Effect of growth conditions on optical properties of CdSe/ZnSe single quantum dots

TL;DR

This study examines how growth conditions and substrate surface orientation influence the optical properties of CdSe/ZnSe quantum dots, revealing that vicinal surfaces suppress wetting layer emission and affect quantum dot size distribution.

Contribution

It provides new insights into how substrate vicinal surfaces and growth parameters affect the optical properties and size distribution of CdSe quantum dots.

Findings

Vicinal surfaces suppress wetting layer photoluminescence.

Different growth conditions lead to distinct quantum dot sizes.

Spatial resolution improvements reveal detailed PL lineshape evolution.

Abstract

In this work, we have investigated the optical properties of two samples of CdSe quantum dots by using submicro-photoluminescence spectroscopy. The effect of vicinal-surface GaAs substrates on their properties has been also assessed. The thinner sample, grown on a substrate with vicinal surface, includes only dots with a diameter of less than 10 nm (type A islands). Islands of an average diameter of about 16 nm (type B islands) that are related to a phase transition via a Stranski-Krastanow growth process are also distributed in the thicker sample grown on an oriented substrate. We have studied the evolution of lineshapes of PL spectra for these two samples by improving spatial resolution that was achieved using nanoapertures or mesa structures. It was found that the use of a substrate with the vicinal surface leads to the suppression of excitonic PL emitted from a wetting layer.