Influence of structural properties on ballistic transport in nanoscale epitaxial graphene cross junctions
Influence of structural properties on ballistic transport in nanoscale epitaxial graphene cross junctions
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DOI：
10.1088/0957-4484/23/39/395203
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发表时间：
2012-10-05
期刊：
影响因子：
3.5
通讯作者：
Seyller, Thomas
中科院分区：
文献类型：
--
作者：
Bock, Claudia;Weingart, Sonja;Seyller, Thomas
本文研究了外延单层石墨烯和外延准自由单层石墨烯中材料和器件特性对弹道输运的影响。我们的研究包括：（a）二维（2D）霍尔条中的磁输运，（B）非对准和阶梯边缘对准正交交叉结的温度和磁场依赖的弯曲电阻，以及（c）交叉结的引线宽度对弹道输运的影响。我们发现，弹道传输是高度敏感的散射在碳化硅衬底的步骤边缘。如果交叉结的引线宽度从50 nm减小到30 nm，则观察到弹道输运的抑制。在一个50 nm宽的设备上制备的准独立的石墨烯，我们观察到一个渐进的过渡从弹道到扩散传输制度，如果温度从4.2增加到约50 K，虽然二维霍尔酒吧显示温度无关的迁移率。因此，在1D器件中，附加的温度依赖性散射机制起着关键作用。
In this paper we investigate the influence of material and device properties on the ballistic transport in epitaxial monolayer graphene and epitaxial quasi-free-standing monolayer graphene. Our studies comprise (a) magneto-transport in two-dimensional (2D) Hall bars, (b) temperature- and magnetic-field-dependent bend resistance of unaligned and step-edge-aligned orthogonal cross junctions, and (c) the influence of the lead width of the cross junctions on ballistic transport. We found that ballistic transport is highly sensitive to scattering at the step edges of the silicon carbide substrate. A suppression of the ballistic transport is observed if the lead width of the cross junction is reduced from 50 nm to 30 nm. In a 50 nm wide device prepared on quasi-free-standing graphene we observe a gradual transition from the ballistic into the diffusive transport regime if the temperature is increased from 4.2 to about 50 K, although 2D Hall bars show a temperature-independent mobility. Thus, in 1D devices additional temperature-dependent scattering mechanisms play a pivotal role.