新型二维晶体材料锑烯的电子能带结构及输运特性研究

Very recently, arsenene and antimonene consisting of atomically thin layer of group V elements have attracted tremendous interests as new members of elemental two-dimensional crystals. First principle calculations predict that arsenene and antimonene are thermodynamically stable and they undergo semimetal to semiconductor transitions dependant on the number of atomic layers. It has also been predicted that biaxial tensile strain can turn the indirect band gap of arsenene and antimonene into direct band gap. However, no experimental results have been reported about arsenene or antimonene and the mechanisms of predicted band structure transitions are still unknown. In this proposal, the applicants and colleagues plan to apply mechanical exfoliation and liquid phase exfoliation method to produce few-layer or even monolayer antimonene out of metallic antimony. We plan to study the evolvement of electronic band structure on varying number of layers, external field and external strain. We hope to clarify the mechanisms of thickness dependant semimetal to semiconductor transition in antimonene. We will design and fabricate thin film transistors based on antimonene and study the transport properties with varying number of atomic layers, external field and temperatures. Through this project, we hope to provide experimental evidence to test the theoretical predictions on band structure transitions in antimonene and unravel the unknown mechanisms. Our work might pave the road to future applications of microelectronic and optoelectronic devices based on two-dimensional antimonene.

最近，砷烯、锑烯材料作为由第五主族原子构成的新型二维晶体单质材料受到了极大关注。第一性原理计算预言砷烯、锑烯具有热动力学稳定性，存在层数依赖的半金属——半导体转变，以及外加应变条件下的间接带隙到直接带隙转变。然而，与砷烯锑烯相关的实验工作尚未有报道。本项目拟采用机械剥离法和液相剥离法以块体金属锑为原料制备少层或者单层的二维锑烯材料。研究其电子能带结构随着原子层数以及外加电场所发生变化的调制规律，研究在外加应变条件下电子能带结构的转变，揭示少层乃至单层锑烯材料中半金属到半导体转变的物理机制；设计制备基于二维锑烯材料的薄膜晶体管器件，研究其输运特性随着原子层数、外加电场、温度等条件发生变化的调制规律。通过本项目的研究，期望能从实验上对前期理论计算的结果加以验证，揭示其中的物理机制，为进一步设计制备基于二维砷烯和锑烯材料的微电子和光电子器件打下坚实的基础。

锑烯是由第五主族元素锑构成的新型二维晶体材料。理论预测锑烯具有层数依赖的半金属到半导体转变，且稳定性优于黑磷烯，然而实验工作的进展滞后，其主要原因是缺乏制备高质量锑烯的实验手段。本研究围绕新型二维晶体材料锑烯的实验制备，锑烯材料的形貌及原子结构表征，锑烯的电子结构、光学、电学性质以及相关的应用展开。我们开发了基于范德华外延法生长单晶锑烯薄膜的技术，生长的锑烯薄膜晶体质量好，稳定性高，可以方便地转移到其他衬底上。少层锑烯薄膜具有良好的导电性，良好的柔性以及在可见光波段优秀的透过率，从而在透明柔性导电薄膜领域具有潜在的应用前景。我们发明了一种基于液相剥离方法制备锑烯纳米片的技术，该方法能够实现锑烯纳米片大产率的制备，晶体质量也比较高。这既为后续二维锑烯材料的实验研究工作奠定了基础，同时该方法也有可能应用于未来锑烯材料的工业化生产。我们还进一步研究了二维锑烯材料的衍生物锑烯量子点，发展了基于液相剥离法制备锑烯量子点的技术，得到了高质量的锑烯量子点样品。在此基础上，我们研究了锑烯量子点的非线性光学特性，发现锑烯量子点具有优异的饱和吸收特性，并搭建了基于锑烯量子点的调Q光纤激光器；发现锑烯量子点的空间自相位调制相应，并设计了基于该效应的全光开关，展示了锑烯量子点作为一种新型的非线性光学材料所具有的应用前景。