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Identifier

000399720

Title

Photochemical doping of mechanically exfoliated monolayer WS2

Alternative Title

Φωτοχημικός εμπλουτισμός μηχανικά αποφλοιωμένου μονοστρωματικού κρυστάλλου WS2

Author

Δεμερίδου, Ιωάννα Ε.

Thesis advisor

Φωτάκης, Κωνσταντίνος
Στρατάκης, Εμμανουήλ

Reviewer

Κιοσέογλου, Γεώργιος
Άγγλος, Δημήτριος

Abstract

Transition metal dichalcogenides (TMDs) bonded by weak Van der Waals forces between layers, can be mechanically exfoliated to a single layer. These ultrathin materials belong to the family of two dimensional (2D) materials. By reducing the thickness, 2D materials exhibit spectacular optical and charge transport properties. As a result, the exciton-related phenomena, are prominent in TMDs monolayers compared to their bulk counterparts. With tunable bandgaps, 2D TMDs present both fundamental and practical interest. Micro-Raman and micro-Photoluminescence spectroscopy were used to characterize the layered TMD films. The purpose of this thesis is the study of a new photochemical doping technique. A mechanically exfoliated monolayer tungsten disulfide (WS₂), is radiated by a pulsed UV laser in rich chlorine and nitrogen environment in order to further understand the excitonic properties, with different carrier’ densities and as a result, to tune the band gap of the crystal. Both micro-PL and micro-Raman spectra of the doped monolayer WS₂ are affected by this photochemical doping. These remarkable mechanical and optical properties open up many opportunities in the field of optoelectronics. The manipulation of the electrical and optical properties of two dimensional TMDs, is particularly important for developing optoelectronics devices for chemical and biochemical sensing applications. Finally, there is a wide range of applications for energy storage and high performance electronics.

Language

English

Subject

Chlorine

Exciton

Mechanical exfoliation

Nitrogen

Photoluminescence

Raman spectroscopy

Tungsten disulfide

Two dimentional materials

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