A Universal Method for Extracting and Quantitatively Analyzing Bias-Dependent Contact Resistance in Carbon-Nanotube Thin-Film Transistors

A single-device method is reported for extracting gate- and/or drain-voltage-dependent contact resistance of thin-film transistors (TFTs). An extended transition-voltage method is proposed and verified by experiments of all-carbon-nanotube thin-film transistors (ACNT-TFTs), which can extract gate- and/or drain-voltage-dependent contact resistance at source and drain independently. By measuring the output and transfer characteristics of a single-device and extracting the basic parameters with the aid of mature Y-function method, the contact resistance can be calculated directly. The results show that although a slight Schottky contact behavior is exhibited at very small drain voltages, good electrical contact characteristics can still be obtained in ACNT-TFTs, exhibiting quasi-Ohmic contacts. Compared with the existing single-device methods, this method is suitable for both Ohmic and Schottky contact scenarios without requiring a complex iteration process, which greatly improves the universality and efficiency of the contact resistance extraction. Besides, this method reveals the physical essence of the complex interface contacts and enables researchers to quantitatively analyze the contact performance, not only for network carbon nanotube TFTs but also for the other emerging transistors.