Article ID | Journal | Published Year | Pages | File Type |
---|---|---|---|---|
1528251 | Materials Chemistry and Physics | 2006 | 4 Pages |
Nanoindentation studies have been carried out on undoped and doped epitaxial GaN thin films with different thickness (1–4 μm) were grown epitaxially on c-plane sapphire substrate by metalorganic chemical vapor deposition (MOCVD). Multiple discontinuities (so-called ‘pop-in’ events) were observed in the load–indentation depth curve irrespective of the thickness as well as the doping condition. Atomic force microscopy (AFM) studies on the residual indentation impression revealed no micro-cracks even after the indentation beyond the critical depth. The physical mechanism responsible for the ‘pop-in’ was explained by the interaction of the deformed region, produced by the indenter tip, with the pre-existing threading dislocation in the epitaxial GaN thin films.