Department of Materials Science and Engineering, University of Pennsylvania, Philadelphia, Pennsylvania 19104, United States.
ACS Nano. 2011 May 24;5(5):3475-82. doi: 10.1021/nn102322s. Epub 2011 Apr 7.
Graphene is an interesting electronic material. However, flat monolayer graphene does not have significant gap in the electronic density of states, required for a large on-off ratio in logic applications. We propose here a novel device architecture, composed of self-folded carbon nanotube-graphene hybrids, which have been recently observed experimentally in Joule-heated graphene. These experiments demonstrated the feasibility of cutting, folding, and welding few-layer graphene in situ to form all-carbon nanostructures with complex topologies. The electronic gap of self-folded nanotubes can be combined with the semimetallicity of graphene electrodes to form a "metal-semiconductor-metal" junction. By ab initio calculations we demonstrate large energy gaps in the transmission spectra of such junctions, which preserve the intrinsic transport characteristics of the semiconducting nanotubes despite topologically necessary disinclinations at the flat graphene-curved nanotube interface. These all-carbon devices are proposed to be constructed by contact probe cutting and high-temperature annealing and, if produced, would be chemically stable at room temperature under normal gas environments.
石墨烯是一种有趣的电子材料。然而，对于逻辑应用中所需的大开-关比，平面单层石墨烯在电子态密度方面没有显著的间隙。在这里，我们提出了一种新的器件结构，由自折叠碳纳米管-石墨烯杂化结构组成，最近在焦耳加热石墨烯的实验中观察到了这种结构。这些实验证明了在原位切割、折叠和焊接少层石墨烯以形成具有复杂拓扑结构的全碳纳米结构的可行性。自折叠纳米管的能隙可以与石墨烯电极的半金属性相结合，形成“金属-半导体-金属”结。通过从头算计算，我们证明了这种结的传输谱中存在大的能隙，尽管在平坦的石墨烯-弯曲纳米管界面处存在拓扑上必需的不连续性，但保留了半导体纳米管的固有传输特性。这些全碳器件拟通过接触探针切割和高温退火来构建，如果制备成功，在室温下正常气体环境中具有化学稳定性。
