Growth of compositionally uniform $\mathrm{In}_{x}\mathrm{Ga}_{1-x}\mathrm{N}$ layers with low relaxation degree on GaN by molecular beam epitaxy

TL;DR

This study demonstrates the growth of uniform, low-relaxation InGaN layers with low dislocation densities on GaN substrates using plasma-assisted molecular beam epitaxy, highlighting their potential for nanowire fabrication.

Contribution

It presents a novel growth process yielding compositionally uniform InGaN layers with low strain relaxation and dislocation densities, suitable for advanced nanostructure applications.

Findings

Low strain relaxation (~10%) at x=0.12

Dislocation density of 1×10^9 cm^-2 at x=0.12

Uniform composition and narrow emission band

Abstract

500-nm-thick $\mathrm{In}_{x}\mathrm{Ga}_{1-x}\mathrm{N}$ layers with $x=$ 0.05-0.14 are grown using plasma-assisted molecular beam epitaxy, and their properties are assessed by a comprehensive analysis involving x-ray diffraction, secondary ion mass spectrometry, and cathodoluminescence as well as photoluminescence spectroscopy. We demonstrate low degrees of strain relaxation (10% for $x=0.12$), low threading dislocation densities ($\mathrm{1\times10^{9}\,cm^{-2}}$ for $x=0.12$), uniform composition both in the growth and lateral direction, and a narrow emission band. The unique sum of excellent materials properties make these layers an attractive basis for the top-down fabrication of ternary nanowires.