Subcategory: Materials Science
Nakeshma Cassel - University of the Virgin Islands
Co-Author(s): Wayne Archibald, University of the Virgin Islands, St. Thomas, USVI Sharadha Sambasivan, Suffolk Community College, Selden, NY
Graphene has a potential to serve as a universal contact in next generation electronic devices based on graphene-metal interaction and hetero-stack of 2D materials. The work presented here explores the electronic structure of transition metal oxide, sulfides with graphene as these composites have numerous applications as a super capacitor due to its high power density and porosity. In addition, graphene has been incorporated with insulators such as MoS2 and boron nitride in unique assembly called Vanderwaal materials which has a potential to serve as optoelectronic device due to its tunable conductivity and mechanical flexibility. Researchers have struggled to build graphene-based devices because the material possesses no band gap which enables the material to behave as a conductor. A sizable band gap in graphene is a very important consideration for its incorporation in devices such as transistors because of the presence of charge carriers and the control of their type and concentration are required. In an effort to combat this problem, a band gap was engineered via chemical doping making graphene either p-type or n-type. Primary spectroscopic technique that was utilized for this study was confocal Raman spectroscopy, X-ray photoelectron spectroscopy (XPS) and atomic field microscopy (AFM). Single layer chemical vapor deposition (CVD) graphene samples were doped with 1Å of gold, 1Å of chromium and 1Å of titanium via thermal/e-beam evaporation. Raman Spectroscopy of single layer CVD graphene doped with chromium indicated that it is n-type due to the peak at 1350cm-1 which is characteristic charge transfer peak. Additionally, titanium and gold doped Raman samples indicated that they are both p-type. Further analysis via Photoluminescence Spectroscopy (PL), Near edge x-ray absorption fine structure (NEXAFS) will determine the band gap, chemical nature of Graphene-metal interaction to create required size of the engineered bandgap.
Funder Acknowledgement(s): This project was supported in part by the National Science Foundation Grant DMR -1420634.
Faculty Advisor: Wayne Archibald, firstname.lastname@example.org
Role: This project investigated the electronic and morphological structural changes in transition metal doped graphene. For this project, I used the Thermal/E-beam evaporator to deposit 1 Angstrom thick layers of Gold, Chromium, and Titanium onto single layer chemical vapor deposition (CVD) graphene samples. Additionally, I investigated the doping type (electron or hole doping) of transition metal doped graphene via Raman spectroscopic techniques. Also, I determined the surface roughness of each transition metal doped single layer CVD graphene samples using the Atomic Force Microscope (AFM).