Acoustic phonon dynamics in strained cubic and hexagonal GaN/Al2O3 superlattices

摘要: We study the acoustic-phonon spectra in periodic and quasiperiodic (Fibonacci type) superlattices made up from III–V nitride materials (GaN) intercalated by sapphire (Al2O3). Due to misalignments between GaN layers that can lead threading dislocation densities as high 108-1010 cm-1, a significant lattice mismatch (~14%), phonon dynamics is described beyond continuum elastic model using coupled electromagnetic equations, stressing importance of piezoelectric polarization field strained condition. use transfer-matrix treatment simplify algebra, which would be otherwise quite complicated, allowing neat analytical expressions for dispersion relation. Furthermore, quantitative analysis localization magnitude allowed band widths phonon's spectra, well their scale law parametric spectrum singularities f(α), are presented discussed.