Phonon transport unveils the prevalent point defects in GaN

TL;DR

This paper uses thermal transport modeling to identify and quantify point defects in GaN, revealing the prevalence of gallium vacancies and their complexation with hydrogen, and demonstrating the predictive power of ab initio phonon transport methods.

Contribution

It introduces an unconventional approach using phonon transport modeling to determine defect types and concentrations in GaN, providing conclusive evidence for vacancy-hydrogen complexes.

Findings

Gallium vacancies can be complexed with hydrogen in GaN.

Thermal conductivity modeling aligns with experimental data.

Ab initio phonon transport effectively quantifies semiconductor defects.

Abstract

Determining the types and concentrations of vacancies present in intentionally doped GaN is a notoriously difficult and long-debated problem. Here we use an unconventional approach, based on thermal transport modeling, to determine the prevalence of vacancies in previous measurements. This allows us to provide conclusive evidence of the recent hypothesis that gallium vacancies in ammonothermally grown samples can be complexed with hydrogen. Our calculations for O-doped and Mg-O co-doped samples yield a consistent picture interlinking dopant and vacancy concentration, carrier density, and thermal conductivity, in excellent agreement with experimental measurements. These results also highlight the predictive power of ab initio phonon transport modeling, and its value for understanding and quantifying defects in semiconductors.