Master thesis “Optical properties of Transition Metal Dichalcogenides”

Valentino Jadriško successfully defended his master thesis which he did in the laboratory for optical response under the supervision of his mentor Dr. sc. Nataša Vujičić.

In this diploma thesis experimental setups Raman spectrometer on the Institute of Physics in Zagreb and time resolved photoluminiscence on the Italian Institute of Technology in Milan were used. Samples of monolayer and bilayer MoS 2  grown by method of chemical vapor deposition, and transfered MoS 2 monolayers on SiO 2 /Si substrate were characterized. In the photoluminiscence spectrum of 2D MoS 2 excitons A and B were observed , under increased doping new features emerged in spectrum which were identified as trions. In this thesis  dependence of photoluminiscence spectrum on photo doping were investigated which was accomplished by tuning the laser power from 1 µW to 500 µW with 532 nm wavelength. Under high laser powers and photo doping  domination of trions was observed in photoluminiscence spectra whereas under low laser powers and photodoping excitons are dominant in photoluminiscence spectra. Observed results and dependence of exciton and trion population on photo doping are in corespondence with the published results of electrical and chemical doping. In order to investigate dynamics of photo doping and dependence of exciton and trion populations in time  time resolved photoluminiscence was used.