A Practical Guide for X-Ray Diffraction Characterization of Ga(Al, In)N Alloys

TL;DR

This paper provides practical guidance on using x-ray diffraction to analyze Ga(Al, In)N alloys, addressing challenges in signal separation due to lattice mismatch and recommending optimal diffraction planes for accurate characterization.

Contribution

It offers a detailed comparison of diffraction planes and practical recommendations for x-ray diffraction analysis of Ga(Al, In)N alloys.

Findings

(0004) plane optimal for symmetric scans

(1015) plane optimal for asymmetric scans

Guidelines improve accuracy of strain and composition measurements

Abstract

Ga(In, Al)N alloys are used as an active layer or cladding layer in light emitting diodes and laser diodes. x-ray diffraction is extensively used to evaluate the crystalline quality, the chemical composition and the residual strain in Ga(Al,In)N thin films, which directly determine the emission wavelength and the device performance. Due to the minor mismatch in lattice parameters between Ga(Al, In)N alloy and a GaN virtual substrate, x-ray diffraction comes to a problem to separate the signal from Ga(Al,In)N alloy and GaN. We give a detailed comparison on different diffraction planes. In order to balance the intensity and peak separation between Ga(Al,In)N alloy and GaN, (0004) and (1015) planes make the best choice for symmetric scan and asymmetric scan, respectively.