Dr Paddy K.L. Chan, Associate Professor of the Department of Mechanical Engineering, and his team have successfully developed staggered structure monolayer organic field effect transistors (OFETs) with a record low width normalized contact resistance down to 40 W-cm. This low contact resistance achievement is a critical cornerstone to miniaturize the OFETs for the advanced applications. The team has recently published this development in Advanced Materials.
Details of the publication:
Crystallized Monolayer Semiconductor for Ohmic Contact Resistance, High Intrinsic Gain, and High Current Density
Boyu Peng, Ke Cao, Albert Ho Yuen Lau, Ming Chen, Yang Lu, Paddy K. L. Chan
Article in Advanced Materials
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 cm2 V−1 s−1 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 DS = −1 V to V DS 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−1 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.