Towards formation of graphene on Cu(110) surface from thermal decomposition of perylene

• Main Author: Rasonabe, D. T.
• Published: University of Liverpool 2016
• Subjects: 547
• Online Access: https://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.721974

This thesis spans three different topics of experiments based on measurements from low-energy electron diffraction (LEED), reflection-absorption infrared spectroscopy (RAIRS), and scanning tunneling microscopy (STM). The first topic is related to studies of the structure of perylene on the Cu(110) surface, in the interest of main applications in electronics and optoelectronics. The RAIRS measurements show chemisorption of perylene molecules in direct contact to the Cu(110) surface based on red-shift in the vibrational frequencies. The appearance of two sets of red shifts for the same set of vibrational modes supports the proposed model for the commensurate (5x5) superstructure from a past report. STM measurements of monolayer growth at room temperature, in conjunction with simple two-dimensional models, show co-existence of chiral commensurate superstructures, (5x5) superstructure, and (8x5) superstructures. The analysis suggests the most stable adsorption site for perylene on the Cu(110) surface is the atop site. The second and main topic is related to studies of the structure of graphene formation on the Cu(110) surface at low and high growth temperatures, in the interest of fundamental studies of graphene-metal interfaces and to develop a simple synthetic method. The synthetic method is based on thermal decomposition of a hydrocarbon, but the process is unique from those in reports so far because the hydrocarbon used is the complex-molecule perylene, in contrast to a simple aliphatic hydrocarbon. The effectiveness of the conversion to graphene exceeds 50%. LEED measurements show increase in growth temperature develops the graphene formation from disordered epitaxial orientation towards the most stable epitaxial orientations at ±5° but cannot eliminate the partial disorder from less-stable epitaxial orientations around │±19°│ - │±30°│. Furthermore, direct visualization from STM measurements shows increase in growth temperature develops the graphene formation from percolated network of minute graphene domains and clusters into large domains in isolated islands. STM measurements also show the Moiré superstructures of graphene on the Cu(110) surface are chiral, a characteristic of importance to applications in enantioselective catalysis and chiral resolution. Simple two-dimensional models are shown to be able to estimate the epitaxial orientation of graphene from the Moiré pattern. The statistical distribution of epitaxial orientation from the STM data shows another preference for some orientation somewhere between │±25°│ and │±30°│ exists, second to the most preferred orientations at ±5°. The third topic is related to STM characterization of a Co-TPP overlayer on sub-monolayer graphene on the Cu(110) surface, in the interest of integration of graphene to organic materials and functionalization of graphene. The growth of the Co-TPP overlayer shows the adsorption on top of graphene is weaker than the adsorption on bare Cu(110) surface. Co-TPP forms self-assembled superstructures on top of graphene. The self-assembled Co-TPP superstructures demonstrate self-healing character.