Developing epitaxial graphene for the purpose of nanoelectronics

Work presented here has been centered around the growth of epitaxial graphene via the thermal decomposition of 4H silicon carbide wafers. Improvements to ultra high vacuum growth procedures used within the research group have been made via the optimization of annealing times and temperatures. The optimization involved the use of surface
science techniques such as low energy electron diffraction, atomic force microscopy, low energy electron microscopy and Raman spectroscopy amongst others to monitor changes in surface reconstructions, lateral grain sizes of graphene domains and graphene coverage on the surface as the growth parameters were varied.

Improvements observed via the surface science techniques such as increasing the lateral domain grain sizes from 10s nm to 100s nm and increasing the graphene film coverage were linked to the betterment of the electronic properties of the graphene films (electronic measurements carried out by Graham Creeth), this linking lead to published work. The mechanical properties of these films were also measured
via the use of Raman spectroscopy to probe the formation of strains within the graphene and compare growth carried out on the silicon carbide (000�1) face to literature work carried out on the (0001) face to show evidence of graphene-substrate decoupling within the films grown here, this work also lead to a publication.

Alternate growth procedures have also been investigated. This involved carrying out annealing processes in inert argon gas atmospheres. Atomically terraced substrates were produced via annealing in argon gas atmospheres at temperatures of ~1500°C. These terraced substrates where then subsequently graphitised by increasing the annealing
temperature to ~1600°C allowing for a single stage substrate
preparation and graphitisation process. A result not published elsewhere.

A Nanoprobe system has been used to manipulate the graphene films grown under argon atmosphere and make 4-probe electrical transport measurements allowing sheet resistance measurements to be made.