单层石墨烯中的准粒子是无质量的狄拉克费米子，具有类光的能量色散关系。在连续的单层石墨烯中引入高质量的纳米尺寸的p-n结，不仅对准粒子基本物理性质的研究(比如Klein隧穿效应)具有非常重要的意义，同时也是石墨烯基量子电子光学器件的发展的重要基础。本文通过局域的改变单层石墨烯与Cu衬底的距离，在石墨烯中引入了纳米尺寸的，边界原子级转变的准一维和零维n-p-n结。并通过扫描隧道显微镜(STM)对制备得到的准一维和零维n-p-n结中无质量狄拉克费米子的受限情况进行了系统研究。 本文主要结论如下： (1)：在接近铜熔点的高温下生长石墨烯时，铜衬底表面会发生大量的重构，生成大量的一维台阶，表面单原子空位岛以及吸附原子平台等结构。 (2)：通过实验验证了，当改变石墨烯与金属衬底的距离时，确实可以单调的改变石墨烯狄拉克点的位置，可以在石墨烯中引入边界原子级转变的p-n结结构。 (3)：通过Cu衬底台阶的调控作用，在连续的石墨烯中形成了准一维的n-p-n结；并且通过低温下的STM测量，我们直接得到了受限粒子的准束缚态以及波函数的分布情况。该文章首次从原子尺度研究了一维n-p-n结势垒对连续石墨烯中的无质量的狄拉克费米子的限制作用。 (4)：通过铜衬底上单层空位岛结构，在石墨烯中引入了纳米尺寸，边界转变原子级陡峭的零维石墨烯n-p-n结。通过扫描隧道显微镜，我们得到了不同尺寸以及不同形状量子点中的准粒子的束缚态(STS)，以及这些准束缚态在量子点内部的空间分布情况(STS mapping)。接着，我们又从类光学的角度，分析了不同量子点的形状与尺寸对准束缚态及其量子干涉现象的影响。我们的研究从原子尺度上证明了单层石墨烯中无质量的狄拉克费米子的电子光学效应。

Charge Carries in graphene are massless Dirac fermions, and exhibit light-like energy dispersion relation. Creation of high-quality p-n junctions in graphene monolayer is vital, not only in studying the fundamental science of massless Dirac fermions, for example the Klein tunneling, but also because they will be essential components in quantum electron optics based on graphene. Here, we realize nanoscale 1D and 0D n-p-n junctions with atomically sharp boundaries in graphene monolayer by locally changing the graphene-Cu separations. By Scanning Tunneling Microscopy and Scanning Tunneling spectra, we systematically investigate the effect of quasi-one dimensional and zero-dimensional n-p-n junctions on trapping the massless Dirac fermions. The main results are obtained as follows: (1): During the high-temperature growth process (close to the melting point of copper), massive one-dimensional copper steps and surface Cu atomic vacancies islands or adatoms’ clusters emerge through migration and massive diffusion of the surface Cu atoms. (2): Our experiment demonstrate that the Dirac point can be changed by locally changing graphene-Cu separations for graphene on Cu foils. Nanoscale n-p junctions with atomically sharp boundaries in graphene monolayer can be created by locally changing the graphene-Cu separations near the step edge of Cu substrate and the boundary of monolayer vacancy islands of Cu substrates. (3): Quasi-1D n-p-n junctions in a continuous graphene monolayer are generated along the steep part near a Cooper step edge. Via STM measurements, we directly probe the quasi-bound states and image the wave functions of the confined massless Dirac fermions within the 1D n-p-n junction. Our experiment investigate trapping effect of 1D n-p-n junction in atomic scale for the first time. (4): We realize nanoscale p-n junctions with atomically sharp boundaries in graphene monolayer by using monolayer vacancy island of Cu surface. By using scanning tunneling microscopy, we observe resonances of quasi-bound states in the GQDs with various sizes and directly visualize effects of geometries of the GQDs on the quantum interference patterns of the quasi-bound states. Following, we analyzed the above results by analogizing the GQDs with optical systems. Our results can be treated as an atomic-scale verification of the quantum electron optics based on graphene.