Structural and optical changes induced by incorporation of antimony into InAs/GaAs(001) quantum dots

TL;DR

This study investigates how incorporating antimony into InAs/GaAs quantum dots alters their structure and optical properties, revealing increased height, compositional segregation, and a significant redshift in photoluminescence.

Contribution

It provides the first detailed experimental analysis of Sb incorporation effects on the structural and optical characteristics of InAs/GaAs quantum dots.

Findings

Sb incorporation causes a compositional gradient within quantum dots.

Quantum-dot height increases with Sb flux exposure.

Photoluminescence shifts from 1.26 to 1.36 microns, with increased intensity.

Abstract

We present experimental evidence of Sb incorporation inside InAs/GaA(001) quantum dots exposed to an antimony flux immediately before capping with GaAs. The Sb composition profile inside the nanostructures as measured by cross-sectional scanning tunneling and electron transmission microscopies show two differentiated regions within the quantum dots, with an Sb rich alloy at the tip of the quantum dots. Atomic force microscopy and transmission electron microscopy micrographs show increased quantum-dot height with Sb flux exposure. The evolution of the reflection high-energy electron-diffraction pattern suggests that the increased height is due to changes in the quantum-dot capping process related to the presence of segregated Sb atoms. These structural and compositional changes result in a shift of the room-temperature photoluminescence emission from 1.26 to 1.36 microns accompanied by an order of magnitude increase in the room-temperature quantum-dot luminescence intensity.