Surface plasmon resonance behaviors of a highly Ga-doped ZnO nano-grating structure

Abstract

Surface nano-gratings of different periods are fabricated on a Ga-doped ZnO (GaZnO) thin film with a high electron concentration for the study of their surface plasmon (SP) resonance behaviors in the near-infrared range. The dispersion curve of the surface plasmon polariton (SPP) based on the ellipsometry measurement of the GaZnO dielectric constant helps in designing the grating period for effective SPP excitation. Spectral depressions of grating reflection under certain incident polarization conditions, corresponding to SP resonance features, are observed in the wavelength range between 1400 and 2200 nm. From the numerical simulation of light scattering from a GaZnO grating structure based on the measured dielectric constant and the fitted Drude model, we can identify either SPP or localized SP modes among the observed SP resonance features. Essentially, it is difficult to excite below 1600 nm SPP at an air/GaZnO interface due to its lossy nature. The potential application of SP resonance on GaZnO is evaluated.