Study of Local Density of States in MoS2 Nanosheets by Scanning Tunneling Spectroscopy

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hosseini, ali | 2015

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Type of Document: M.Sc. Thesis
Language: Farsi
Document No: 48061 (04)
University: Sharif University of Technology
Department: Physics
Advisor(s): irajizad, Azam
Abstract:
Recently, the applications of two dimension materials have been increased in nanotechnology. Among this group of material the Transition metal dichalcogenide due to their energy gap and their particular optical features has attracted much attention. For instance MoS2 is a most famous material in this familyand as a semiconductor has an indirect energy gap about 1.3 eV in the bulk status and 1.9 eV in monolayer. In this project, we investigated the Nano-sheet optical properties of MoS2 by using of tunneling spectroscopy. In this procedure a thin probe is close to the surface until a quantum tunneling occurs between the probe and the sample. By measure the tunneling current we can achieve much information such as electron’s density states of the sample. In this thesis we calculated the thickness effect of MoS2 layers on energy gap and demonstrated when the thickness is reduced, the energy gap increases. Moreover, we evaluated the effect of ethanol gas on electron’s density states and have seen that ethanol enhances the charge carriers. At the end, the effect of light on tunneling current assayed that shows an augmentation in the presence of light
Keywords:
Tunneling Spectroscope ; Scanning Tunneling Spectroscopy ; Two Dimentional Materials ; Metal Transition Chalcogenide

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