tailieunhanh - báo cáo hóa học:" Berkovich Nanoindentation on AlN Thin Films"

Tuyển tập báo cáo các nghiên cứu khoa học quốc tế ngành hóa học dành cho các bạn yêu hóa học tham khảo đề tài: Berkovich Nanoindentation on AlN Thin Films | Nanoscale Res Lett 2010 5 935-940 DOI s11671-010-9582-5 NANO EXPRESS Berkovich Nanoindentation on AlN Thin Films Sheng-Rui Jian Guo-Ju Chen Ting-Chun Lin Received 6 January 2010 Accepted 16 March 2010 Published online 31 March 2010 The Author s 2010. This article is published with open access at Abstract Berkovich nanoindentation-induced mechanical deformation mechanisms of AlN thin films have been investigated by using atomic force microscopy AFM and cross-sectional transmission electron microscopy XTEM techniques. AlN thin films are deposited on the metalorganic chemical-vapor deposition MOCVD derived Si-doped 2 X 1017 cm 3 GaN template by using the helicon sputtering system. The XTEM samples were prepared by means of focused ion beam FIB milling to accurately position the cross-section of the nanoindented area. The hardness and Young s modulus of AlN thin films were measured by a Berkovich nanoindenter operated with the continuous contact stiffness measurements CSM option. The obtained values of the hardness and Young s modulus are 22 and 332 GPa respectively. The XTEM images taken in the vicinity regions just underneath the indenter tip revealed that the multiple pop-ins observed in the load-displacement curve during loading are due primarily to the activities of dislocation nucleation and propagation. The absence of discontinuities in the unloading segments of load-displacement curve suggests that no pressure-induced phase transition was involved. Results obtained in this study may also have technological implications for estimating possible mechanical damages induced by the fabrication processes of making the AlN-based devices. Keywords AlN Nanoindentation Focused ion beam Transmission electron microscopy . Jian . Chen . Lin Department of Materials Science and Engineering I-Shou University Kaohsiung 840 Taiwan ROC e-mail srjian@ Introduction The advent and development of microsystems and nanotechnology has its .