Nanoscale Graphene‐Based Ballistic Rectifiers for Detection of High Terahertz Frequency Optical Signals

Graphene exhibits the longest carrier mean free path of any known electronic material, yet only a few device concepts have successfully leveraged this exceptional property. Here, we present a ballistic graphene rectifier capable of operating at frequencies up to 3 THz, significantly extending the limits of direct current (DC) generation through rectification in two‐dimensional materials. By engineering asymmetric nanojunction geometries in high‐mobility monolayer graphene encapsulated in hBN, we harness ballistic transport over >100 nm length scales to achieve efficient rectification without relying on p–n junctions or Schottky barriers. The devices exhibit robust rectified signals, with voltage responsivities of 100 V/W, 20 pW/Hz 1/2 noise‐equivalent powers at room temperature, and minimum detectable powers of 30 nW, outperforming conventional semiconductor‐based rectifiers in the same frequency range. Our results establish a new pathway for passive THz detection and signal processing, highlighting the potential of graphene nanodevices for next‐generation high‐frequency technologies.