Terahertz plasmon photoresponse in a density modulated two-dimensional electron channel of a GaAs∕AlGaAs field-effect transistor

We present a theory of dc photoresponse, change in device conductance, at the plasmon resonance in the density modulated two-dimensional electron channel of the grating-gated GaAs∕AlGaAs field-effect transistor irradiated by an electromagnetic wave of terahertz frequency. An equilibrium density modulation is shown to give rise to a specific mechanism of photoresponse due to a plasma electrostriction effect. In strongly modulated systems, this effect dominates the photoresponse and results in a strong increase of the resonant peak amplitudes and photoresponse sign reversal dependent on the modulation depth and the equilibrium density profile. These results are in good qualitative agreement with recent experiments.