP quantum disks

TL;DR

This study investigates how strain and magnetic fields influence the groundstate properties of excitons in InP/GaInP quantum disks, revealing a transition from heavy-hole to light-hole states and comparing theoretical predictions with experimental data.

Contribution

It introduces a detailed analysis of strain-induced hole confinement transitions and magnetic field effects in quantum disks, highlighting a predicted hole wavefunction transition and discrepancies with experiments.

Findings

Strain causes heavy hole confinement inside the dot in thin, wide disks.

Increasing disk thickness induces a transition of the heavy hole to the boundary, forming a ring-like wavefunction.

Magnetic fields can trigger a heavy to light hole transition under certain parameters.

Abstract

The groundstate properties of an exciton in a self-assembled quantum disk are calculated in the presence of a perpendicular magnetic field. For sufficient wide and thin dots, the strain field leads to a confinement of the heavy hole within the dot and the system is type I, while the light hole is confined outside the dot and the system is type II. However, with increasing disk thickness, the strain induces a transition of the heavy hole from inside the disk towards the radial boundary outside the disk. For the exciton, we predict a heavy-hole to light-hole transition as a function of the disk thickness, i.e. forming a "ring-like" hole wavefunction. There is a range of parameters (radius and height of the disk) for which a magnetic field can induce such a heavy to light hole transition. The diamagnetic shift was compared with results from magneto-photoluminescence experiments, where we found an appreciable discrepancy. The origin of this discrepancy was investigated by varying the disk parameters, the valence band offset, and the effective masses.