近期，本课题组张敏老师和博士生刘德行分别以通讯作者和第一作者在Advanced Electronic Materials （PHYSICS, APPLIED, Q1）期刊上发表了题为“A Universal Method for Extracting and Quantitatively Analyzing Bias-Dependent Contact Resistance in Carbon-Nanotube Thin-Film Transistors” 的研究论文。
近年来，在智能穿戴、人机交互、虚拟现实和未来医疗技术等应用的推动下，基于软性材料的具有优异性能的新兴柔性电子产品具有很大的需求量。与传统的硅基场效应晶体管相比，这些新兴的柔性晶体管的接触特性非常关键，但由于金属/半导体界面上存在相当复杂的物理过程，直到今天未被很好地理解。在这种情况下，接触电阻通常依赖于偏置电压以及沟道缩放，这大大降低了此前报道的分析接触电阻方法的适用性。因此，迫切需要一种合适的偏压依赖的接触电阻提取方法，以更好地理解金属/半导体接触机制，并进一步优化新兴晶体管和电路的性能。
碳纳米管薄膜晶体管作为柔性晶体管的潜在解决方案，其为进一步推进超柔电子技术提供了更多可能性。在这项工作中，我们报告了一种可以提取碳纳米管薄膜晶体管中栅极/漏极电压依赖的接触电阻的单器件方法。考虑到接触电阻随漏极/栅极电压的变化，本工作拓展了传统的过渡电圧方法，以应对新兴器件中普遍存在的肖特基接触和电流拥挤情况。同时，该方法可以利用单个器件独立地提取源极和漏极处的接触电阻，这不仅在源极与漏极之间不对称肖特基势垒的情况中是必要的，而且对电路的精确建模至关重要。利用所提出的方法，本工作进一步研究了接触电阻与沟道缩放以及偏置电压之间的依赖关系。除了碳纳米管薄膜晶体管，本工作还在金属氧化物薄膜晶体管以及先进的硅基场效应晶体管中验证了该方法对提取新兴晶体管接触电阻的通用性。相比于已报道的方法，本文提出的方法避免了复杂的迭代、人为引入参数以及沟道缩放条件，能够进一步提高对各种新兴晶体管中复杂金属/半导体接触特性的普适理解。
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.
文章链接：
