Crystal orientation by unpolarized infrared reflectivity application to aluminum nitride

We report on the application of Fourier transform infrared (FTIR) reflectivity as an approach to nondestructive optical technique for crystal orientation. Unpolarized FTIR reflectivity experiments were performed at near normal incidence on several facets of self-nucleated wurtzite aluminum nitride (AlN). The FTIR reflectivity spectra were carefully analyzed using the Kramers-Kronig technique. The orientation-dependent infrared reflectivity was described by a model which considers the infrared total response as being the combination of individual components of the reflected electric field. The AlN infrared active quasimodes were described by Loudon equations previously introduced for Raman active quasimodes in anisotropic materials. (C) 2007 American Institute of Physics.