Raman scattering studies on single-crystalline bulk AlN under high pressures

Abstract

We report on the Raman analysis of wurtzite single-crystalline bulk AlN under hydrostatic pressures up to 10 GPa. The pressure dependence of the AlN phonon frequencies was investigated. Mode Gru¨neisen parameters of 1.39, 1.57, 1.71, 0.93, and 1.26 were determined for the A₁ (TO), E₁ (TO), E₂ (high), A₁ (LO), and the quasi-longitudinal optical phonons, respectively. Recent theoretical calculations underestimate the pressure-induced frequency shift of the AlN phonons by about 20%–30%. Mode Gruneisen parameters of AlN were compared to those of GaN.