標題: Cathodoluminescence and cross-sectional transmission electron microscopy studies for deformation behaviors of GaN thin films under Berkovich nanoindentation
作者: Jian, Sheng-Rui
Teng, I-Ju
Lu, Jian-Ming
材料科學與工程學系
Department of Materials Science and Engineering
關鍵字: GaN;MOCVD;nanoindentation;cathodoluminescence;focused ion beam;transmission electron microscopy
公開日期: 1-Apr-2008
摘要: In this study, details of Berkovich nanoindentation-induced mechanical deformation mechanisms of metal-organic chemical-vapor deposition-derived GaN thin films have been systematic investigated with the aid of the cathodoluminescence (CL) and the cross-sectional transmission electron microscopy (XTEM) techniques. The multiple "pop-in" events were observed in the load-displacement (P-h) curve and appeared to occur randomly by increasing the indentation load. These instabilities are attributed to the dislocation nucleation and propagation. The CL images of nanoindentation show very well-defined rosette structures with the hexagonal system and, clearly display the distribution of deformation-induced extended defects/dislocations which affect CL emission. By using focused ion beam milling to accurately position the cross-section of an indented area, XTEM results demonstrate that the major plastic deformation is taking place through the propagation of dislocations. The present observations are in support to the massive dislocations activities occurring underneath the indenter during the loading cycle. No evidence of either phase transformation or formation of micro-cracking was observed by means of scanning electron microscopy and XTEM observations. We also discuss how these features correlate with Berkovich nanoindentation produced defects/dislocations structures.
URI: http://dx.doi.org/10.1007/s11671-008-9130-8
http://hdl.handle.net/11536/9504
ISSN: 1931-7573
DOI: 10.1007/s11671-008-9130-8
期刊: NANOSCALE RESEARCH LETTERS
Volume: 3
Issue: 4
起始頁: 158
結束頁: 163
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