High quality a-plane GaN films grown on cone-shaped patterned r-plane sapphire substrates

Y. Q. Sun, Z. H. Wu, J. Yin, Y. Y. Fang, H. Wang, C. H. Yu, Xiong Hui, C. Q. Chen, Q. Y. Wei, T. Li, K. W. Sun, Fernando Ponce

Research output: Contribution to journalArticlepeer-review

8 Scopus citations


Planar nonpolar (112̄0) a-plane GaN films have been grown by metalorganic chemical-vapor deposition directly on cone-shaped patterned r-plane sapphire substrates (PRSS) fabricated by dry etching. High-resolution X-ray diffractometers 2θ-ω scan confirmed that the films grown on PRSS are solely a-plane oriented, and the full width at half maximum values (FWHM) of the X-ray rocking curves for (112̄0) GaN along [0001]GaN and [11̄00]GaN were found to be 684 and 828″, respectively. As compared to the film grown on conventional r-plane sapphire substrate which typically has (112̄0) omega FWHM values of 900 and 2124″ along [0001]GaN and [11̄00]GaN respectively, the film grown on PRSS exhibits overall reduced omega FWHM values, and much smaller anisotropy behavior of crystallinity with respect to the in-plane orientation. The surface morphology is also improved by utilizing the PRSS technique. Cross-sectional transmission electron microscopy analysis shows that the density of threading dislocations has been greatly reduced from ~ 1.0 × 1010 cm - 2 above the flat sapphire regions to ~ 1.0 × 107 cm- 2 above the protruding cone patterns. The improvement of crystal quality and the increase of light extraction efficiency by using cone-shaped PRSS technique lead to a strong enhancement in the light emission of a-plane GaN films. These results indicate that growth of a-plane GaN films on cone-shaped PRSS shows promise for use in high-quality and high-cost-performance nonpolar GaN based devices.

Original languageEnglish (US)
Pages (from-to)2508-2512
Number of pages5
JournalThin Solid Films
Issue number8
StatePublished - Feb 1 2011


  • Cathodoluminescence
  • Metal-organic chemical vapor deposition
  • Nonpolar gallium nitride
  • Patterned sapphire substrate
  • Transmission electron microscopy
  • X-ray diffraction

ASJC Scopus subject areas

  • Electronic, Optical and Magnetic Materials
  • Surfaces and Interfaces
  • Surfaces, Coatings and Films
  • Metals and Alloys
  • Materials Chemistry


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