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Journal of Nanomaterials
Volume 2012, Article ID 914184, 6 pages
http://dx.doi.org/10.1155/2012/914184
Research Article

Indentation-Induced Mechanical Deformation Behaviors of AlN Thin Films Deposited on c-Plane Sapphire

1Department of Materials Science and Engineering, I-Shou University, Kaohsiung 84001, Taiwan
2Department of Electrophysics, National Chiao Tung University, Hsinchu 300, Taiwan

Received 16 November 2011; Accepted 13 January 2012

Academic Editor: Edward Andrew Payzant

Copyright © 2012 Sheng-Rui Jian and Jenh-Yih Juang. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.

Abstract

The mechanical properties and deformation behaviors of AlN thin films deposited on c-plane sapphire substrates by helicon sputtering method were determined using the Berkovich nanoindentation and cross-sectional transmission electron microscopy (XTEM). The load-displacement curves show the “pop-ins” phenomena during nanoindentation loading, indicative of the formation of slip bands caused by the propagation of dislocations. No evidence of nanoindentation-induced phase transformation or cracking patterns was observed up to the maximum load of 80 mN, from either XTEM or atomic force microscopy (AFM) of the mechanically deformed regions. Instead, XTEM revealed that the primary deformation mechanism in AlN thin films is via propagation of dislocations on both basal and pyramidal planes. Furthermore, the hardness and Young’s modulus of AlN thin films estimated using the continuous contact stiffness measurements (CSMs) mode provided with the nanoindenter are 16.2 GPa and 243.5 GPa, respectively.