# Enhanced Photon Extraction through Optimized Waveguide Geometry for Zincblende InAsP/InP Nanowire Quantum Dots Emitting in the Telecom Range

## TL;DR

Researchers improved photon extraction from nanowire quantum dots by optimizing waveguide geometry, boosting emission intensity in the telecom range.

## Contribution

A novel method for creating InP waveguides around InAsP/InP nanowire quantum dots without SAE-VLS, enhancing telecom-range emission.

## Key findings

- Efficient InP waveguides were created around quantum dots without SAE-VLS.
- Optimized structures showed one order of magnitude higher emission intensity in the telecom range.
- Finite-difference time-domain simulations guided the geometry optimization.

## Abstract

InAs
x
P1–x
quantum dots (QDs) embedded in InP nanowires (NWs)
have recently
emerged as a promising platform, offering good control over QD size,
composition, and density through Au-catalyzed vapor–liquid–solid
(VLS) growth. A unique advantage of this approach is the possibility
of directly growing a waveguide around the QD, exploiting precise
control of NW radial growth. Usually, InAs
x
P1–x
NW-QDs are grown along the
<111> direction with a wurtzite (WZ) crystal phase, where waveguides
are typically realized using selective-area epitaxy combined with
VLS (SAE-VLS), requiring preparation and prepatterning of the substrates.
In the case of growth along the <100> direction, the growth
of
defect-free zincblende InAs
x
P1–x
NW-QDs occurs at larger catalyst nanoparticle diameter
compared to the WZ counterpart, with tunable emission over the telecom
bands. Here, we show that in this system, efficient InP waveguides
can be realized around the QDs without the need for SAE-VLS, solely
by balancing axial and radial growth contributions during the NW growth.
Employing the finite-difference time-domain simulations to optimize
the NW-QD geometries allows us to experimentally investigate the interrelation
between the growth parameters and the waveguide morphology. Microphotoluminescence
measurements of the optimized structures confirm their improved emission
properties and one order of magnitude enhanced QD emission intensity
in the telecom range.