Graphene has been found to have a wide range of potential applications owing to its unique physical properties. Whilst pioneering lab-scale experiments have demonstrated and leveraged these interesting properties, there is still a significant gap in performance between the one-off exfoliated hero device characteristics and the average characteristics of a large graphene films suitable for scalable fabrication/manufacturing methods. Graphene films deposited by chemical vapour deposition hold the most promise to exploit the unique properties on industrial scales, yielding mobilities approaching that of the current record holding exfoliated graphene based devices.

In this work three fundamental issues for the production and application of graphene films are addressed. Firstly, the issue of minute catalyst contamination is systematically studied through the use of Raman spectroscopy, image analysis and film etching to characterise the defect density of the graphene film under different parameters. It was found that the current best method of suppressing graphene nucleation density, an oxidative pretreatment to remove carbon contamination, can supply a Cu catalyst with a low level oxygen that was long undetected due to the limitations of common surface measurements. This oxygen is not only shown to increase the defect density of the graphene films, but also to significantly increase the frequency and size of unwanted adlayers in the film. As a result of the study, a simple additional reductive annealing stage was introduced to decrease the oxygen from the Cu foil after it has acted to remove carbon contamination. This new procedure allows for the beneficial effects of the oxygen pretreatment whilst negating any deleterious effects on the final film quality.

The second core problem is the control of the topographical and crystallographic texture of the catalyst. It is generally agreed in the literature that Cu(111) is the ideal growth catalyst to produce the highest quality graphene, yet there is significant difficulty in producing flat single crystal Cu at wafer scale whilst still remaining cost effective. This issue is addressed by designing and optimising an integrated wafer scale deposition process for single crystal Cu on sapphire substrates. Previous work in the area has so far relied on lengthy (10~h) high temperature oxygen annealing of the sapphire or high temperature acid baths. Here a novel in-situ deposition demonstrates that these stages can be skipped entirely once the deposition is optimized, giving a wafer-scale low roughness single crystal Cu(111) film ideal for graphene growth. The process is also demonstrated to be transferable to other targeted orientations of Cu when epi-ready MgO substrates are used, allowing for the optimization of the catalyst texture as an explorable parameter space.

Finally, the question of which crystallographic orientation of catalyst is best for graphene growth and transfer is answered. The ideal graphene transfer method is proposed to be mechanical exfoliation, limiting the contamination of the catalyst that wet-transfer techniques would otherwise cause. Though Cu(111) is thought to be the best orientation for growth, it is notoriously difficult to mechanically exfoliate, so whilst the graphene may be the best quality on catalyst, it would not perform well after it is removed due to transfer-related cracks and other damage. Using extensive image stitching and alignment to correlate the crystallographic orientation of Cu with the oxidation characteristics, Raman characterisation and propensity for transfer, crystallographic (inverse pole figure) maps are created to show which facet of Cu will result in the highest quality post-transfer graphene. The systematic study demonstrates the effects of Cu oxidation on graphene before and after transfer, with Raman spectroscopy allowing for probing the action of the interfacial oxidation as it decouples the graphene from the catalyst. The study sheds light on the complexity of the Cu-graphene-transfer system, but also shows trends and patterns that point towards the ideal catalyst crystallographic orientation that will yield the best quality graphene after a peeling transfer process.