Semiconductor superlattice diodes for detection of THz photons: The role of plasmon polariton excitation

The current (voltage) responsivity of the superlattice-based diode detectors in the terahertz frequency band which includes the region of the polar optical phonon frequencies has been analyzed theoretically. Within the framework of the equivalent circuit approach an electro-dynamical model which allows one to analyze the responsivity taking into account the plasmon polariton excitation both in the substrate and in the contact layers of the diodes has been suggested. It has been shown that the presence of the plasmon polariton excitation gives rise to strong features in the frequency dependence of the superlattice-based diodes responsivity, i.e. to the resonance dips and peaks at frequencies of hybridized plasmons and optical phonons. It has been suggested that by judicious engineering of the superlattice-based diodes it would be possible to enhance substantially their responsivity in the terahertz frequency band.