Mie-resonances, infrared emission and band gap of InN

TL;DR

This paper clarifies the true band gap of InN as wider than 0.7 eV, reveals that infrared emission at 0.7-0.8 eV originates from In aggregates, and discusses the misinterpretation of Mie resonances in previous studies.

Contribution

It provides direct measurements of InN's band gap and identifies the origin of infrared emission, correcting prior misconceptions caused by Mie resonances.

Findings

InN's true band gap is significantly wider than 0.7 eV.

Infrared emission at 0.7-0.8 eV is due to In aggregates, not the band gap.

Mie resonances have been misinterpreted as the band gap in past research.

Abstract

Mie resonances due to scattering/absorption of light in InN containing clusters of metallic In may have been erroneously interpreted as the infrared band gap absorption in tens of papers. Here we show by direct thermally detected optical absorption measurements that the true band gap of InN is markedly wider than currently accepted 0.7 eV. Micro-cathodoluminescence studies complemented by imaging of metallic In have shown that bright infrared emission at 0.7-0.8 eV arises from In aggregates, and is likely associated with surface states at the metal/InN interfaces.