Novel techniques to fabricate suspended CVD-graphene devices for sensing applications

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Ever since its rediscovery in 2004, graphene has drawn vast attentions in many fields of science due to its remarkable properties such as high carrier mobility, high elasticity, transparency, electromechanical modulation and many more. Furthermore, it has been claimed that graphene would substitute present semiconductors technologies owing to its fascinating properties. Numerous theoretical and empirical studies on graphene have been produced over the last decade and many graphene-based applications have been proposed and fabricated. Most of those applications used supported graphene while few of them employed suspended graphene. However, it has been widely reported that the intrinsic properties of graphene can be hindered by the supporting materials. Therefore, suspended graphene acquires much more significance in research and is highly desired to utilise in many applications. In this study, we have presented novel techniques in obtaining a high yield of CVD graphene membranes suspended over different shapes of cavities (holes) and pillars/posts. The innovative technique used to transfer graphene in this work is a dry technique and can be used not only to transfer graphene on cavities/pillars but also to transfer large graphene sheets to cover a whole wafer. Also, the cleaning method developed in this work to clean suspended graphene membranes is unprecedented and can also be adopted for use in cleaning processes in mass production lines. In addition, sensing applications have been presented in this work, such as gas sensors and pressure sensors, to demonstrate the feasibility of our devices. The fabrication of devices in this work is a photolithography process which intrinsically has a great importance due to cost efficiency and compatibility with the current infrastructure of micro/nanoelectronics industry. Additionally, the techniques presented in this work are optimizable and can be employed to fabricate graphene-based electronic devices in a large scale of production.