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Kristen Kaasbjerg: Effects of atomic disorder on carrier scattering and transport in two-dimensional MoS2

posted 27 Jul 2015, 01:00 by info admin
K. Kaasbjerg and A.-P. Jauho
Center for Nanostructured Graphene, Dept. of Micro- and Nanotechnology, Technical University of Denmark, 2800 Lyngby, Denmark

Experimental studies of transport in monolayer MoS2 have indicated that atomic disorder such as, e.g., atomic vacancies are the main mechanisms behind carrier scattering in two-dimensional (2D) materials [1-3]. Here we apply an atomistic method for the calculation of the scattering potential due to atomic disorder and study the effect of Sulphur and Molybdenum vacancies (see illustration below) on carrier scattering in 2D MoS2. Due to the three-fold rotational symmetry of vacancy sites, the two types of vacancies are found to give rise to distinctly different intra- and intervalley couplings for scattering inside and between the conduction band K,K’ valleys. From the calculated intra- and intervalley couplings, we calculate the low-temperature, vacancy limited carrier mobility. Our results show that Molybdenum vacancies lead to a strong degradation of the carrier mobility. On the other hand, Sulphur vacancies are strongly screened by free carriers in extrinsic MoS2 and therefore only give rise to a moderate reduction of the carrier mobility. For a S-vacancy concentration as high as ~0.1 %, a low-temperature mobility on the order of 10.000 cm2 V-1 s-1 can be expected.

1. B. W. H. Baugher, H. O. H. Churchill, Y. Yang, and P. Jarillo-Herrero, Nano Lett. 13, 4212 (2013)
2. H. Schmidt, S. Wang, L. Chu, M. Toh, R. Kumar, W. Zhao, A. H. Castro Neto, J. Martin, B. Özyilmaz, S. Adam, B. Özyilmaz, and G. Eda, Nano Lett. 14, 1909 (2014)
3. X. Cui et al., Nature Nanotech. (2015)

Kristen Kaasbjerg is currently visiting postdoc in the group of Antti-Pekka Jauho at the Center for Nanostructured Graphene at DTU where he works on a theoretical method to describe carrier scattering off atomic disorder in two-dimensional materials.