Variations in the apparent optical band-gap of RPE-CVD grown indium nitride thin films

Abstract

Indium nitride is a semiconducting material with a band-gap which is in current dispute. Although a ~ 0.75 eV band-gap was announced by some international groups in 2002 [1,2], it has since been shown that all the evidence for a ~ 0.75 eV band-gap is due to deep level defects [3, 4]. Despite this there still appears to be anomolous variations in the apparent bandgap for this material. The Macquarie University Low Temperature Nitride Film Growth Facility has recently grown some very high quality indium nitride thin films by remote plasma enhanced chemical vapour deposition (RPE-CVD). This material shows a variation in the apparent band-gap, as measured by optical absorption techniques, of 1.2 eV to 1.8 eV, dependent on the growth temperature and time. SIMS results measured by the ANSTO SIMS group show that the oxygen content of the films is low and that the variation in the apparent band-gap is not correlated to oxygen content. Other film properties will be described.