等离子体辅助调制二维过渡金属硫族化合物的相结构及其物性研究

In recent years, the research field of transition metal dichalcogenides (TMC) develops rapidly, and there are many gaps to be filled in the phase control. The performance of TMC depends on its phase structure to a large extent. Modulation of phase transitions between different phases on a two-dimensional scale is of great significance for the phase control and electronic properties of materials. In this project, TMC (including MoX2, TiSe2 and NbSe2, etc.) were prepared by three methods: mechanical exfoliation, chemical vapor deposition, physical vapor deposition combined with chemical vapor deposition. Plasma of different gases can be used to inject electrons into TMC, heteroatom doping, vacancy and/or stress induced by physical collision, etc., which can help trigger the phase transition of TMC. The phase control of plasma-induced TMC and the physical properties of each phase TMC were investigated. We can know the TMC phase transition strategy triggered by plasma of different gases and phase library can be extended. A kind of post-phase modulation method, which can be used for single-layer to multi-layer, large-scale, simple operation and wide application range without metal element doping, can be developed.In addition, two-dimensional TMC materials and flexible devices with excellent physical properties were prepared by large-size TMC film combined with plasma technology to realize large-scale phase transition.

近年过渡金属硫族化合物（TMC）的研究领域急速发展，而对其相变的控制仍存在诸多空白。TMC的性能在很大程度上取决于其相结构，在二维尺度上调制不同相之间的相变对于调控材料的多型性和电子性能有着重要意义。本项目中用三种方法制备TMC（包括MoX2、TiSe2和NbSe2等）：机械剥离、化学气相沉积法、物理气相沉积结合化学气相沉积的方式。利用不同气体的等离子体可以实现在TMC中注入电子、引起杂原子掺杂、形成空位和/或物理碰撞引入的应力等，有助于触发TMC的相变。着重研究等离子体诱导TMC相变的调制和各相TMC的物理性能。掌握不同气体的等离子体触发不同种类的TMC结构相变的策略，丰富相结构库。探索出一种可用于单层至多层、规模化、操作简便且无金属元素掺杂的适用范围非常广的相变调制方法。此外，利用TMC大尺寸薄膜结合等离子体技术，实现规模化相变，制备出物性优异的TMC二维材料和柔性器件。

二维TMCs由于其独特的结构和丰富的物理化学性质，在光电子、电子、能源和催化等领域具有广阔的应用前景。然而，二元TMCs的稳定性、带隙调谐性等方面存在一定的局限，从而导致其应用受到限制。本项目主要研究内容包括：（1）研究二维过渡金属硫化合物在高温等极端环境中的行为对于器件加工和高温应用的影响。通过实时原位和非原位的形态和光谱观测，研究了不同气氛下MoS2的物理性质的演变。这些研究将有利于开展二维TMCs在恶劣条件下的功能应用。（2）可控制备二维TMCs三元合金，调控合金比例，实现对材料的带隙和电学调控。已实现Mo1-xWxS2、Mo1-xWxSe2和MoS2xSe2(1-x)晶圆级薄膜的制备，带隙可调宽度达到1.56~2.0 eV，此方法也可拓展到更多三元合金的可控制备。（3）调制化学气相沉积法的生长环境实现对二维TMCs的形貌及其物性调控。在多种衬底上制备了多种具有代表性的TMCs，研究不同氧化条件下的生长规律，证明了TMCs颗粒或薄膜生长的普遍规律，提供了通过设计的氧化条件生长和调制不同氧掺杂浓度的特定TMCs材料。（4）实现具有可控硫化、硒化和碲化的二维TMCs的制备，发现生长的二维TMCs的稳定性与其初始元素比密切相关，化学计量键合的TMCs具有优异的稳定性。为大面积垂直异质结的直接叠层制备提供了可行性。因此，本项目的实施为TMCs材料的未来应用奠定了重要基础。