无序化石墨烯反点格中电子输运与能隙调控研究

Graphene antidot lattices, produced by regular perforation in graphene, can create a considerable bandgap by establishing a periodic potential modulation in graphene, which can overcome the drawback of the absence of a bandgap in pristine graphene, and have promising applications. However, the unavoidable disorder in realistic materials may destroy the established bandgap and deteriorate the mobility by altering the electronic transport properties, especially, by inducing localization of electrons. It is urgent to determine the effects of various kinds of disorder and find the way of keeping a high mobility and a controllable bandgap simultaneously. In this project, we propose to use the efficient linear-scaling quantum transport simulation method implemented on graphics processing units to study the electronic transport properties in graphene andidot lattices, with an emphasis on considering the unique correlated geometrical disorder in graphene antidot lattices, and comparing with conventional disorders. By calculating the important physical quantities such as electronic density of states, electrical conductivity, and localization length, we analyze the mechanisms of electron localization in various kinds of disorder with varying strength, and seek an effective way of controlling the bandgap and the transport in disordered graphene antidote lattices. The obtained results will provide theoretical guidance for the development of novel nanoelectronic devices based on graphene antidote lattices, and will be helpful for the progress in developing and applying large-scale quantum transport simulation methods.

在石墨烯中规则地进行穿孔所得到的石墨烯反点格结构通过在石墨烯中建立周期性的势能调制可产生一个可观的能隙，能克服原有石墨烯没有能隙的缺陷，应用前景重大。然而，实际材料中不可避免的无序可通过对电子输运性质的改变特别是产生电子的局域化来破坏已建立的能隙并降低迁移率。如何确定各种无序所产生的影响以及找到同时保持高迁移率和可控能隙的方案是亟待解决的问题。本项目拟运用在图形处理器中实现的高效线性标度量子输运模拟方法对石墨烯反点格中的电子输运性质进行系统的研究，重点考察石墨烯反点结构中特有的关联的几何无序，并与普通非关联无序对比。通过计算电子态密度、电导率、局域化长度等重要物理量，分析在不同无序种类和强度作用下电子局域化的物理机制，寻求无序化结构下石墨烯反点格中能隙调制和输运调控的有效方案。研究结果将为基于石墨烯反点格的新型纳米电子器件的开发提供理论指导，并有助于推动大尺度体系量子输运模拟方法的发展。

在石墨烯中规则地进行穿孔所得到的石墨烯反点格结构通过在石墨烯中建立周期性的势能调制可产生一个可观的能隙，能克服原有石墨烯没有能隙的缺陷，应用前景重大。然而，实际材料 中不可避免的无序可通过对电子输运性质的改变特别是产生电子的局域化来破坏已建立的能隙并降低迁移率。如何确定各种无序所产生的影响以及找到同时保持高迁移率和可控能隙的方案是亟待解决的问题。本项目拟运用在图形处理器中实现的高效线性标度量子输运模拟方法对石墨烯反点格中的电子输运性质进行系统的研究，重点考察石墨烯反点结构中特有的关联的几何无序，并与普通非关联无序对比。通过计算电子态密度、电导率、局域化长度等重要物理量，分析在不同无序种类和强度作用下电子局域化的物理机制，寻求无序化结构下石墨烯反点格中能隙调制和输运调控的有效方案。研究结果将为基于石墨烯反点格的新型纳米电子器件的开发提供理论指导，并有助于推动大尺度体系量子输运模拟方法的发展。..我们运用自主开发的线性标度量子输运程序系统研究了石墨烯反点格中存在几何无序时的电子结构和输运性质。完美的石墨烯反点格具有一定大小的带隙，表现为半导体。我们发现，几何无序会破坏带隙，但同时会通过安德森局域化导致一个输运能隙。定量地，我们发现该输运能隙正比于反点的平均半径、并反比于反点之间平均距离的平方。反点位置的无序相对于反点半径的无序对输运的影响更为强烈。我们系统计算了不同反点尺寸下的载流子迁移率。将计算数据进行合理外推，得到了和相关实验吻合较好的结果。我们还发现，有限温度导致的无序相对于衬底提供的电荷无序较为微弱。我们的结果说明，通过控制反点格的几何尺寸能够有效地调节输运能隙和迁移率。