Low temperature plasma enchanced chemical vapor deposition of graphene layers

• Κύριος συγγραφέας: Σωτηρίου, Νίκη
• Άλλοι συγγραφείς: Αμανατίδης, Λευτέρης
• Μορφή: Thesis
• Γλώσσα: English
• Έκδοση: 2018
• Θέματα: Graphene layers; Low temperature; Γραφένιο; Χαμηλή θερμοκρασία; 530.427

The subject of this master thesis is the synthesis of graphene layers by Plasma Enhanced Chemical Deposition at low temperature, below 300 ˚C, on both nickel and copper foil. The experimental work is mainly focused on the adjustment of the experimental parameters like temperature, pressure, gas mixture ratio, deposition time and power in order to produce graphene layers with low defect density on nickel foil. Raman spectroscopy is used in order to characterize the deposited materials. In order to produce images of the deposited films, scanning electron microscope (SEM) measurements took place and for further investigation of the surface of the deposited graphene layers, Atomic Force Microscope (AFM) measurements where performed on nickel foil before and after deposition. Finally, to further verify the growth of 〖sp〗^2carbon and the amount of oxygen in our samples, XPS experiments were carried out. The experimental results suggest that the deposited films are graphene oxide layers, since C/O ratio is calculated 5,6 by XPS measurements. Moreover, the average thickness of the deposited graphene layers on nickel after the transfer was measured by profilometer to be 200nm for 10min deposition time, indicating the formation of multilayer graphene oxide film. The presence of oxygen in our experiments is attributed to the fact that our experiments were carried out in a low pressure reactor and the base pressure of the system is in the mtorr region. On the other hand, unlike the synthesis of graphene oxide layers on nickel foil, where large area films where synthesized, the density of nucleation on copper foil is quite low and the deposited films are of small lateral dimensions (nanosheets). We attribute the low uniformity of the deposited films on copper to the absence of thermal annealing of the substrate before deposition.