Optical and compositional properties of indium nitride grown by plasma assisted molecularbeam epitaxy

Abstract

Single-crystalline and polycrystalline indium nitride films have been grown on (0001)sapphire and silica glass using plasma assisted molecular beam epitaxy (PAMBE).Optical measurements on the films revealed a luminescence feature in the vicinity of0.8 eV for all films, both on sapphire and glass. No feature around 1.9 eV could beidentified above the background noise. To our knowledge this is the first reportof polycrystalline InN exhibiting the 0.8 eV feature. Ion beam analysis of thematerial could find no measurable oxygen contamination in the bulk of the films.These results, along with recent reports of blue shifting of the absorption onsetof InN films with increasing oxygen content, appear to point towards oxygencontamination as being the source of the previously reported higher bandgap.