Infrared absorption at the LO phonon energy of metal/ semiconductor/metal composite materials

Interaction of a semiconductor surface or interface and p-polarized infrared light has been investigated from the viewpoint of THz application. In this study the electric dipole absorption at the resonant energy to a longitudinal optical phonon is clearly observed also for s-polarization for lateral Ti/GaN/Ti and Ti/GaAs/Ti stripe structures. Modification of permittivity is found by the analysis of Raman and IR spectra.