Subcategory: Materials Science
Quentarius Moore - Jackson State University
Co-Author(s): Lingling Guo, Haoming Yan, and Hung-Ta Wang, University of Alabama, Tuscaloosa, AL
Thermoelectric materials (TMs) have been studied for over a century and manufactured since the 1960s. The research in TMs and applications has seen an awakening of interests over the past decade. This is in part due to new methods and discoveries in materials science. A handful of areas benefitting from thermoelectric material applications include refrigeration, electronics, transportation, and medicine. However, there are still revolutionary applications that are not yet achievable or thought of owing to the fact that the efficacy of TMs do not allow for the ideas to be practical.
Bismuth Telluride (Bi2Te3) is a well-known TM but also is becoming a well-known topological insulator (TI). Topological surface states (TSS) are a quantum state that arises on the surface of TIs. The properties of TSSs results in dissipation-less electronic transport which allows for the feasibility of revolutionizing many energy-related technologies. The main challenge of utilizing TSSs is the lack of methods to open a bandgap at the Dirac cone and to tune the bandgap once it is opened. Elastic strain engineering (ESE) is an attractive method for the opening and tuning of the band gap of van der waals layered materials because elastic deformations can easily be induced in 2D nanosheets.
Chemical vapor transport (CVT) was performed in an attempt to successfully synthesize, and determine the conditions that are favorable for growing, two-dimensional layered nanosheets of Bi2Te3 with controlled thickness and lateral dimensions on mica substrates by van der Waals epitaxy. Atomic force microscope was performed to test mechanical properties of nanosheets and confirm dimensions. We were able to produce nanosheets with a thickness as small as 5 nm. The elastic properties of 5–14 nm-thick Bi2Te3 nanosheets are of interest for the TSS research, because TSSs would hybridize when the thickness of a TI film is thinner than TSSs’ penetration depth (i.e., 5 nm for Bi2Te3). Our successful growth of these 2D nanosheets facilitate the expansion of knowledge of the elastic properties of Bi2Te3 2D nanosheets. These results suggest the feasibility of the ESE of TSS.
References: Li et al. J. Am. Chem. Soc. 2012, 134, 6132-6135 Li et al J. Am. Chem. Soc. 2012 134 (14), 6132-6135 Guo et al. ECS Solid State Lett. 2013 2(2): P19-P21 Kong et al. Nano Letters 2010 10 (6), 2245-2250 Elastic properties of van der Waals epitaxy grown bismuth telluride 2D nanosheets. Guo et al. Nanoscale, 2015, 7, 11915-11921Not Submitted
Funder Acknowledgement(s): I would like to acknowledge the NSF-REU Program (EEC-1358750). This work at the University of Alabama (UA) was supported by the start-up fund (Wang, 2011).
Faculty Advisor: Hung-Ta Wang, firstname.lastname@example.org