Tunnel field-effect transistors for sensitive terahertz detection

TL;DR

This paper demonstrates that bilayer graphene tunnel field-effect transistors can effectively detect terahertz radiation by converting electromagnetic waves into direct current with high responsivity and low noise, advancing THz detection technology.

Contribution

The study introduces a novel THz detector based on bilayer graphene tunnel transistors, leveraging electrically tunable band structure for enhanced rectification performance.

Findings

High responsivity (> 4 kV/W) achieved in THz detection

Switching tunneling regimes significantly increases responsivity

BLG-based detectors show promise for sensitive THz applications

Abstract

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 (> 4 kV/W) and low-noise (0.2 pW/$\sqrt{\mathrm{Hz}}$}) 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.