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Keywords:

  • InN;
  • wurtzite;
  • zincblende;
  • XRD

Abstract

InN epitaxial films are directly grown on sapphire (0001) substrates by using Pressurised-Reactor metalorganic vapour phase epitaxy (PR-MOVPE) system originally developed by ourselves. This system makes it possible to control the side wall of islands perpendicular to the substrate surface, which is important in the heteroepitaxial growth with large lattice-mismatch from the analogy of the GaN growth on sapphire substrates. This high pressure also leads to the growth at the higher temperature than that at the atmospheric pressure. In this paper, InN films are grown by PR-MOVPE at 2,400 Torr. Its polarity is nitrogen one, which has the superior efficiency to indium polarity in the capture of nitrogen at the growth front. To crystallographically identify films using the diffractions from sapphire (006), wurtzite (WZ) InN (002), zincblende (ZB) InN (111) and metallic indium (101), 2θ–ω scans and the pole figure measurements in X-ray diffraction are measured. From the pole figure measurements, the orientation and crystalline phases of grains in crystals are determined. The phase diagram between trimethylindium as an indium source flow rate and the growth temperature is drawn. The regions with pure WZ InN and with the incorporation of ZB phase and the metallic indium into WZ phase and the metal-indium are observed. It is also observed that the grains with WZ phase have c-axis normal to the (111) plane at the side wall of the ZB grains. Finally, the growth conditions for pure WZ InN make it clear by using PR-MOVPE. (© 2012 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim)