Growth mechanisms of GaN/GaAs nanostructures by droplet epitaxy explained by complementary experiments and simulations

TL;DR

This study investigates the growth mechanisms of GaN nanostructures on GaAs substrates using droplet epitaxy, combining experiments and simulations to optimize nitridation conditions and achieve high-density zinc blende GaN nanodots.

Contribution

It provides a comprehensive analysis of GaN nanostructure growth via droplet epitaxy, integrating experimental techniques with kinetic Monte Carlo simulations for process optimization.

Findings

High-density (>10^11 cm^-2) GaN nanodots achieved at 300°C

Cubic zinc blende crystal structure confirmed by HRTEM

Temperature ramping improves nitridation and nanodot quality

Abstract

In this work, we present conception and study of gallium nitride (GaN) nanostructures on a gallium arsenide (GaAs) substrate with (111)A orientation. The nanostructures were designed by GaN droplet epitaxy and studied in-situ by X-ray photoelectron spectroscopy and ex-situ by atomic force microscopy, scanning electron microscopy and transmission electron microscopy. These studies were coupled with kinetic Monte Carlo simulations to precisely understand the phenomena occurring during the nitridation and to find the optimum conditions for complete nitridation of gallium droplets. The HRTEM observation showed a cubic (zinc blende) crystal structure of the GaN nanodots for a nitridation at 300{\deg}C. Ramping the temperature from 100{\deg}C to 350{\deg}C during droplet nitridation enabled to obtain a very high density (>1011cm-2) of GaN nanodots with the zinc blende crystallinity.