Molecular modification of graphene conductivity
Research on the wonder-material graphene led to a Nobel Prize in Physics in 2010. Its unique strength, flexibility and electrical conductivity offer tremendous potential for use in miniaturised transistors. However, unlocking that potential requires bandgap engineering to control the properties determining how mobile charge carriers are produced.Graphene is a zero-bandgap semiconductor. Scientists investigated the potential of modifying graphene layers with various atoms or molecules to modify the bandgap and control semiconductor properties with EU funding of the project 'Bandgap engineering of graphene by molecular self-assembly' (BENGRAS).The team developed and built its own Raman microscope to study the spectroscopic (energy) properties of modified graphene. Using it in combination with conventional atomic force microscopy, investigators were able to correlate the Raman spectra of individual graphene nano-ribbons with their morphologies. Doping of one material with another is often used to change electrical properties, so scientists investigated adsorption of a known electron donor molecule (n-dopant). Preliminary results suggest a doping effect of the molecule on graphene sheets.Nano-structured semiconductor materials are poised to revolutionise fields from biomedicine to optoelectronics and just about anything in between. BENGRAS provided important methodologies for modifying the surface structure and thus electrical properties of graphene. Together with measurement techniques to correlate morphology with conductivity, the team has made an important contribution to the EU's ability to exploit this novel material in real innovations that will benefit the economy and the public in general.
Graphene, Raman microscope, bandgap, doping effect, miniaturised transistor, semiconductor