Charge transport in monolayer and few-layer organic semiconductor field-effect transistors*

Like many other field effect transistor material systems, the contact resistance between the electrode and the active layer plays a dominating role in the performance of organic field effect transistors. In order to miniaturize the device and increase their density, a contact resistance down to 0.01 W-cm (100  W-mm) is highly desired. However, today’s devices are still orders of magnitudes higher than this desired value. In this talk, I will report the methodology of using ultrathin monolayer organic semiconductors with the van der Waals electrodes to address the contact resistance in OFETs. The transferred gold electrodes can eliminate the defects or trap states induced in the conventional vacuum deposition methods. By using the C10-DNTT as the channel material and solution shearing deposition method, we have achieved an intrinsic carrier mobility of 12 cm² V-s and a contact resistance of 40 W-cm. Furthermore, I will also demonstrate the individual contribution of the access resistance (R_A) and the interface resistance (R_INTF) in the total contact resistance of the OFETs. The electrical performance and the fabrication process of the monolayer OFETs will also be discuss in detail.