Synthesis of Nanostructured PLD AlN Films: XRD and Surface-Enhanced Raman Scattering Studies

Thin films of AlN on Si were fabricated by pulsed laser deposition in vacuum and in nitrogen ambient, and at laser repetition rate of 3 Hz or 10 Hz. The films were nanostructured according to the X-ray diffraction analysis and TEM imaging. Films deposited in vacuum were polycrystalline with hexagonal AlN phase and with columnar structure, while films deposited in nitrogen were predominantly amorphous with nanocrystallites inclusions. The Al-N phonon modes in the surface-enhanced Raman spectra were largely shifted due to stress in the films. Phonon mode of Al-O related to film surface oxidation is observed only for deposition at low pressures.