Microstructural evolution of a-plane GaN grown on a-plane SiC by metalorganic chemical vapor deposition


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Craven M., Wu F., Chakraborty A., Imer B., Mishra U., DenBaars S., ...More

APPLIED PHYSICS LETTERS, vol.84, no.8, pp.1281-1283, 2004 (Peer-Reviewed Journal) identifier identifier

  • Publication Type: Article / Article
  • Volume: 84 Issue: 8
  • Publication Date: 2004
  • Doi Number: 10.1063/1.1650545
  • Journal Name: APPLIED PHYSICS LETTERS
  • Journal Indexes: Science Citation Index Expanded, Scopus
  • Page Numbers: pp.1281-1283

Abstract

This letter describes the relationship between the morphological evolution of heteroepitaxial a-plane GaN films and the formation of the extended defect structure. The initial a-plane GaN growth on a-plane SiC substrates (via a high temperature AlN buffer layer) follows a Volmer-Weber growth mode. Consequently, the coalescence of three-dimensional (3D) islands generates threading dislocations which dominate the nonpolar GaN film's microstructure (3x10(10) cm(-2)). Exposed nitrogen-face surfaces, identified using x-ray diffraction measurements and convergent beam electron diffraction analysis, are present throughout the 3D growth and are the likely source of basal plane faulting (7x10(5) cm(-1)) within the film. Atomic force microscopy and scanning electron microscopy were used to image the morphological transition, which was correlated to changes in the a-GaN crystal tilt mosaic measured by x-ray rocking curves. (C) 2004 American Institute of Physics.