High-pressure Raman scattering of CdO thin films grown by metal-organic vapor phase epitaxy

Abstract

We have performed Raman-scattering measurements under high hydrostatic pressure on CdO thin films grown by metal-organic vapor phase epitaxy on sapphire substrates. The pressure dependence of the second-order Raman bands is discussed in terms of ab initio lattice-dynamical calculations, which allow us to obtain mode Grüneisen parameters for the zone-center TO and LO modes of CdO. Our experiments and calculations suggest that at low pressures (<4 GPa) the Raman spectra are dominated by second-order modes, while at higher pressures (>4 GPa) the spectra mainly display contributions from disorder-activated first-order modes.