Electrical and Computer Engineering, Michigan State University, East Lansing, MI 48824, USA.
Nanotechnology. 2012 Mar 16;23(10):105501. doi: 10.1088/0957-4484/23/10/105501. Epub 2012 Feb 21.
With their sub-nanometer inter-sheet spacing, few-layer graphenes (FLGs) are alignment-free building blocks for nanosensors based on the inter-sheet effects. In this paper, we have tackled the challenges towards batch fabrication of inter-sheet graphene sensors through controlled layer engineering, edge tailoring and selective electrode fabrication on different atomic layers. An oxygen plasma etching (OPE) technique is developed to remove graphene layer by layer, enabling the batch fabrication of FLGs in a controllable fashion because of the faster speed and readiness of patterning of this process as compared to the conventional mechanical exfoliation. Vapor sensing experiments have shown that 'inter-sheet' sensors possess a higher sensitivity than conventional 'intra-sheet' ones. Vapor sensitivity is improved more than two times in normalized resistance changes by taking the 'inter-sheet' design upon exposure to 0.5% ethanol-nitrogen mixture and 500 Pa water vapor environments, respectively. These remarkable improvements can mainly be attributed to the inter-sheet effects such as electron tunneling, chemical doping, physical insertion and enhanced edge effects. Such effects may result from molecule adsorption/desorption, force/displacement, pressure, surface tension or thermal energy, and can potentially remarkably enrich the applicable transduction mechanisms.
具有亚纳米层间间距的少层石墨烯（FLG）是基于层间效应的纳米传感器的无对准构建块。在本文中，我们通过控制层工程、边缘修饰和在不同原子层上选择性电极制造来解决了批量制造层间石墨烯传感器的挑战。开发了一种氧等离子体刻蚀（OPE）技术，可逐层去除石墨烯，由于该工艺的速度更快且易于图案化，因此与传统的机械剥落相比，可以以可控的方式批量制造 FLG。蒸气传感实验表明，“层间”传感器比传统的“层内”传感器具有更高的灵敏度。通过在暴露于 0.5%乙醇-氮气混合物和 500 Pa 水蒸气环境时采用“层间”设计，归一化电阻变化的蒸气灵敏度分别提高了两倍以上。这些显著的改进主要归因于电子隧穿、化学掺杂、物理插入和增强的边缘效应等层间效应。这些效应可能源于分子吸附/解吸、力/位移、压力、表面张力或热能，并且可能显著丰富适用的转换机制。
