Inter-miniband resonant Zener tunneling in wide-miniband GaAs/Al0.3Ga0.7As superlattices investigated by THz emission spectroscopy

We have investigated the high-field transport in biased wide-miniband GaAs/Al0.3Ga0.7As superlattice (SL) diodes. Terahertz (THz) emission spectroscopy was performed on the emitted THz electromagnetic wave due to the electron motion in the SLs by using a bolometer as a wideband detector. With the increasing bias fields, two distinct regimes are observed in the bias-field dependence of the emitted THz intensity. These two regimes are attributed to the intra-miniband transport and inter-miniband Zener tunneling regimes, respectively. In the inter-miniband Zener tunneling regime, quasi-periodic structures are observed in the emitted THz intensity. The quasi-periodic peak structure is identified to be due to the resonant Zener tunneling between the Wannier–Stark ladders associated with the ground and the first-excited miniband. Resonant Zener tunneling up to the 9th-nearest-neighbor quantum wells was clearly resolved.