Theoretical Studies on Optical Phonon and Surface Phonon Polariton of Wurtzite AlInN Alloys

Abstract

The lattice vibrational properties of wurtzite ternary mixed crystal aluminium indium nitride (AlxIn1-xN) are investigated thoroughly using modified random element iso-displacement (MREI) model and Born-Huang procedure. MREI model, which considers the nearest neighbour interactions, is used to predict the composition dependence of longitudinal and transverse optical phonon frequencies. For AlxIn1-xN alloy, oscillator strength of its weak mode is sufficiently significant for composition range of 0 < x < 0.4. As a result, AlxIn1-xN alloy is deduced to exhibit mixed-mode behaviour. Finally, the calculated dielectric functions for the entire composition range (0 < x < 1) are used to simulate the surface phonon polariton characteristics of the AlxIn1-xN alloy.