Plasticity and optical properties of GaN under highly localized nanoindentation stress fields

P. G. Caldas, E. M. Silva, R. Prioli, J. Y. Huang, R. Juday, A. M. Fischer, Fernando Ponce

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28 Scopus citations


Nanoscale plasticity has been studied on (0001) GaN thin films, using tips with very small radius of curvature. Cross-section transmission electron microscopy images of the nanoindentations indicate that the primary slip systems are the pyramidal {11¯01}⟨112¯3⟩ and {112¯2}⟨112¯3⟩, followed by the basal {0002}⟨112¯0⟩. Incipient plasticity was observed to be initiated by metastable atomic-scale slip events that occur as the crystal conforms to the shape of the tip. Large volumetric material displacements along the {11¯01}⟨112¯3⟩ and {112¯2}⟨112¯3⟩ slip systems were observed at an average shear stress of 11 GPa. Hexagonal shaped nanoindentation impressions following the symmetry of GaN were observed, with material pile-up in the ⟨112¯0⟩ directions. Spatially resolved cathodoluminescence images were used to correlate the microstructure with the optical properties. A large number of non-radiative defects were observed directly below the indentation. Regions under tensile stress extending from the nanoindentation along ⟨112¯0⟩ directions were associated with the {0002}⟨112¯0⟩ slip.

Original languageEnglish (US)
Article number125105
JournalJournal of Applied Physics
Issue number12
StatePublished - Mar 28 2017

ASJC Scopus subject areas

  • General Physics and Astronomy


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