Polar Optical Phonons in AlN / GaN superlattice structures

Infrared reflection spectra of bulk semiconductors and superlattices can be predicted mathematically with optical phonon frequencies as some of the input variables. This method will be used to determine the polar longitudinal and transverse optical phonons modes and their corresponding energies that are present in AlN/GaN superlattices. Theoretical results will be compared to reflection experiments taken at a 75 incidence angle. Different AlN/GaN superlattice combinations will be studied to see if any pattern of phonon energies may arise. This outcome may prove useful in engineering phonons at specific frequencies. Furthermore, new phonons exist that are not at the energy levels present in bulk AlN and GaN. Phonon dispersion curve “folding” might prove useful to predict these new phonons. It will be determined whether this “folding” is a useful explanation for these new phonons, and if not, a new hypothesis will be made.