全二维材料场效应晶体管器件研究

Due to the natural immunity to short channel effects, two-dimensional (2D) materials represent the ultimate scaling in the vertical direction and therefore is expected to advance Moore’s Law in future. Considering characteristics of different 2D materials, we design a field-effect transistor device with MoS2 as a conductive channel, graphene as electrodes, and hBN as dielectrics. This device structure totally formed by 2D materials could exhibit the advantages of component parts: high on/off ratio of the semiconductor MoS2, high current-carrying capacity of the semimetal graphene, and excellent dielectric properties of the insulator hBN. Meanwhile, it could solve the problems of depositing dielectrics in traditional transistors and the problems of effectively switching off when graphene is utilized as conductive channel. Furthermore, using graphene as electrical contacts, the contact resistance is likely to be reduced with appropriate processing, even to realize ohmic contact. In this study, with the research on the scientific problems of the scattering mechanisms of MoS2 and the carrier transportation mechanisms between graphene and MoS2, theoretical supports are provided for the technical methods to improve carrier mobility and to reduce contact resistance. We will further fabricate high-performance field effect transistor device based on hybrid all-2D materials, and advance the development of electronics on 2D materials.

二维材料具有对短沟道效应的天然免疫力，是按比例缩小器件尺寸以提高器件性能的终极目标，因而被寄予延续摩尔定律的厚望。本研究综合考虑了不同二维材料的特点，提出了以MoS2为导电沟道，以石墨烯为接触电极，和以hBN为绝缘栅介质的全部由二维材料组成的场效应晶体管器件结构。该器件结构能够充分发挥半导体MoS2的大开关比、半金属石墨烯的高载流能力、和绝缘体hBN的卓越介电性能的优势，又可以解决传统二维晶体管器件中栅介质难以制备以及采用石墨烯作为导电沟道时器件不能有效关断的问题，而利用石墨烯作为二维材料的接触电极，经适当调节可减小接触电阻，甚至有望实现欧姆接触。本研究将通过对MoS2的散射机制和石墨烯/MoS2间载流子输运机理这两个科学问题的研究，为提高MoS2的载流子迁移率和减小接触电阻的工艺技术方法提供理论支持，并在此基础上实现高性能的全二维材料场效应晶体管器件制备，推进二维材料电子器件的发展。

二维材料具有对短沟道效应的天然免疫力，是按比例缩小器件尺寸以提高器件性能的终极目标，本研究针对二维二硫化钼FET器件的制备，对于二维二硫化钼材料的制备和表征，二硫化钼表面高性能栅介质的沉积以及二维材料与金属间的接触等科学技术问题展开研究，最终成功制备了以MoS2为导电沟道，石墨烯为接触电极的全二维材料组成的场效应晶体管器件。该器件有效改善了沟道材料与电极间的接触性能，与常规器件相比，将电流开关比提高了两个量级。为未来二维材料晶体管器件的接触制备提供方向。