A STUDY ON THE CHEMICAL VAPOUR DEPOSITION METHOD OF GENERATING GRAPHENE

Chemical VapoV Deposition (CVD) is a viable technique for fabrication of large areas of graphene. CVD fabrication is the most prominent and common way of fabricating graphene in industry. The main goals of this work are to explore the graphene growth mechanics in a low pressure cold-wall CVD system on a copper substrate and optimize the process of growing high quality graphene in terms of carrier mobility, and crystal structure. Optimization of a process for graphene growth on commercially available copper foil is limited by the number of aluminium oxide particles on the surface of the catalyst. By replacing the copper foil with a thin deposited copper film on a SiO2/Si or cplane sapphire wafer the particles can be eliminated. Typical strategies for controlling the temperature during CVD fabrication of graphene are proportional, integral, and derivative (PID) controllers. The P1U controller in a CVD system works off feedback temperatures from a thermocouple. The thermocouples used in this work suffer from degradation at the temperatures and the hydrogen gasses needed for high quality graphene growth. The degradation of thermocouples leads to large variations in the grown graphene. This was solved by controlling the temperature through applying a set power to the heat source, resulting in a more stable temperature from process to process. Copper foil was found to exhibit a polycrystalline surface with a predominantly Cu(OOI) orientation, through electron backscatter diffraction mapping. Copper thin film deposited on a Si02/Si wafer display a polycrystalline nature with the Cu(111) orientation dominating, when the crystals increase in size. Copper thin film sputtered on a c-plane sapphire wafer shows almost single crystal formation of Cu (111) across a 4 inch wafer. Preliminary results show the highest carrier mobility was achieved from graphene grown on copper on sapphire, while graphene grown on copper foil showed the lowest carrier mobility.