A study of indium nitride films grown under conditions resulting in apparent band-gaps from 0.7eV to 2.3eV

摘要

The band-gap of indium nitride has long been believed to be about 1.9eV with slight variations due to band-tailing in polycrystalline samples and degenerate doping.Recently,other values as low 0.7eV have apparently been observed.We have compared samples spanning this apparent range of band-gap using secondary ion mass spectroscopy (SIMS).X-ray Photoelectron Spectroscopy (XPS) and heavy ion elastic recoil detection analysis (ERDA),in conjunction with spectral optical density measurements.Once structural inhomogeneiteies are taken into account,we show that much of the conflicting data are compatible with direct photoionisation with a threshold energy of about 1.0eV.This feature was first reported in polycrystalline indium nitirde over 15 years ago and attributed to a |p>like defect state.We ask whether the feature may instead be a direct band-gap.