The study also shows that the system studied (graphene sheet on oxidized silicon carbide with intercalated metal layer) can be a good platform for engineering electronic properties. Finally, the team verified that the “doping” effect (the change in the concentration of electrons and holes) can be enhanced by the application of an external electric field, perpendicular to the interface between the graphene and the substrate.īased on these evidences, which were obtained mainly through computational simulations based on the Density Functional Theory, the paper suggests a way to control the concentration and flow of electrical charges on graphene sheets on silicon carbide substrates.
#SILICIO METAL O NO METAL SERIES#
This two-dimensional map series shows the concentrations of electrons and holes in the graphene sheet in the two graphene systems on the silicon carbide surface finished in Si and terminated in C in the presence of an aluminum monolayer and the other containing a gold layer. As a result, conductive channels are formed on the surface of the Si2O5, through which the charges flow. In addition, the gold and aluminum atoms embedded in the Si2O5, which is semiconductor, induce the formation of conducting regions on the surface of this layer, in which the excess of electrons or holes is concentrated, induced by the presence of gold or aluminum, respectively. The researchers verified that the presence of the metallic layer modulates the concentration of the positive (so-called holes) and negative (the electrons) charge carriers in both the graphene sheet and Si2O5. Finally, in order to understand in detail the effect of the insertion of metallic atoms into this type of materials, the scientists added to the simulated system a layer of gold or aluminum atoms embedded in the oxide layer (in this case, Si2O5) in the interface region with graphene. Given that in the production of graphene the presence of oxygen usually oxidizes the surface of the silicon carbide, the Brazilian scientists included in the simulations a layer of silicon oxide between the graphene and the substrate.
In this system, graphene remains attached to the substrate without chemical bonds, by means of distance-dependent weak attraction forces, called Van der Waals forces. In the study that was recently reported in the scientific journal Carbon (impact factor 7,466), the Brazilian team investigated the structure and electronic properties of a graphene sheet on a silicon carbide (SiC) substrate – material often used to deposit or grow graphene.
Representation of the studied system: graphene sheet on substrate of oxidized silicon carbide with layer of intercalated metallic atoms (in this case, gold). The method is similar to the doping of silicon, practiced routinely in the manufacture of semiconductors for the electronics industry. Some of them are based on the insertion of small amounts of metallic atoms that modulate the electronic properties of the material without impairing the other characteristics.
Solutions have been proposed to overcome this technological limitation of graphene. However, it is still difficult to control the concentration and flow of electric charges in graphene, which limits its use in electronics. It is also an excellent conductor of heat and electricity. In fact, graphene is an extremely tough, lightweight, flexible and transparent material. Solutions to this challenge can make a difference in the development of two-dimensional electronic devices – a dimension in which graphene, the one-atom thick network of carbon atoms, stands out for its properties. Controlling the electronic properties of graphene on silicon carbideĪ Brazilian scientific team performed a study based on supercomputer simulations that reveals a way to overcome the challenge of controlling the electronic properties of graphene.