Estudo das alterações das propriedades elétricas e morfológicas do grafeno na presença de gases, nanopartículas e líquidos

Abstract

This thesis involves the changes on the electrical and morphological properties of graphene and bilayer graphene when in contact with diferent environments and subject to diferent conditions. The studies can be grouped in three distinct directions. The frst one focuses on the exposure of a bilayer graphene to gases in a feld efect transistor conguration. The studies consist of a graphene device under the exposure of hydrogen and oxygen atmospheres as a function of temperature. The charge scattering mechanisms presented in the system are also investigated by analysing the changes in the charge neutrality point (CNP), in the minimum of conductivity and in the electron and hole mobilities. The analyses are based on the Boltzmann theory of difusive electronic transport where the short-range (ressonant) and long-range (Coulomb) scattering mechanisms are identified. The second one is related to the modification of monolayer graphene (exfoliated and CVD graphene) with the purpose of producing graphene nanochannels by two diferent methods. One of them was developed in Brazil and consists of a catalytic process that etches exfoliated graphene by thermally activated nanoparticles. The other one was developed at Cornell University (USA) and consists of sculpting CVD graphene by using a pulsed laser ablation technique.Finally, the process and the design to build a platform for achieving suspended CVD graphene windows in contact with diferent liquids are presented. The platform was designed based on a buried channel microuidic structure. This project was also developed at Cornell University (USA).