Two-dimensional (2D) molybdenum disulphide (MoS2) has attracted widespread attention in the materials community over the last decade because it exhibits fascinating electronic and optoelectronic properties as outlined in several comprehensive reviews ¹ . MoS2 is usually grown by Chemical Vapour Deposition (CVD) on Si/SiO2; it can be used and studied on Si/SiO2 or after transfer to other substrates.

Two-dimensional MoS2 sheets often exhibit a perfect lattice over large areas but sulphur vacancies are also common both in the sheet and at the sheet edges; S vacancies are in fact crucial for catalysis ³. Grafting molecules to the surface of such a 2D crystal changes the electronic and optical properties because the attached molecules influence the electronic structure of MoS2. Scanning tunneling microscopy studies of the adsorption of dibenzothiophene (DBT) on single-layer MoS2 offered the first direct evidence that it is possible to induce covalent bonding of DBT to MoS2 ⁴.
The purpose of this bachelor project is to study whether one can achieve at the same time a healing of S-defects in a MoS2 monolayer and a change of its optical properties by adsorbing alkane thiol.

The student will first create a higher than usual amount of S vacancies by heating the MoS2 monolayer grown by Chemical Vapor Deposition (CVD) on Si/SiO2 above 200 °C. Then the sample will be immersed into an alkane thiol solution to induce alkane thiol adsorption and hence filling of these vacancies. The success of the attachment will be verified by water contact angle measurements and with X-ray photoelectron spectroscopy. A change of the optical properties of MoS2 will be revealed by UV-Vis Spectroscopy.

BSc Research Project (Both suitable for Physics and for Applied Physics)
Expected Time : 10 weeks
Daily supervisors: PhD students Sumit Kumar and Ali Syari’ati (Surfaces and Thin Films Research Group)
Supervisor: Prof. Petra Rudolf

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