Atomic Contact Interface between Scanning Tip and MoS2 : A First-Principles Study
Hochan Jeong a, Yong-Hyun Kim a
a Korea Advanced Institute of Science and Technology (KAIST), South Korea, Korea, Republic of
nanoGe Fall Meeting
Proceedings of nanoGe Fall Meeting19 (NGFM19)
#Sol2D19. Two Dimensional Layered Semiconductors
Berlin, Germany, 2019 November 3rd - 8th
Organizers: Efrat Lifshitz, Cristiane Morais Smith and Doron Naveh
Poster, Hochan Jeong, 411
Publication date: 18th July 2019

Since Cho et al. reported atomic scale resolution of monolayer graphene from thermoelectric scanning images [1], the atomic scale thermoelectric images were explained with coherent Seebeck coefficient and abrupt temperature drop at the tip-sample interface [2]. Although simulated contrast patterns matched very well with experimental images, no atomic scale thermoelectric model for the tip-sample interface has not been studied yet.

Here we unravel the interfacial characteristics with realistic tip and sample models, as the imaging resolution largely depends on the atomic termination of tip apex and their reactivity with the sample surface. The electronic and phonon densities of states as well as optimized configurations were obtained for a variety of tip-sample contact models, such as Au metal, oxygen terminated Au, and H-passivated carbon tips, based on first-principles density functional theory (DFT) calculations. We aim to figure out the height contrast of tip on each site, corresponding to experimental topography images, by investigating the energy profile as a function of distance. As a result, hydrogen passivated diamond tip was regarded as appropriate in the weak coupling region. This result would help us to understand the height profiles obtained in Scanning Seebeck Microscopy and estimate the effective temperature drop affected by local bond strength.

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