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EP01.03.18 : Structural, Chemical and Electronic Properties of 1T-SnS2

5:00 PM–7:00 PM Apr 3, 2018

PCC North, 300 Level, Exhibit Hall C-E

Description
Zafer Mutlu1 Ryan Wu2 Bishwajit Debnath1 Mihri Ozkan1 Roger Lake1 K. Andre Mkhoyan2 Cengiz Ozkan1

1, University of California, Riverside, Riverside, California, United States
2, University of Minnesota, Twin Cities, Minnesota, United States

Herein, we have reported on structural, chemical and electronic properties of two-dimensional (2D) tin disulfide (SnS2) crystals grown on silicon dioxide (SiO2) substrates by vapor-phase method. High-resolution annular dark-field (ADF) scanning transmission electron microscope (STEM) analysis indicate that the SnS2 crystals crystallize in 1T phase, which is in consistent with the ab-initio density functional theory (DFT) calculations predicting that SnS2 stabilizes 1T phase at ground state. Photoluminescence (PL) and ultraviolet-visible (UV-vis) spectroscopy measurements suggest that the SnS2 crystals have an indirect band gap of 2.20 eV and 2.35 eV, respectively, which is in good agreement with the DFT-calculated band gap of 2.31 eV. The electrical transport measurements performed on back-gated field-effect transistors (FETs) exhibit n-type semiconductor characteristics of the SnS2 crystals. High-angle annular dark-field (HAADF) STEM imaging and STEM energy dispersive X-ray (EDX) chemical analysis demonstrate that the SnS2 crystals are chemically homogeneous with a stoichiometric S/Sn atomic ratio of 2. Electron energy loss spectroscopy (EELS) and X-ray photoelectron spectroscopy (XPS) analysis present the characteristic Sn and S peaks of SnS2, confirming the phase purity of the SnS2 crystals. Ultraviolet photoelectron spectroscopy (UPS) measurements of the SnS2 crystals provide an ionization potential of 7.51 eV, which is in a perfect agreement with the DFT-calculated ionization potential of 7.51 eV. Resonance Raman spectroscopy in conjunction with ab-initio DFT calculations reveal the characteristic first-order and second-order Raman modes of 1T phase of the SnS2 crystals. Angle-resolved polarized Raman spectroscopy (ARPRS) mappings with different polarization angles show unique edge features of the SnS2 crystals.

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