AbstractsEngineering

In 2004 there were newly conditions for a scientific revolution, with very important technology implications and yet to be completely developed. It is the isolation of atomic carbon layers, better known as graphene, whose extreme mechanical and electronic properties stand out above all known materials: it presents the highest electron mobility, ambipolarity, it supports large current densities, the highest elastic modulus, increased thermal conductivity, it shows high impermeability, and reconciles fragility and ductility. The study of graphene was about to be the next step to the boom in nanotechnology. In this case, the system to consider is purely two-dimensional, being the thinnest structure known to date. In 2010, this discovery was acknowledged with the Nobel Prize to the scientists A. Geim and K. Novoselov from the Manchester University (UK). The goal of the project, in which this thesis was framed, is to develop new materials in ultrathin structures of few monoatomic layers, based on graphene, with extreme surface properties (very high wear resistance, ultra low friction and surface energy, extreme chemical resistance, biocompatibility) for biomedical applications. The scope of this objective is to overcome the limitations of current techniques in terms of the growth surface of graphene (of some .m2) and to extend the possible applications of graphene to systems and devices requiring macroscopic size surfaces. For this purpose, the thesis had different tasks consisting of: a) The design and construction of a new high vacuum reactor in the Clean Room of the Universitat de Barcelona that works with high-temperature chemical vapor deposition (CVD) and magnetron sputtering. b) Study of the principles of a CVD process of graphene on metals, and development of a modified CVD method based on pulses of gas (methane), which will reduce the current deposition times to 1-10 s, pressure of 10-4 Pa, quantity of precursor gas needed, and temperature (900-1000 °C), to grow high quality graphene. c) Fabrication of graphene layers on metal substrates, sputtered copper/nickel and copper foils, of large area and high quality by this modified CVD technique, focusing on obtaining the material as effectively as possible towards an implementation on applications. d) Characterization of the graphene obtained through different techniques in order to optimize its physical and surface properties, as well as the CVD method; such as structural and morphological studies by Raman spectroscopy, SEM and Optical Microscopy. In addition to a transfer process from copper to silicon. e) Fabrication and characterization of graphene layers by means of mechanical exfoliation of graphite on silicon in order to characterize the electrical properties to fabricate a graphene-based FET. Exfoliated samples were also used to study the effect of the SHI irradiation with glancing angles on the surface. The thesis is then, divided into four main parts. The Part I will introduce the state of the art of graphene as novel material and its…