UNIVERSITY OF BUCHAREST
FACULTY OF PHYSICS

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Conference: Bucharest University Faculty of Physics 2011 Meeting


Section: Solid State Physics and Materials Science


Title:
Thermal properties of small diameter AlN nanowires in the vicinity of a structural phase transition


Authors:
T.L. Mitran, A. Nicolaev, G.A. Nemnes, L. Ion, S. Antohe


Affiliation:
University of Bucharest, Faculty of Physics, 405 Atomistilor, POB MG-11, 077125, Magurele-Ilfov, Romania


E-mail
tudor@solid.fizica.unibuc.ro


Keywords:


Abstract:
Wide band-gap semiconductors are being considered as possible solutions for the next generation of electronic and optoelectronic devices that are required to endure harsher environments or function at higher electronic or optic frequencies than current technology allows. The field of use for such materials can be widened even further by modeling them into nanostructures with tunable shape, size and chemical composition. Amongst the possible uses are those of: chemical sensors [1], electronic, optoelectronic, and field emission nano-devices [2]. One material that is well suited for such applications and is worth further investigation is AlN, not only because of its intrinsic physical properties but also because its successful synthetisation into low dimensional structures has already been proven [3,4,5]. In this study we obtain the relaxed configuration, phononic dispersions and density of states, specific heat, and thermal transmission coefficient of some selected AlN nanowires with diameters in the order of a few nm. As indicated in [6], such structures experience a dimension-dependent phase transition from their wurtzite configuration with [001] orientation along the nanowire axis to a graphene-like structure with stacked planes along the [001] axis. In our study we have pointed out that this transition can be induced by external stress. The dependence of the thermal properties of such structures with externally applied forces are of practical importance since electronics suffer from tensional or compressional stress caused by either thermal or mechanical fluctuations. If nanowires similar to the ones presented here would be contained in actual devices (for example, if they would be used as bridging elements between microscopic contacts), would suffer a dramatic change in properties when acted upon by physically plausible forces in the order of few nN. [1] Zhen Zhou, Jijun Zhao, Yongsheng Chen, Paul von Ragué Schleyer and Zhongfang Chen, Nanotechnology 18, 424023 (2007) [2] Y. B. Tang, H. T. Cong, Z. G. Zhao, and H. M. Cheng, Appl. Phys. Lett. 86,153104 (2005) [3] G. R. Yazdi, M. Syvajarvi, and R. Yakimova, Appl. Phys. Lett. 90, 123103 (2007) [4] L.H. Shen, X.F. Li, J. Zhang, Y.M. Ma, F. Wang, G. Peng, Q.L. Cui, G.T. Zou,Appl. Phys. A 84, 73-75 (2006) [5] Qiang Wu, Zheng Hu, Xizhang Wang, Yemin Hu, Yajun Tian, Yi Chen, Diam. and Rel.Mat. 13, 38-41 (2004) [6] Yelong Wu, Guangde Chen, Honggang Ye, Youzhang Zhu, and Su-Huai Wei, Appl. Phys.Lett. 94, 253101 (2009)