Enhanced Photon Extraction through Optimized Waveguide Geometry for Zincblende InAsP/InP Nanowire Quantum Dots...

InAs _x P_1-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 P_1-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 P_1-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.