14 research outputs found
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Growth of continuous graphene by open roll-to-roll chemical vapor deposition
We demonstrate the growth of high-quality, continuous monolayer graphene on Cu foils using an open roll-to-roll (R2R) chemical vapor deposition (CVD) reactor with both static and moving foil growth conditions. N2 instead of Ar was used as carrier gas to reduce process cost, and the concentrations of H2 and CH4 reactants were kept below the lower explosive limit to ensure process safety for reactor ends open to ambient. The carrier mobility of graphene deposited at a Cu foil winding speed of 5âmm/min was 5270â6040âcm2âVâ1âsâ1 at room temperature (on 50âÎźmâĂâ50âÎźm Hall devices). These results will enable the inline integration of graphene CVD for industrial R2R production.The authors acknowledge funding from the EC project GRAFOL, grant 285275 and EPSRC grant Graphted EP/K0166636
Transport in polymer-supported chemically-doped CVD graphene
In this study we report on the electron transport in flexible-transparent polymer supported chemically doped chemical vapour deposited (CVD) graphene.Oppenheimer Resaerch Trus
Raman spectral indicators of catalyst decoupling for transfer of CVD grown 2D materials
Through a combination of monitoring the Raman spectral characteristics of 2D materials grown on copper catalyst layers, and wafer scale automated detection of the fraction of transferred material, we reproducibly achieve transfers with over 97.5% monolayer hexagonal boron nitride and 99.7% monolayer graphene coverage, for up to 300 mm diameter wafers. We find a strong correlation between the transfer coverage obtained for graphene and the emergence of a lower wavenumber 2Dâ peak component, with the concurrent disappearance of the higher wavenumber 2D+ peak component during oxidation of the catalyst surface. The 2D peak characteristics can therefore act as an unambiguous predictor of the success of the transfer. The combined monitoring and transfer process presented here is highly scalable and amenable for roll-to-roll processing
Case studies of electrical characterisation of graphene by terahertz time-domain spectroscopy
Graphene metrology needs to keep up with the fast pace of developments in graphene growth and transfer. Terahertz time-domain spectroscopy (THz-TDS) is a non-contact, fast, and non-destructive characterization technique for mapping the electrical properties of graphene. Here we show several case studies of graphene characterization on a range of different substrates that highlight the versatility of THz-TDS measurements and its relevance for process optimization in graphene production scenarios