Transit-time resonances enabling amplification and generation of terahertz radiation in periodic graphene p-i-n structures with the Zener-Klein interband tunneling

The Zener-Klein (ZK) interband tunneling in graphene layers (GLs) with the lateral n-i-n and p-i-n junctions results in the specific characteristics that can be used for the rectification, detection, amplification, and generation of the terahertz (THz) signals. The transit-time delay of the tunneling electrons and holes in the depletion regions leads to the phase shift between the THz current and THz voltage causing the negative dynamic conductance in a certain frequency range and resulting in the so-called transit-time (TT) instability. The combination of the ZK tunneling and the TT negative dynamic conductance enables resonant THz the amplification and generation of THz radiation. We propose the THz devices based on periodic cascade GL p-i-n structures exhibiting the TT resonances and evaluate their potential performance. Such structures can serve as THz amplifiers and, being placed in a Fabry-Pérot cavity, or coupled to a THz antenna or using a ring oscillator connection, as THz radiation sources.