Deposition of hybrid structures of reduced graphene oxide and tin dioxide thin films, and persistent photoconductivity observation

Abstract

Reduced graphene oxide (rGO) is deposited on glass substrate by dripping and sol-gel-coating methods giving rise to nanostructures. When in combination with thin films of SnO2, they form a heterostructure SnO2:2 at% Eu/rGO, which alters the surface electrical conductivity. SnO2 and rGO were also combined as a composite, with conductivity strongly affected by ultraviolet excitation, and shows persistent photoconductivity (PPC) phenomenon even very close to room temperature. Both sort o hybrid structures can be applied in electronic devices. The SnO2 films are deposited via chemical route by sol-gel or by a mixed technique that combines powders generated by drying the sol-gel solution with resistive evaporation of this powder. Resistivity measured as a function of temperature show that the SnO2:2 at%Eu sample behaves very similarly to the SnO2:2 at%Eu/rGO heterostructure sample, with the same energy level for the dominant defect, 172 meV, coincident with ionization of oxygen vacancies. Despite not changing the position of this level, the presence of rGO on the surface of the SnO2 film induces a decrease in conductivity in vacuum, demonstrating the surface interaction.