Optical and electronic properties of low-density InAs/InP quantum dot-like structures devoted to single-photon emitters at telecom wavelengths

TL;DR

This study investigates low-density InAs/InP quantum dot-like structures emitting in the telecom wavelength range, focusing on their optical properties, growth methods, and potential for single-photon emission in quantum communication.

Contribution

It presents a comprehensive analysis of low-density InAs/InP QD-like structures, including growth via MOCVD, optical characterization, and theoretical modeling, advancing understanding of their properties for telecom applications.

Findings

Multiple PL peaks from flat QDs with monolayer height

Carrier redistribution observed with temperature-dependent PL

Theoretical models successfully reproduce emission energies and lifetimes

Abstract

Due to their band-structure and optical properties, InAs/InP quantum dots (QDs) constitute a promising system for single-photon generation at third telecom window of silica fibers and for applications in quantum communication networks. However, obtaining the necessary low in-plane density of emitters remains a challenge. Such structures are also still less explored than their InAs/GaAs counterparts regarding optical properties of confined carriers. Here, we report on the growth via metal-organic vapor phase epitaxy and investigation of low-density InAs/InP QD-like structures, emitting in the range of 1.2-1.7 ${\mu}$m, which includes the S, C, and L bands of the third optical window. We observe multiple photoluminescence (PL) peaks originating from flat QDs with height of small integer numbers of material monolayers. Temperature-dependent PL reveals redistribution of carriers between families of QDs. Via time-resolved PL, we obtain radiative lifetimes nearly independent of emission energy in contrast to previous reports on InAs/InP QDs, which we attribute to strongly height-dependent electron-hole correlations. Additionally, we observe neutral and charged exciton emission from spatially isolated emitters. Using the 8-band k${\cdot}$p model and configuration-interaction method, we successfully reproduce energies of emission lines, the dispersion of exciton lifetimes, carrier activation energies, as well as the biexciton binding energy, which allows for a detailed and comprehensive analysis of the underlying physics.