Vibration Spectra of Quasi-confined Optical Phonon Modes in an Asymmetric Wurtzite Al_xGa_(1-x)N/GaN/Al_yGa_(1-y)N Quantum Well

摘要

Based on the dielectric continuum model and Loudon's uniaxial crystal model, the properties of the quasi-confined (QC) optical phonon dispersions and the electron-QC phonons coupling functions in an asymmetric wurtzite quantum well (QW) are deduced via the method of electrostatic potential expanding. The present theoretical scheme can naturally reduce to the results in symmetric wurtzite QW once a set of symmetric structural parameters are chosen. Numerical calculations on an asymmetric AlN/GaN/Al_(0.15)Ga_(0.82)N wurtzite QW are performed. A detaiJed comparison with the symmetric wurtzite QW was also performed. The results show that the structural asymmetry of wurtzite QW changes greatly the dispersion frequencies and the electrostatic potential distributions of the QC optical phonon modes.