单层/少层二碲化钼（MoTe2）纳米片晶体管器件中的界面调控研究

Mono-layered/few-layered transition metal dichalcogenides (TMDs) nanosheets are ideal channel materials for the silicon beyond nanoelectronics. However, the carrier mobility for such TMDs nanosheets-based devices is generally seriously limited to be below the theoretical value. To solve this problem, it is crucial to engineer the interface between high-k dielectrics and semiconducting TMDs nanosheets, and clarify the mechanism of carrier scattering sources on the mobility. This project focuses on the interface control between high-k dielectrics and mono-layered /few-layered Molybdenum telluride (MoTe2) nanosheets, which show good potential as channel materials for the future silicon beyond nanoelectronics. We will investigate the deposition process of high-k dielectrics onto the surface of MoTe2 nanosheets, aiming to promote the conformal growth thus the control of interfacial quality. Meanwhile, we proposed to construct high-k dielectrics/passivation layer/ MoTe2 nanosheets gate stacks, by inserting an ultrathin interfacial passivation layer via a co-sputtering followed by post-thermal treatment method, to improve the interfacial quality with low density of interface traps. This study will provide an insight into the mechanism of carrier scattering sources on the mobility, facilitating the fabrication of high performance mono-layered/few-layered MoTe2 nanosheets-based devices.

单层/少层过渡金属硫化物(TMDs)纳米片是后摩尔定律时代理想的非硅基纳电子器件沟道材料，但是普遍存在载流子迁移率偏低的难题。解决这一科学问题的关键在于调控栅介质/TMDs纳米片界面，阐明散射机制对载流子迁移率的影响。本项目以具有极大非硅基纳电子器件应用潜力的较新颖单层/少层二碲化钼（MoTe2）纳米片为研究对象，拟研究直接构建栅介质/MoTe2纳米片堆栈结构，通过优化栅介质沉积工艺，促进栅介质/ MoTe2的共形生长，调控栅介质/MoTe2界面。此外，提出利用多靶磁控共溅射制备极薄钝化层后进行热处理的界面调控新思路，构建栅介质/界面钝化层/MoTe2纳米片堆栈结构，降低界面电荷陷阱密度，提高载流子迁移率。本课题的实施将为阐明单层/少层MoTe2纳米片晶体管器件中载流子散射机制对迁移率的影响，制备高性能单层/少层MoTe2纳米片基纳电子器件提供理论与实验依据。

新型单层/少层TMDs薄膜（如MoTe2、WTe2等）是后摩尔定律时代理想的非硅基纳电子器件沟道材料。针对MoTe2薄膜容易发生结构性相变、表面化学不稳定及掺杂改性等特点，本项目围绕大面积、高质量、晶相可控的少层MoTe2薄膜化学气相合成、氧化动力学及量子输运特性、掺杂改性等开展了系统研究。通过本项目的实施，我们（1）成功合成了四种均匀的分别以半金属性1T′相为主的混合相、半导性100% 2H相、以半导性2H相为主的混合相以及100%半金属性1T′-MoTe2薄膜，系统研究了合成过程中通过碲化速率调控MoTe2薄膜的半金属相-半导相-半金属相的相变演化过程，并对相应演变机理进行了分析和解释，探究了生长条件与薄膜相变、厚度、结构、组分、结晶情况以及电学性质关系；（2）系统研究了MoTe2薄膜的氧化动力学及量子输运特性，证实MoTe2薄膜具有非平衡性氧化特性，氧化生成碲金属团簇反应副产物，团簇生成依赖于碲化温度、表面电负性以及结构多态性。量子输运研究表明，原始1T′-MoTe2薄膜具有明显半导性输运特性，表面氧化层显著影响MoTe2薄膜的输运特性；（3）系统研究了Ta掺杂对于半导性2H-MoTe2单晶纳米片物理性质影响，表明通过非磁性元素掺杂控制纳米片结构性缺陷、结合厚度减薄后纳米片具有的边缘态会给予MoTe2纳米片室温铁磁特性。此外，本项目还拓展研究了MoTe2薄膜半金属性-半导性面内异质结构筑、半金属性MoTe2薄膜电化学析氢特性、半金属性WTe2薄膜的可控制备及室温稳定性等。本项目执行期间，共发表期刊论文11篇，会议论文1篇，培养研究生2名。