InP acoustic cavity phonon spectra probed by Raman Scattering

We present a Raman scattering study of the phonon spectra of an InP acoustic phonon cavity. Ga0.47In0.53As/Al0.48In0.52As phonon mirrors, lattice matched with InP, are used for the acoustic phonon confinement. High resolution backscattering Raman measurements evidence a doubling of the folded acoustic phonon spectra. Photoelastic model calculations, with a continuum model for the acoustic vibrations that include the appropriate boundary conditions at the structure-air interface, are presented to interpret the data. The Raman spectra are shown to be highly sensitive to the details of the structure, thus allowing a proper characterization of the device. We found that the InP cavity longitudinal optical phonon linewidth is increased by residual strain and disorder, but that the anharmonic contribution is substantial at room temperature. This implies that acoustic cavities could be used for optical phonon decay time engineering in InP optoelectronic devices.