The effect of doping layers position on the heterojunction sharpness in (In,Al)As/AlAs quantum dots

TL;DR

This study investigates how the position of doping layers in (In,Al)As/AlAs quantum dot structures affects the sharpness of heterointerfaces, revealing that doping below QDs sharpens interfaces while doping above causes blurring.

Contribution

It demonstrates the impact of doped layer placement on heterointerface sharpness and exciton recombination dynamics in quantum dot structures, providing new insights into interface control.

Findings

Doping below QDs decelerates exciton recombination.

Doping above QDs does not affect exciton dynamics.

Interface diffuseness varies up to 5 lattice constants depending on doping position.

Abstract

Effect of doped layer placed in structures with indirect band-gap (In,Al)As/AlAs quantum dots (QDs) on heterointerface sharpness is investigated. We demonstrate that growth of n (p) doped layer below QDs sheet leads to pronounced deceleration (acceleration) for dynamics of exciton recombination (which is very sensitive to heterointeface structure in these QDs) in compare with the undoped structure. Opposite, the placing of the same doped layers above the QDs sheet does not effect on the exciton recombination dynamic at all. The experimental data are explained by increase (decrease) charged vacancy formation rate in the cation sublattice, that result in QD/matrix interface bluring (sharping), with the increases in the electron (hole) concentration at this heterointerface formation. The thicknesses of the diffuse layer on QD/matrix heterointerface estimated is in range from 0 up to 5 in the lattice constant depending on doped layer placing.