Preparation Of Graphene On An Insulating Substrate And Its Electrical Properties

Graphene is a two-dimensional crystal material with sp2 carbon atoms packed into a honeycomb. It has excellent physical properties with a wide range of applications, which has attracted intense attentions. At present, the controllable production of high quality and large area graphene layer is still a bottleneck, which hinders the development of graphene. In that, many approaches have been developed for graphene growth, but the graphene prepared by most methods need to be transferred to insulative substrates for electrical isolation towards property research and device application. Therefore, it is of great importance and still a major challenge to explore direct growth of high quality and large area graphene on insulated substrates.To address this issue, we have used CVD method to direct growth of high quality and large area graphene on diamond substrates and silicon dioxide(Si O2/Si) substrates, and the related morphology, number of layers and their electrical properties were characterized. The main contents are discussed as follows:(1) Using diamond substrate for high quality graphene grown. For optimized growth conditions, the influence of the chamber pressure, growth temperature, growth time, gas flux ratio and the content of boron doping were systematically investigated. Uniform, large area grapheme has been achieved, which was checked by Raman spectroscopy.(2) Using silicon dioxide(Si O2/Si) substrates for graphene growth. Firstly, various growth parameters were varied for optimized growth of high quality and large area graphene without metal catalysts and mask patterns. Raman spectroscopy and atomic force microscope analysis indicated that the grown grapheme is uniform in quality and particularly oriented.(3) Investigation of the electrical properties of graphene. For electrical properties measurements, electron-beam-lithography related techniques were used to fabricate field effect transistors based on monolayer graphene grown on silicon dioxide(Si O2/Si) substrates, room temperature transport characterization measurements indicate that the resulted layers have carry mobility of 6250cm2/(V·s) and 1679cm2/(V·s), respectively, suggesting that our method could potentially be used to grow graphene that suitable for device fabrication without substrate transfer.