Direct evidence for carbon incorporation on the nitrogen site in AlN

TL;DR

This study provides direct experimental and theoretical evidence that carbon atoms substitute nitrogen sites in AlN, clarifying defect origins and linking them to observed optical and EPR properties.

Contribution

It offers the first combined EPR and first-principles analysis confirming carbon substitution on nitrogen sites in AlN, resolving previous ambiguities about defect origins.

Findings

Carbon substitutes nitrogen in AlN (C_N).

C_N explains previously attributed EPR spectra.

C_N presence correlates with 4.7 eV absorption in AlN.

Abstract

We use photo-electron paramagnetic resonance (EPR) measurements and first-principles calculations to identify and explain the properties of carbon in AlN. We present clear evidence for carbon substitution on the nitrogen site (C$_{\rm N}$). We also clarify the origin of a widely observed EPR spectra in AlN that, although often attributed to a deep donor defect, we demonstrate is surprisingly due to C$_{\rm N}$. Finally, we show the presence of C$_{\rm N}$ is consistent with the absorption spectra at 4.7 eV observed in AlN.