Droplet epitaxy of InAs/InP quantum dots via MOVPE by using an InGaAs interlayer

Elisa M Sala,Aristotelis Trapalis,Max Godsland,Young In Na,Jon Heffernan

doi:10.1088/1361-6528/ac3617

Abstract

InAs quantum dots (QDs) are grown on an In0.53Ga0.47As interlayer and embedded in an InP(100) matrix. They are fabricated via droplet epitaxy (DE) in a metal organic vapor phase epitaxy (MOVPE) reactor. Formation of metallic indium droplets on the In0.53Ga0.47As lattice-matched layer and their crystallization into QDs is demonstrated for the first time in MOVPE. The presence of the In0.53Ga0.47As layer prevents the formation of an unintentional non-stoichiometric 2D layer underneath and around the QDs, via suppression of the As-P exchange. The In0.53Ga0.47As layer affects the surface diffusion leading to a modified droplet crystallization process, where unexpectedly the size of the resulting QDs is found to be inversely proportional to the indium supply. Bright single dot emission is detected via micro-photoluminescence at low temperature, ranging from 1440 to 1600 nm, covering the technologically relevant telecom C-band. Transmission electron microscopy investigations reveal buried quantum dots with truncated pyramid shape without defects or dislocations.

Highlights

In the last decade, III–V quantum dots (QDs) fabricated by droplet epitaxy (DE) have attracted great interest due to their suitability for a wide range of applications, ranging from quantum photonics, where they can be employed as efficient quantum emitters of single and entangled photon pairs [1], to photodetectors [2], lasers [3], and solar cells [4]
We have investigated the growth of InAs QDs by droplet epitaxy in a metal organic vapor phase epitaxy (MOVPE) environment, for the first time on an In0.53Ga0.47As layer lattice-matched to InP
We have shown that the formation of indium droplets appears to be strongly affected by the presence of the interlayer, which modifies the indium surface diffusion

Summary

Introduction

III–V quantum dots (QDs) fabricated by droplet epitaxy (DE) have attracted great interest due to their suitability for a wide range of applications, ranging from quantum photonics, where they can be employed as efficient quantum emitters of single and entangled photon pairs [1], to photodetectors [2], lasers [3], and solar cells [4]. Very recently DE in combination with droplet etching of InAs/InP QDs emitting at the telecom C-band has been demonstrated [16] and [25], showing an additional and promising approach for nanostructure tuning during MOVPE growth. Such QDs can be employed as fundamental units for the fast-developing quantum information technology, for quantum networks [17,18,19]. Additional promising design strategies include, for instance, embedding InAs QDs in an InGaAs quantum well (QW) This allowed for an efficient post-growth tuning of the QD emission in the telecom O-band via the quantum-confined Stark effect in an entangled light emitting diode (ELED) [17]. This is the first report of the use of this approach with DE by MOVPE

Sample fabrication

Structural and optical investigation via AFM and PL

TEM investigations

Conclusions