Peculiarities of amplitude and phase spectra of semiconductor structures in THz frequency range

We have reviewed main peculiarities of amplitude and phase transmission/reflection spectra of different model semiconductor structures, including bare dielectric substrate, thin conductive layer placed between two dielectric media, thin conductive layer on dielectric substrate and hybrid plasmonic structures with thin conductive layer under metallic grating. The analysis has been performed using the analytical expressions obtained as a result of solving the Maxwell equations at normal incidence of plane electromagnetic waves. We have shown that specific behavior of the amplitude and phase spectra in THz frequency range can be used to determine basic electric parameters of electron gas, including electron concentration and electron mobility, in the framework of advanced THz time-domain measurements. Finally, we proposed efficient, electrically-controllable THz phase modulator based on effect of two-dimensional plasmon resonances in hybrid plasmonic structure with a spatially modulated electron concentration in a thin conductive layer.