Peng Boyu, Cao Ke, Lau Albert Ho Yuen, Chen Ming, Lu Yang, Chan Paddy K L
Department of Mechanical Engineering, The University of Hong Kong, Pokfulam Road, Hong Kong.
Department of Mechanical Engineering, City University of Hong Kong, Kowloon, Hong Kong.
Adv Mater. 2020 Aug;32(34):e2002281. doi: 10.1002/adma.202002281. Epub 2020 Jul 14.
The contact resistance limits the downscaling and operating range of organic field-effect transistors (OFETs). Access resistance through multilayers of molecules and the nonideal metal/semiconductor interface are two major bottlenecks preventing the lowering of the contact resistance. In this work, monolayer (1L) organic crystals and nondestructive electrodes are utilized to overcome the abovementioned challenges. High intrinsic mobility of 12.5 cm V s and Ohmic contact resistance of 40 Ω cm are achieved. Unlike the thermionic emission in common Schottky contacts, the carriers are predominantly injected by field emission. The 1L-OFETs can operate linearly from V = -1 V to V as small as -0.1 mV. Thanks to the good pinch-off behavior brought by the monolayer semiconductor, the 1L-OFETs show high intrinsic gain at the saturation regime. At a high bias load, a maximum current density of 4.2 µA µm is achieved by the only molecular layer as the active channel, with a current saturation effect being observed. In addition to the low contact resistance and high-resolution lithography, it is suggested that the thermal management of high-mobility OFETs will be the next major challenge in achieving high-speed densely integrated flexible electronics.
接触电阻限制了有机场效应晶体管（OFET）的尺寸缩小和工作范围。通过多层分子的接入电阻以及不理想的金属/半导体界面是阻碍接触电阻降低的两个主要瓶颈。在这项工作中，利用单层（1L）有机晶体和无损电极来克服上述挑战。实现了12.5 cm² V⁻¹ s⁻¹ 的高本征迁移率和40 Ω cm的欧姆接触电阻。与普通肖特基接触中的热电子发射不同，载流子主要通过场发射注入。1L-OFET可以在从V = -1 V到低至-0.1 mV的V范围内线性工作。由于单层半导体带来的良好夹断行为，1L-OFET在饱和区表现出高本征增益。在高偏置负载下，仅作为有源沟道的单个分子层实现了4.2 μA µm⁻¹ 的最大电流密度，并观察到电流饱和效应。除了低接触电阻和高分辨率光刻外，还表明高迁移率OFET的热管理将是实现高速密集集成柔性电子学的下一个主要挑战。
