Synthesis and in situ characterization of graphene on copper substrates

Abstract

This thesis focuses on the synthesis and study of graphene, a rising star on the horizon of materials science with many applications in (bio)electronics, photonics, bioengineering, etc.. Still, a controlled synthesis of good quality graphene on a wafer-size scale remains a challenge. This project takes a first step towards the in situ preparation and characterization of graphene. The growth process, executed under ultra high vacuum, was analysed in situ by different spectroscopy methods. With these experiments we tried to understand the fundamental growth mechanism and catalyst interaction to establish a method for a controlled growth. Next, we examined the influence of an ambient environment on the original chemical character of the graphene layers. Finally, surface treatments were applied to reverse the impact of air-based contaminations while simultaneously trying to avoid extensive damage to the sample morphology. Bilayer and single layer graphene films were formed using methane and hydrogen precursors. We found that graphene reacts with different molecules in the air. These molecules will lower the quality of the sample by forming extra layers on top of the single layer graphene sample. We found that heating to 773 K for five minutes only removes part of the contaminations, while annealing to 973 K allowes to basically restore the original state of a sample. Overall, we managed to form mono- and bilayer graphene, analyse the influence of air exposure on the chemical character and showed that these contamination can