Effects of resonant interminiband Zener tunneling on the terahertz frequency radiation in GaAs/Al0.3Ga0.7As superlattices

The resonant interminiband Zener tunneling rate between two minibands in the process of terahertz (THz) radiation has been calculated with Kane model for two structures of GaAs/Al0.3Ga0.7As superlattices with high electric field. From the theoretical results, it is found that Zener tunneling rate not only increases with the applied electric field F but also is very dependent on the width of the minibands and that of the gap between minibands. Without any fitting parameter, the calculated results agree well with the experimental data reported by Hirakawa and his co-workers. The results we obtained in this work demonstrate that the measured broadening in the spectra of terahertz emission and the observed oscillation in the intensity curve of terahertz emission in the high electric field region are indeed due to the resonant interminiband Zener tunneling. The good agreement with experimental results also indicates that Kane theory is good enough to model Zener tunneling rate when F is below 90 kV/cm in the system we worked on.