基于负电容效应的超低功耗MoS2/HfO2超晶格异质结场效应晶体管研究

With the development of integrated circuit (IC) technology into the era of nanoscale, the problem of "power dissipation restriction" is increasingly prominent. Exploring new-style ultra-low power nanoscale field effect transistor plays an important role in promoting the sustainable development of the nano-IC technology. This project plans to build the "monolayer-MoS2/HfO2" superlattice heterojunction field effect transistor (HFET) by introducing ultra-thin HfO2, which have negative capacitance effect, into the transistor gate insulating layer and the "monolayer-MoS2/HfO2" superlattice channel. The dependence relationships between HFET performance and the properties of monolayer-MoS2 and ultra-thin HfO2 will be analyzed by adjusting the experimental process and employing the first principles calculation and TCAD simulation. The variation laws of the threshold voltage and the mobility will be summarized under different process parameters. The dynamic mechanism of negative capacitance effect of the ultra-thin HfO2 will be explored from microscopic angle. The coupling relationships of electron-electron among the MoS2 layers and the bound charge-bound charge among the HfO2 layers will be confirmed. At last, the ultra-low power consumption "monolayer-MoS2/HfO2" superlattice HFET will be obtained through optimizing technology conditions in this project. The research of this project is hopeful to solve the basic scientific problems of ultra-low power consumption superlattice HFET and it should provide certain technical reference for researching and developing ultra-low power field effect transistor.

在集成电路（IC）技术进入纳米尺度的时代，“功耗限制”问题日益突出，探索新型超低功耗纳米场效应晶体管对推动纳米IC技术的可持续发展具有重要作用。本项目将具有负电容效应的超薄HfO2引入到晶体管栅绝缘层和“单层MoS2/HfO2”超晶格沟道中，构建“单层MoS2/HfO2”超晶格异质结场效应晶体管（HFET）。通过调控实验工艺，在第一性原理计算和TCAD的辅助下，分析单层MoS2和超薄HfO2的物性与HFET性能之间的依赖关系，总结HFET的阈值电压和迁移率随工艺参数的变化规律。从微观角度探索超晶格异质界面附近超薄HfO2负电容效应的动力学机制，明确超晶格内MoS2层间电子-电子和HfO2层间束缚电荷-束缚电荷的耦合关系。通过条件优化，最终制得超低功耗“单层MoS2/HfO2”超晶格HFET。本项目的研究有望解决超低功耗负电容HFET的基本科学问题，为超低功耗晶体管的研发提供一定的技术参考。

在集成电路技术进入纳米尺度的时代，“功耗限制”问题日益突出，探索新型超低功耗纳米场效应晶体管对推动纳米集成电路技术的可持续发展具有重要作用。本项目将单层MoS2与超薄HfO2结合，以HfO2为绝缘层，以单层MoS2/HfO2超晶格异质结为沟道，构建场效应晶体管，借助HfO2薄层的负电容效应逐层减小栅极电压，降低器件功耗。本项目的主要研究内容及结果有：（1）采用PLD和CVD等技术成功制备了高质量的MoS2、HfO2薄膜及MoS2/HfO2异质结，优化了工艺参数；（2）提出了一种二维材料转移新方法，可以广泛应用于二维材料转移及范德瓦尔斯异质结的制备；（3）基于MoS2薄膜，构建了隧穿热电子转移放大器，其发射极电流为10 mA，共发射极电流增益为0.11。（4）利用上述MoS2薄膜和异质结构，构建了场效应晶体管，总结器件的性能随工艺参数的变化规律，获得了亚阈值摆幅为55 mV/dec，阈值电压0.5 V、开关比为10^6的晶体管。（5）从微观角度探索超晶格异质界面附近超薄HfO2负电容效应的动力学机制，明确超晶格内MoS2层间电子-电子和HfO2层间束缚电荷-束缚电荷的耦合关系。本项目内容可以为研究超低功耗负电容场效应晶体管的基本科学问题，研发负电容晶体管提供技术参考。