Room-temperature Bloch oscillations and interminiband Zener tunneling in a GaAs-based narrow-minigap superlattice

We investigate peculiar Bloch oscillations and interminiband Zener tunneling in a GaAs-based narrow-minigap superlattice up to room temperature, by using terahertz emission spectroscopy under dc bias electric fields. The Bloch oscillations observed previously with a pi/2 phase shift at 10 K under relatively low bias fields are found to survive even at 300 K, where thermal energy kT exceeds the relevant minigap (k: Boltzmann constant, T: temperature). Furthermore, the interminiband Zener tunneling under high bias fields leads to a monocyclic terahertz signal with a temperature-dependent subsequent bumpy tail, indicating its occurrence at a few different occasions for Bloch oscillating electrons.