Structural properties of aluminum–nitrogen films prepared at low temperature

Aluminum–nitrogen thin films have been obtained under well-controlled conditions by ion-beam-assisted deposition (IBAD). The films were deposited on crystalline silicon and sapphire substrates at relative low temperature (∼325 K). Taking advantage of the ion energy control provided by the IBAD technique, the films were prepared with N2+ ions with energies ranging from 100 to 300 eV. After deposition, the films were investigated by in situ x-ray photoelectron spectroscopy, ex situ by optical spectroscopy, and x-ray diffraction. Detailed Raman scattering measurements in the 100–2500 cm−1 wave number range were also performed revealing interesting features related to the atomic composition and structure of the films. The Raman data suggest that a misidentification of some vibration modes can lead to incorrect interpretations of the crystalline quality of aluminum–nitrogen films. Finally, the results indicate the suitability of IBAD to produce crystalline AlN films at considerably lower temperatures.