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ISRN Materials Science
Volume 2014 (2014), Article ID 521701, 10 pages
http://dx.doi.org/10.1155/2014/521701
Research Article

Stress and Grain Boundary Properties of GaN Films Prepared by Pulsed Laser Deposition Technique

1Department of Instrumentation Science, Jadavpur University, USIC Building, Calcutta 700 032, India
2UGC-DAE CSR, Kalpakkam Node, Kokilamedu 603104, India

Received 9 January 2014; Accepted 12 February 2014; Published 17 March 2014

Academic Editors: Z. Jiang and N. Martin

Copyright © 2014 D. Ghosh et al. 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

Polycrystalline gallium nitride films were successfully deposited on fused silica substrates by ablating a GaN target using pulsed Nd-YAG laser. Microstructural studies indicated an increase in the average crystallite size from ~8 nm to ~70 nm with the increase in substrate temperature from 300 K to 873 K during deposition. The films deposited here were nearly stoichiometric. XPS studies indicated two strong peaks located at ~1116.6 eV and ~395 eV for Ga2p3/2 and a N1s core-level peak, respectively. The films deposited at substrate temperature above 573 K are predominantly zinc blende in nature. PL spectra of the films deposited at higher temperatures were dominated by a strong peak at ~3.2 eV. FTIR spectra indicated a strong and broad absorption peak centered ~520 cm−1 with two shoulders at ~570 cm−1 and 584 cm−1. Characteristic Raman peak at ~531 cm−1 for the A1(TO) mode is observed for all the films. Grain boundary trap states varied between and  m−2, while barrier height at the grain boundaries varied between 12.4 meV and 37.14 meV. Stress in the films decreased with the increase in substrate temperature.