Speaker: Tetyana Ignatova, University of North Carolina at Greensboro
Abstract: Our study of laser irradiation of 2D TMDC samples reveals several stages of alternation of their optical and electronic properties. Upon controllable light irradiation with carefully selected laser power, MoS2 quality improves towards more pristine crystalline structure. This is manifested with increasing A exciton weight in the photoluminescence (PL) spectrum. For multilayered TMDC samples, laser irradiation results in photoinduced etching, down to the single layer thickness, as confirmed by measured separation between E2g and A1g Raman peaks. For all original sample thickness – monolayer or multilayer – PL enhancement is observed, for SiO2 and Al2O3 substrates. This suggests the internal mechanism which is reliant on the material itself rather than an interaction with the substrate.
This work was performed in part at the JSNN, a member of the SENIC and NNCI, (NSF ECCS-1542174) and at the PSU, the 2DCC-MIP (NSF DMR-1539916, the RSVP student support and samples). The work was supported by Department of Defense [Contract W911QY2220006].
Biography: Tetyana Ignatova is an Associate Professor of Nanoscience in the Joint School of Nanoscience and Nanoengineering at the University of North Carolina at Greensboro. She received her M.S. degree in Radiophysics and Electronics from the Kharkiv State University in Ukraine, and her Ph.D. in Physics from Lehigh University. After three years as a postdoctoral associate at University of California Irvine and Lehigh University, she joined the UNCG faculty in 2017. Her research interests focus on engineering optical and electronic properties of novel low dimensional materials.