化学气相沉积法生长的单层石墨烯具有卓越的力学、热学和电学特性, 成为新一代纳米器件的首选材料。对石墨烯电子特性的理论研究有利于推动纳米器件的发展与应用。本文基于密度泛函理论与非平衡格林函数相结合的方法, 系统地研究了石墨烯及石墨烯/氮化硼的电子结构特性。结果表明, 在高对称K点, 带隙为零。在50~400 K范围内, 由于费米面的电声子散射作用, 单层石墨烯的迁移率随着温度增加呈现显著下降趋势。此外, 通过对不同层间距的石墨烯/氮化硼结构的能带、态密度、电子密度等特性分析, 发现随着层间距增加, 能带间隙减小, 导带与价带间的能量差减小。随着原子个数的增加, 石墨烯/氮化硼超胞结构与原胞结构的带隙开度变化规律一致, 这对石墨烯基器件的结构设计具有一定的指导意义。

针对光学倒锥窄尖的制备工艺困难的问题，通过特殊设计掩膜版，利用步进式光刻机，经过一次步进，对光刻胶进行两次连续的图案化处理，突破紫外光刻机的分辨率极限，制备出尖端接近50 nm的倒锥结构图案.再对光刻胶进行回流处理，解决其分层的问题，保证了结构侧壁的光滑度及尖端的完整性.在深硅刻蚀工艺中，通过对刻蚀中各气体组分进行调整，改善了锥形结构表面形貌，使结构的均匀性和完整性得到提升.最终得到了适用于层间耦合的尖端接近50 nm的光学倒锥.

Phonon is one of the most important elementary excitations, and is fundamental for understanding thermodynamic properties, such as heat capacity, Debye temperature, and the coefficient of thermal expansion. Furthermore, electron-phonon coupling can determine the electric conductivity and superconductivity of materials. Raman spectroscopy is the most important tool to study phonon physics, and can not only be utilized to explore the lattice structure and quality of materials but also their phonon properties, electronic band structure and electron-phonon coupling. Here, we investigate the phonon physics of two-dimensional (2D) materials and the related van der Waals heterostructures by Raman spectroscopy. First, we will introduce interlayer and intralayer phonon modes. The frequency of the interlayer phonon modes can be well reproduced by the linear chain model while their intensity can be calculated by the interlayer bond polarizability model; in addition, the splitting frequency between Davydov components in multilayer 2D materials originating from the same intralayer mode in monolayer counterpart can be well fitted by the van der Waals model. Secondly, we extend these models to 2D van der Waals heterostructures. By taking twisted multilayer graphene, MoS2/graphene and hBN/WS2 heterostructures as examples, we demonstrate how to calculate the frequency and Raman intensity of the interlayer modes by the linear chain and interlayer polarizability models, respectively, which can further give the strength of the interlayer coupling and electron-phonon coupling for layer-breathing modes in van der Waals heterostructures.