Ultrasmall In(Ga)As Quantum Dots Grown on Strained GaxIn1-xP Layers

TL;DR

This study demonstrates the growth of ultrasmall In(Ga)As quantum dots on strained GaxIn1-xP layers, revealing their discrete height distribution, spectral properties, and Ga diffusion effects, supported by experimental and theoretical analysis.

Contribution

It introduces a method to grow ultrasmall quantum dots on strained layers and characterizes their properties with combined experimental and modeling approaches.

Findings

Quantum dots have vertical dimensions of 2-10 monolayers.

Spectral peaks correspond to discrete dot heights.

Ga diffusion into quantum dots is quantified.

Abstract

InAs self-assembled quantum dots were grown on strained layers of GaxIn1-xP (0 < x < 0.3) on InP substrates. We show that the quantum dots have narrow vertical dimensions, ranging between 2 to 10 monolayers only. The dot layer photoluminescence spectrum is composed of distinct spectral peaks, resulting from the discrete distribution of the dot heights. The dot height distribution depends on the total amount of InAs deposited and on the Ga content of the strained GaxIn1-xP layer underneath. Our experimental results are corroborated by an 8 band k(dot)P model calculations. In particular, we identify and quantify the diffusion of Ga from the GaxIn1-xP layer into the quantum dots.