Thin Solid Films, Vol.684, 15-20, 2019
Characterization of highly textured piezoelectric AlN films obtained from aluminum and ammonium chloride by a simple vapor deposition process
We report a simple and efficient deposition technique for the growth of highly-textured AlN thin films. The proposed chloride-based chemical vapor deposition approach is based on widely available precursors and an unsophisticated experimental set-up. The films were characterized by electron microscopy, X-ray diffraction, Raman spectroscopy and cathodoluminescence. We studied the correlations between the deposition conditions and the properties of the resulting films, such as morphology, microstructure, features of the Raman spectra, and piezoelectric characteristics. In particular, we show that the minimum of the Raman bands A(1)(TO)/ E-2(h) intensity ratio, under excitation along c-axis, corresponds to the maximum of the piezoelectric coefficient. The films deposited under the optimized conditions are composed of well-aligned column-like crystallites. These films have a piezoelectric coefficient of 5.5-6.5 pC/N, which approaches the highest values reported for this material. The simplicity, efficiency and high quality of the resulting films make the proposed deposition approach highly interesting for a wide range of practical applications.
Keywords:Aluminum nitride;Thin films;Chemical vapor deposition;Texture;Raman spectroscopy;Piezoelectric modulus;Cathodoluminescence