Controllable Fabrication Of Single-crystalline Graphene And Its Physical Properties

Graphene has attracted enormous interest due to its unique physical and chemical properties.Among the fabrication of graphene method,chemical vapor deposition(CVD)is believed to be a best way to grow a large-scale and high quality graphene.However,Most of CVD-grown graphene has many boundaries grains and high defect,which degrade the physics properties of graphene and hinder the applications of graphene-based devices.Hence,it is a challenge to grow large-scale single-crystalline graphene to meet the requirement of graphene-based devices.This paper systematically studied the controllable growth of large scale single-crystalline graphene.The main work is as below:1.Fabrication of millimeter single-crystalline graphene.The relationship between the graphene crystal morphology,size and the growth condition are systematically studied,which adjusting the morphology of graphene and the growth pressure,then petal-like and hexagonal graphene domain were fabricated.Furthermore,micro-size graphene grains can be achieved with decreasing the methane concentration.On this basic,local preparation of single-crystalline graphene was studied,5mm size single-crystalline graphene was fabricated with further suppress the nucleation density by constructing “copper box” structure.2.Fabrication of single-crystalline graphene array.Designing a commercial printing-assisted vapor deposition method,single-crystalline graphene was fabricated by printing carbon precursor array on copper foil.We also research on the effect of different carbon dots size,before annealing atmosphere types and growth time on forming of graphene.Two necessary conditions of fabrication of crystalline graphene arrays are existence of carbon precursor before growth and nucleation density is less than carbon precursor period.3.Preparation of large-scale graphene by local feeding method.Localization is designed by fabrication of graphene equipment and processes.Then we research on effect of distance between hole and copper substrate,methane concentration,growth time of fabrication of large-scale graphene.Localized supply of carbon source can make graphene growth with a specific range,and the round spot graphene is verified to be a polycrystalline.All in all,this work systematically studied on surface morphology of single crystals,domain size,nucleation density under different conditions,millimeter-size single-crystalline graphene and submillimeter-size graphene array were successfully fabricated.This work provides a new strategy for fabrication of single-crystalline graphene arrays,which is essential for the exploration of graphene-based electronic devices.