Naval Research Laboratory, Washington, DC, USA.
George Mason University, Fairfax, VA, USA.
Sci Rep. 2017 Feb 9;7:41713. doi: 10.1038/srep41713.
Since its discovery, graphene has held great promise as a two-dimensional (2D) metal with massless carriers and, thus, extremely high-mobility that is due to the character of the band structure that results in the so-called Dirac cone for the ideal, perfectly ordered crystal structure. This promise has led to only limited electronic device applications due to the lack of an energy gap which prevents the formation of conventional device geometries. Thus, several schemes for inducing a semiconductor band gap in graphene have been explored. These methods do result in samples whose resistivity increases with decreasing temperature, similar to the temperature dependence of a semiconductor. However, this temperature dependence can also be caused by highly diffusive transport that, in highly disordered materials, is caused by Anderson-Mott localization and which is not desirable for conventional device applications. In this letter, we demonstrate that in the diffusive case, the conventional description of the insulating state is inadequate and demonstrate a method for determining whether such transport behavior is due to a conventional semiconductor band gap.
自发现以来,石墨烯作为一种具有无质量载流子的二维(2D)金属,具有极高的迁移率,这归因于能带结构的特性,导致理想的完美有序晶体结构出现所谓的狄拉克锥。由于缺乏能隙,无法形成传统器件的几何形状,这一特性使得石墨烯在电子器件中的应用受到限制。因此,已经探索了几种在石墨烯中诱导半导体能隙的方案。这些方法确实导致了样品的电阻率随温度降低而增加,类似于半导体的温度依赖性。然而,这种温度依赖性也可能是由高度扩散的输运引起的,在高度无序的材料中,这种输运是由安德森-莫特局域化引起的,这对于传统的器件应用是不理想的。在这封信中,我们证明了在扩散的情况下,传统的绝缘状态描述是不充分的,并演示了一种方法来确定这种输运行为是否是由于传统的半导体能隙。