Terahertz rectifying antennas (rectennas) couple micron-size antennas and high-speed diodes to convert the incident electro-magnetic radiation to useable DC power. At such frequencies, the device acting as the diode requires both a nonlinear electrical behavior and a very low parasitic capacitance. Due to their low-capacitance planar structure and high carrier mobility values, several graphene devices based on various rectification mechanisms have been previously proposed as the rectifying device in the terahertz range. In this paper, we report an asymmetric behavior in micrometer-scale rectangular CVD-grown graphene field-effect transistors (GFETs), both at 77 K and room temperature (295 K). The asymmetry with a measured I_ON/I_OFF ratio as high as 1.85 is shown to originate from the slight change in graphene conductivity induced by drain-gate voltage variations. This is confirmed by simulations using a simple drift-diffusion transport model. The conclusions can be directly applied to optimize diode-connected GFETs. This nonlinear effect may also be of interest for graphene interconnect considerations as well as circuit designs using GFETs.

太赫兹整流天线（rectennas）耦合微米级天线和高速二极管，以将入射的电磁辐射转换为可用的DC功率。在这样的频率下，充当二极管的器件既需要非线性电性能，又需要非常低的寄生电容。由于其低电容的平面结构和高的载流子迁移率值，先前已经提出了几种基于各种整流机制的石墨烯器件作为太赫兹范围内的整流器件。在本文中，我们报告了在77 K和室温（295 K）时，微米级矩形CVD生长的石墨烯场效应晶体管（GFET）的不对称行为。I _ON / I _OFF的不对称性高达1.85的比率显示出是由漏极-栅极电压变化引起的石墨烯电导率的轻微变化引起的。通过使用简单的漂移扩散传输模型进行的仿真证实了这一点。结论可以直接用于优化二极管连接的GFET。对于石墨烯互连以及使用GFET的电路设计，这种非线性效应也可能是令人感兴趣的。