Local environment of Nitrogen in GaN{y}As{1-y} epilayers on GaAs (001) studied using X-ray absorption near edge spectroscopy

TL;DR

This study uses X-ray absorption near-edge spectroscopy to analyze the local nitrogen environment in GaNAs epilayers on GaAs, revealing insights into atomic arrangements and potential growth mechanisms.

Contribution

It combines experimental XANES measurements with density-functional theory predictions to accurately characterize nitrogen configurations in GaNAs alloys.

Findings

XANES accurately identifies nitrogen environments in GaN and GaNAs.

Nitrogen pairs are present and influence spectral features.

Molecular N₂ may play a role in epitaxial growth processes.

Abstract

X-ray absorption near-edge spectroscopy (XANES) is used to study the N environment in bulk GaN and in GaN{y}As{1-y} epilayers on GaAs (001), for y \~5%. Density-functional optimized structures were used to predict XANES via multiple-scattering theory. We obtain striking agreement for pure GaN. An alloy model with nitrogen pairs on Ga accurately predicts the threshold energy, the width of the XANES ``white line'', and features above threshold, for the given X-ray polarization. The presence of N-pairs may point to a role for molecular N_2 in epitaxial growth kinetics.