Abstract
The behavior of the E-2 and A(1)(LO) optical phonons of hexagonal indium nitride under hydrostatic pressure was studied using Raman spectroscopy. Linear pressure coefficients and the corresponding Gruneisen parameters for both modes were determined for the wurtzite structure up to 11.6 GPa, close to the starting pressure of the hexagonal to rocksalt phase transition of InN. Raman spectra acquired within the 11.6 to 13.2 GPa pressure range suggest that wurtzite InN undergoes a gradual phase transition, and the reverse transformation exhibits a strong hysteresis effect during the downstroke.