The overarching goals of this project are to establish a culture of research in materials science at the University of the Virgin Islands, and to contribute to enhancing the infrastructure for integration of research and education at this undergraduate institution. The research objectives of the project are to understand doping mechanisms in graphene, to perform annealing studies to investigate if the microstructure of graphene can be modified to determine conditions that lead to more permanent doping effects in the material for device applications, and to develop a quantitative understanding through computational modeling and simulations. The research on understanding electrochemical and electronic doping mechanisms in graphene will advance the knowledge of properties of graphene for electronic and sensor device applications.
This project will demonstrate p-type doping of graphene by surface modification with tetrafluorotetracyanoquinodimethane (F4-TCNQ). F4-TCNQ has been widely used in organic light-emitting diodes to reduce the hole injection barrier by forming a narrow space-charge region near the metal contact, thereby improving device performance. Modifying the graphene surface with F4-TCNQ is therefore expected to favor electron transfer from graphene to F4-TCNQ molecules, leading to an electron accumulation layer in F4-TCNQ and a depletion layer in the graphene, thereby achieving p-type doping of the graphene.
The second task of this project is to investigate the effects of transition metals (TM) as potential electronic dopants in graphene using a chemical vapor deposition system. The doping studies will be complimented with carrier transport measurements. The project intends to find a correlation between the desired amount of doping, the concentration of atoms and their arrangement on the surface. A series of annealing experiments will be performed in order to determine whether or not the doping effect is still present. Lastly, it will be determined which mechanism is best suited for n-type and p-type doping and which set of conditions are most favorable for graphene to maintain its doped state.
