We study the acoustic-phonon transmission spectra in periodic and quasiperiodic (Fibonacci type) superlattices made up from the III-V nitride materials AlN and GaN. The phonon dynamics is described by a coupled elastic and electromagnetic equations within the static field approximation model,...

We have investigated electric field strengths in the Al<Subscript>x</Subscript>Ga<Subscript>1-x</Subscript>N layer, F<Subscript>AlGaN</Subscript>'s, of Al<Subscript>x</Subscript>Ga<Subscript>1-x</Subscript>N/GaN heterostructures with and without a GaN cap layer using photoreflectance (PR) spectroscopy. Franz-Keldysh oscillations (FKOs) from the Al<Subscript>x</Subscript>Ga<Subscript>1-x</Subscript>N layer are clearly observed in the PR spectra. It is...</subscript></subscript></subscript></subscript></subscript></subscript></subscript>