Terahertz conductivity and possible Bloch gain in semiconductor superlattices
We have investigated terahertz emission due to dynamical electron transport in wide-miniband GaAs/Al0.3Ga0.7As superlattices. By noting that the time-domain THz emission spectroscopy inherently measures the step-response of the electron system to the bias electric field, the obtained THz spectra were compared with the high-frequency conductivities predicted for miniband transport. Excellent agreem