Dislocation generation at the coalescence of aluminum nitride lateral epitaxy on shallow-grooved sapphire substrates

J. Mei, Fernando Ponce, R. S Qhalid Fareed, J. W. Yang, M. Asif Khan

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The joining of defect-free AlN stripes is observed to trigger the generation of a large density of threading dislocations in the vicinity of the coalescence point. The AlN structure was grown by pulsed lateral epitaxy on shallow-grooved sapphire substrates. In the precoalescence stage, the dislocation density in the lateral epitaxial region (< 108 cm-2) is over two orders of magnitude less than in standard c -plane epitaxy. Basal-plane dislocations (b=a= 1 3 <11 2- 0>) are generated at the coalescence point as a result of relaxation of compressive stress that develops due to temperature gradients during growth. They bend toward the surface during the postcoalescence growth stage, leading to a high density of pure-edge threading dislocations in the lateral growth regions. Some threading dislocations form loops on prismatic planes in the crystal and the basal segments are observed to glide in the [0001] direction under the electron beam in the microscope.

Original languageEnglish (US)
Article number221909
JournalApplied Physics Letters
Issue number22
StatePublished - Jun 11 2007


ASJC Scopus subject areas

  • Physics and Astronomy (miscellaneous)

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