Nano Archive

Mechanical Deformation Behavior of Nonpolar GaN Thick Films by Berkovich Nanoindentation

Wei, Tongbo and Hu, Qiang and Duan, Ruifei and Wang, Junxi and Zeng, Yiping and Li, Jinmin and Yang, Yang and Liu, Yulong (2009) Mechanical Deformation Behavior of Nonpolar GaN Thick Films by Berkovich Nanoindentation. Nanoscale Research Letters, 4 (7). pp. 753-757.


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In this study, the deformation mechanisms of nonpolar GaN thick films grown on m-sapphire by hydride vapor phase epitaxy (HVPE) are investigated using nanoindentation with a Berkovich indenter, cathodoluminescence (CL), and Raman microscopy. Results show that nonpolar GaN is more susceptible to plastic deformation and has lower hardness than c-plane GaN. After indentation, lateral cracks emerge on the nonpolar GaN surface and preferentially propagate parallel to the <1120> orientation due to anisotropic defect-related stresses. Moreover, the quenching of CL luminescence can be observed to extend exclusively out from the center of the indentations along the <1120> orientation, a trend which is consistent with the evolution of cracks. The recrystallization process happens in the indented regions for the load of 500 mN. Raman area mapping indicates that the distribution of strain field coincides well with the profile of defect-expanded dark regions, while the enhanced compressive stress mainly concentrates in the facets of the indentation.

Item Type:Article
Subjects:Material Science > Nanochemistry
Material Science > Nanostructured materials
ID Code:5537
Deposited By:IoN
Deposited On:30 Jun 2009 11:36
Last Modified:30 Jun 2009 11:36

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