Discipline: Technology and Engineering
Subcategory: Materials Science
Carolina Navarro - The Pennsylvania State University
Co-Author(s): Natalie Briggs, The Pennsylvania State University, PA, Ana De La Fuente Duran, The Pennsylvania State University, PA, Dr. Joshua Robinson, The Pennsylvania State University, PA
In the world of technology, 2D materials have become a key component in the development of electronics, as they have been shown to enhance performance and minimize energy use. Such elements that play important roles in this world are silicon, from which silicon carbide is derived and carbon from which graphene is obtained. This is due to their semi-conducting abilities and physical factors such as transparency and strength. The insertion of atoms into a crystal lattice, in this case, epitaxial graphene is called intercalation and it is a relatively new method of confinement. This process of diffusion across layers is crucial to learn more about as its properties prove potential for supercapacitors and overall tunability of physical properties in semi-conducting materials.
Recently, the Robinson group has investigated the intercalation of tin via epitaxial graphene as it is believed that this element experiences a change in electrical properties when confined, such as superior electrical conductivity. Yet the intercalation of tin does not occur at all temperatures, thus the research on discovering the best temperature for successful intercalation became the main focus. The method of intercalation involves plasma treating epitaxial graphene in order to induce defects which would later serve as entrances for the metallic source chosen, in this case being tin, to seep through. The treated epitaxial graphene is placed face-down over a small sample of tin all within a ceramic step-crucible, which is then inserted into a quartz tube furnace pumped with argon gas. The furnace is then programmed to run a specific heating curve, in which it must ramp up at 20 degrees per minute until the desired temperature is reached. This temperature is held for thirty minutes. The sample is then quenched to room temperature and analyzed for visible signs of intercalation via several forms of characterization.
The results have been quite promising as intercalation was found within the samples that were heated at a lower temperature rather than at a higher temperature. This was revealed via Atomic Force Microscopy as particulates of tin were identified along the step edges of the graphene and X-ray Photoelectron Spectroscopy allows one to see the bonding environments, in which at lower temperatures, signs of intercalation are portrayed through peak splitting of C 1s spectra. The Raman Spectroscopy revealed D, G, and 2D vibrational modes of graphene, with a noticeable decrease in the 2D peak at the higher temperatures, leading to deintercalation. The successful intercalation of tin has sparked a curiosity in using this method on elements of higher melting points and other properties. The use of lead for intercalation is a project that is of interest in moving forward with as it is a type 1 superconductor and the focus on spintronics may change the world of technology as we know of it today, leading to such possibilities as ultra-low power transistors and superconductors.
Funder Acknowledgement(s): I would like to thank the National Science Foundation EFRI REM (EFMA-1433378 and EFMA-1433307) for funding this research project
Faculty Advisor: Joshua A. Robinson, firstname.lastname@example.org
Role: As an undergraduate researcher within the Robinson group, I was involved in developing the various heating curves for the tin sample runs. I also took part in the intercalation process which included the loading of the sample on the ceramic crucible and placing the graphene atop. Characterization was another aspect of the research that I was heavily involved in, as I often ran the intercalated samples through the Atomic Force Microscopy and X-Ray Photoelectron Spectroscopy in order to analyze if the sample intercalated or not and how well it intercalated.