双层石墨烯/六方氮化硼异质结的插层生长及其性能研究

Graphene/hexagonal boron nitride (G/h-BN) heterojunction has become a research focus in two-dimensional material heterojunction on the strength of its high carrier mobility and adjustable electronic energy band. So far problems still exist in the preparation of G/h-BN heterojunctions, , such as the tendency of taking in some defects, slow growth and unable to control the number of graphene layers. The previous studies by the applicant demonstrated that when graphene was prepared by chemical vapor deposition, and if the growth conditions on both sides of copper foil could be controlled, the activated carbon atoms and graphene edge carbon atoms could migrate between the two sides of copper foil. In view of this, this project intends to realize the intercalation growth of graphene between hexagonal boron nitride and copper foil by means of chemical vapor deposition on the copper foil substrate. The graphene layer is in intercalated growth, the carbon atoms are catalyzed from copper foil and carbon atom migration is controllable, which are conducive to the preparation of G/h-BN heterojunction with high interface quality, fast growth rate and controllable number of graphene layers. Thus, we can achieve our final purpose in this way: the carbon atom migration would be regulated to prepare the bilayer graphene/boron nitride vertical heterojunction, and the external vertical electric field would be applied to regulate the semiconductor properties. Based on the experimental data, a theoretical model would be established to clarify the energy band structure of the bilayer graphene/hexagonal boron nitride heterojunction, the morel superlattice, fractional quantum hall effect and other characteristics of the theoretical mechanism, providing theoretical guidance for the preparation of multifunctional two-dimensional heterojunction devices.

石墨烯/六方氮化硼（G/h-BN）异质结凭借载流子迁移率高，电子能带可调整等优点成为二维材料异质结中的研究热点。目前G/h-BN异质结制备存在着容易引入缺陷、生长缓慢、石墨烯层数无法调控等问题。申请人前期研究表明，利用化学气相沉积法制备石墨烯时，调控铜箔两面生长条件，可使活性碳原子以及石墨烯边缘碳原子在铜箔两面间迁移。鉴于此，本项目拟通过化学气相沉积法在铜箔基底上，实现石墨烯在六方氮化硼与铜箔之间插层生长。由于石墨烯层是插层生长、碳原子源于铜箔催化和碳原子迁移量可控，有利于制备界面质量高、生长速度快、石墨烯层数可控的G/h-BN异质结。最终通过调控碳原子迁移量，制备双层石墨烯/六方氮化硼垂直异质结，并实现外加垂直电场对其半导体特性的调控。结合实验数据建立理论模型阐明双层石墨烯/六方氮化硼异质结的能带结构，莫尔超晶格，分数量子霍尔效应等特性理论机制，为制备多功能二维异质结器件提供理论指导。

二维异质结光电性能的调控一直是近年来理论计算领域的热点之一。本项目从理论上分别对PtS2/MoTe2, GaN/WSe2, GaN/BS, SiC2/BP5等二维异质结的光电特性开展了较为全面的研究工作。计算了不同体系异质结的原子结构、电子结构，系统研究了外加电场、外加应力等调控方式对体系的电子结构，光吸收特性等性质的影响。获得的了许多研究成果，例如在应力和外加电场调控下GaN/WSe2异质结能带结构会从半导体转变为金属特性。这些研究为制备可进行外电场和应力调控的二维光电探测器的制备提供了理论支持。同时我们也系统研究了Ti, N，Ti-N掺杂对石墨烯吸附SO2等有害气体的效果的影响, 为石墨烯在有害气体吸附领域的得应用前景提供了理论支撑。此外我们还研究了Cd/SiI2和GaN/BS异质结光催化水分解特性。随着研究的深入，我还系统研究了空位，掺杂，元素对称性、吸附对WSe2光生电流效应的影响，为制备自供电、低能耗、高偏振灵敏的光电探测器提供了理论基础。项目开展期间在国际学术期刊发表研究论文13篇，基本圆满完成工作任务，后续研究仍在积极进行中。