Quasistatic and dynamic interaction of high-frequency fields with miniband electrons in semiconductor superlattices

We studied the interaction of high-frequency (HF) fields with the miniband electrons in semiconductor superlattices that show (at room temperature) negative differential conductance. We observed a field-induced reduction of current through the superlattices, with a different bias dependence for fields below and above a characteristic frequency (1 THz). An analysis based on Bloch oscillations, indicating that the electrons relaxed within one cycle of the HF field (quasistatic interaction) or followed the field adiabatically (dynamic interaction), allows one to extract the intraminiband relaxation time ${(10\mathrm{}}^{-13}\mathrm{s}).\mathrm{}$