Phonon-Polariton Excitations in MgZnO/6H-SiC Structures

Abstract

Specular infrared reflection spectra in the range of “residual rays” of the film and the substrate and in the case of the E⊥c orientation of the electric field have been simulated for the first time for thin MgxZn1−xO films deposited on optically anisotropic 6H-SiC substrates. The simulation was carried out making use of self-consistent parameters obtained earlier for magnesium oxide, zinc oxide, and silicon carbide single crystals. The film thickness and the Mg content x in the film are demonstrated to considerably distort the reflection spectra and to change the reflectivity of the MgxZn1−xO/6H-SiC structure. Using the Kramers–Kronig relation, the spectral intervals, where the reflectivity is sensitive to the film thickness and to the doping levels of the film and the substrate, are determined. The main attention is paid to analyze results obtained for x = 0.2. The existence of surface polaritons in such structures is theoretically demonstrated for the first time, and the attenuated total reflectance surface I(v)/I0(v) is plotted as a three-dimensional representation of the structure transmittance dependence on the radiation frequency and the incidence angle. A possibility to study the resonant interaction of optical phonons with plasmons in the film and the substrate is demonstrated.