Abstract
We study the vibrational spectrum of AlN grown on Si(111). The AlN was deposited using gas-source molecular beam epitaxy. Raman backscattering along the growth c axis and from a cleaved surface perpendicular to the wurtzite c direction allows us to determine the and phonon energies. For a 0.8-μm-thick AlN layer under a biaxial tensile stress of 0.6 GPa, these are 249.0, 653.6, 607.3, 884.5, and 666.5 , respectively. By combining the Raman and x-ray diffraction studies, the Raman stress factor of AlN is found to be for the phonon. This factor depends on published values of the elastic constants of AlN, as discussed in the text. The zero-stress energy is determined to be Fourier-transform infrared reflectance and absorption techniques allow us to measure the and phonon energies. The film thickness (from 0.06 to 1.0 μm) results in great differences in the reflectance spectra, which are well described by a model using damped Lorentzian oscillators taking into account the crystal anisotropy and the film thickness.
- Received 15 June 2000
DOI:https://doi.org/10.1103/PhysRevB.63.125313
©2001 American Physical Society