High-Frequency Terahertz Rectification in Bilayer Graphene-Based Asymmetric Dual Grating Gates Field Effect Transistor

In this work, we report on terahertz rectification, up to 3.9 THz, using an asymmetric dual-grating gate graphene-based field effect transistor. The device, at 8K, was excited by terahertz radiation at three tones (2.5, 2.9 and 3.9 THz). A maximum of photocurrent, around 100 pA, was measured for the excitation at 3.9 THz. This intensity was increased by a factor of 3 when the bias of both top gates were of opposite sign. This behavior was explained as due to the ratchet effect induced by the asymmetric structure and terahertz radiation. The photocurrent remains unchanged when the modulation frequency was increased up to 2 kHz demonstrating the high speed response feature of the device.