Transition Metal Dichalcogenides for Electronic Applications and for Investigations of Surface Activity

Tuesday, April 1, 2014 - 3:30pm - 5:00pm
Regents 109
Ludwig Bartels
University of California, Riverside

Transition metal dichalcogenides (TMDs) such as MoS2 have attracted widespread attention because they combine some of the fascinating properties of graphene, such as stability at the monolayer limit and well-defined transport properties, with native semiconducting and direct-bandgap behavior. MoS2 has proven to be almost as stabile as graphene and it can be prepared at significantly lower temperatures which are compatible with patterned Si/SiO2 substrates. In the second part of my talk, I will describe methods of CVD fabrication of single layer TMDs and their alloys using organic chalcogen precursors.1 I will also describe the ensuing properties of the alloy materials. MoS2 is also the key compound in industrial hydrodesulfurization of gasoline for automotive applications. In the first part of my talk, I will address the growth of molybdenum-sulfur compounds on a Cu(111) surface. In particular, we find a range of non-MoS2 surface structures and characterize their interaction with oxygen-containing adsorbates such as anthraquinone and formic acid. The highest binding affinity is found for a surface structure that is identified as Mo2S3, and not for the edges of MoS2 islands, to which typically activity of MoS2-based catalysts is attributed.2

1. Mann, J., Ma, Q., Odenthal, P.M., Isarraraz, M., Le, D., Preciado, E., Barroso, D., Yamaguchi, K., Son, G.v., Nguyen, A., Tran, T., Wurch, M., Nguyen, A., Klee, V., Bobek, S., Sun, D., Heinz, T.F., Rahman, T.S., Kawakami, R. & Bartels, L. 2-Dimensional Transition Metal Dichalcogenides with Tunable Direct Band Gaps: MoS2(1-x)Se2x Monolayers, Adv. Mater., DOI: 10.1002/adma.201304389 (2013).
2. Sun, D., Lu, W., Le, D., Ma, Q., Aminpour, M., Alcántara Ortigoza, M., Bobek, S., Mann, J., Wyrick, J., Rahman, T.S. & Bartels, L. An MoSx Structure with High Affinity for Adsorbate Interaction, Angewandte Chemie 124, 10430-10434 (2012).

Host: Paola Barbara
Discussion Leader: Paola Barbara