Tunnel field-effect transistors for sensitive terahertz detection

The rectification of electromagnetic waves to direct currents is a crucial process for energy harvesting, beyond-5G wireless communications, ultra-fast science, and observational astronomy. As the radiation frequency is raised to the sub-terahertz (THz) domain, ac-to-dc conversion by conventional electronics becomes challenging and requires alternative rectification protocols. Here, we address this challenge by tunnel field-effect transistors made of bilayer graphene (BLG). Taking advantage of BLG's electrically tunable band structure, we create a lateral tunnel junction and couple it to an antenna exposed to THz radiation. The incoming radiation is then down-converted by the tunnel junction nonlinearity, resulting in high responsivity (> 4kV/W) and low-noise (0.2pW/root Hz>) detection. We demonstrate how switching from intraband Ohmic to interband tunneling regime can raise detectors' responsivity by few orders of magnitude, in agreement with the developed theory. Our work demonstrates a potential application of tunnel transistors for THz detection and reveals BLG as a promising platform therefor.

Automated summary

The research addresses the challenge of ac-to-dc conversion in the sub-terahertz domain using tunnel field-effect transistors made of bilayer graphene. By creating a lateral tunnel junction and coupling it to an antenna exposed to THz radiation, high responsivity and low-noise detection are achieved. Switching from intraband Ohmic to interband tunneling regime significantly increases detectors' responsivity, showing the potential application of tunnel transistors for THz detection and the promising platform of BLG.