Optical phonon lifetimes in sputtered AlN thin films.

We study the vibrational properties of AlN thin films deposited on silicon (100) substrates by the reactive DC-pulsed magnetron sputtering. The frequencies and lifetimes of the E₁(TO) and A₁(LO) optical phonons are calculated from Fourier transform infrared spectra using the factorized model of a damped oscillator. We analyze the structural properties by the x-ray diffraction technique to correlate the elongation of phonon lifetimes with increasing film thickness. The lifetimes of the phonon modes in AlN thin films are compared to the values in a single crystal. [ABSTRACT FROM AUTHOR]