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conferenceseries.com
March 20-22, 2017 Orlando, USA
3rd International Conference on
Smart Materials & Structures
Volume 6, Issue 2 (Suppl) J Material Sci Eng
ISSN: 2169-0022 JME, an open access journal Smart Materials 2017
March 20-22, 2017
Electronic and optical properties of transition metal dichalcogenides in the presence of vacancy defects
Michael N Leuenberger1, M A Khan1,2, Mikhail Erementchouk1,3 and Joshua Hendrickson4
1University of Central Florida, USA
2Federal Urdu University of Arts, Science and Technology, Pakistan
3University of Michigan, USA
4Air Force Research Laboratory-Wright-Patterson Air Force Base, USA
Single layer (SL) transition metal dichalcogenides (TMDCs) (MX2; M=transition metal such as Mo, W and X= S, Se, Te) have
attracted a lot of attention due to their intriguing electronic and optical properties. SL TMDCs are direct band gap semiconductors,
which can be used to produce smaller and more energy efficient devices such as transistors and integrated circuits. Moreover, the
band gap lie in the visible region, which makes them highly responsive when exposed to visible light, a property with potential
applications in optical detection. In contrast to graphene, SL TMDCs exhibit large spin-orbit coupling (SOC) originating from the d
orbitals of the transition metal atoms. The presence of the giant SOC makes them great candidates for exploring spin physics and for
spintronic devices. Defects usually play an important role in tailoring electronic, optical and magnetic properties of semiconductors.
We performed standard first-principle study to evaluate the electronic and optical properties of single-layer (SL) transition metal
dichalcogenides (TMDCs), in the presence of vacancy defects (VDs). We consider three types of VDs in SL TMDCs (1) X-vacancy,
(2) X2-vacancy, and (3) M-vacancy. We find that VDs lead to localized defect states (LDS) in the band structure, which in turn
give rise to sharp transitions in in-plane and out-of-plane optical susceptibilities, χΠ and χ⊥, respectively. The effects of spin orbit
coupling (SOC) are also considered. We find that SOC splitting in LDS is directly related to the atomic number of the transition metal
atoms. Apart from electronic and optical properties we also find magnetic signatures (local magnetic moment of ~µB) in MoSe2 in the
presence of Mo vacancy, which breaks the time reversal symmetry and therefore lifts the Kramers degeneracy. We use group theory
to derive the optical selection rules for both χΠ and χ⊥.
Biography
Michael N Leuenberger has received his PhD degree in Theoretical Physics in 2002 from the University of Basel in Switzerland. After his Postdoctoral positions at the
University of Iowa and at the University of California, San Diego he joined in 2005 the NanoScience Technology Center at the University of Central Florida and became
tenured Associate Professor in 2011. In 2008, he has received the DARPA/MTO Young Investigator Award. His current research areas include quantum information pro-
cessing in topological insulators, optoelectronics in 2D materials and solar energy harvesting in nanoparticles. He has published more than 60 peer-reviewed papers and
4 book chapters.
Michael N Leuenberger et al., J Material Sci Eng 2017, 6:2 (Suppl)