Effect of Oxygen and Aluminium Incorporation on Local Structure of GaN Nanowires: Insight from Extended X-ray Absorption Fine Structure Analysis

TL;DR

This study investigates how oxygen and aluminium doping affect the local atomic structure of GaN nanowires using EXAFS, DFT, and Raman spectroscopy, revealing bond length changes and lattice site preferences.

Contribution

It provides new insights into the local structural modifications caused by oxygen and aluminium incorporation in GaN nanowires, aiding in ternary alloy formation understanding.

Findings

Oxygen doping causes bond length contraction along crystal axes.

Al incorporation alters the local tetrahedral structure of GaN.

EXAFS analysis aligns with Raman spectroscopy observations.

Abstract

A thorough investigation of local structure, influencing macroscopic properties of the solid is of potential interest. We investigated the local structure of GaN nanowires (NWs) with different native defect concentration synthesized by the chemical vapor deposition technique. Extended X-ray absorption fine structure (EXAFS) analysis and semi-empirical and the density functional theory (DFT) calculations were used to address the effect of dopant incorporation along with other defects on the co-ordination number and bond length values. The decrease of the bond length values along preferential crystal axes in the local tetrahedral structure of GaN emphasizes the preferred lattice site for oxygen doping. The preferential bond length contraction is corroborated by the simulations. We have also studied the impact on the local atomic configuration of GaN NWs with Al incorporation. AlxGa1-xN NWs are synthesized via novel ion beam techniques of ion beam mixing and post-irradiation diffusion process. The change in the local tetrahedral structure of GaN with Al incorporation is investigated by EXAFS analysis. The analysis provides a clear understanding of choosing a suitable process for ternary III-nitride random alloy formation. The local structure study with the EXAFS analysis is corroborated with the observed macroscopic properties studied using Raman spectroscopy.