GAS SENSORS AND STUDY OF NEW DEVICES BASED IN GRAPHENE

• Grant number: 09/17111-4
• Support Opportunities: Scholarships in Brazil - Post-Doctoral
• Start date: July 01, 2010
• End date: June 30, 2013
• Field of knowledge: Engineering - Electrical Engineering
• Principal Investigator: Antonio Carlos Seabra
• Grantee: Luis Enrique Gomez Armas
• Host Institution: Escola Politécnica (EP). Universidade de São Paulo (USP). São Paulo , SP, Brazil

Abstract

With this research project we aspire to develop the fabrication of gas sensors based on graphene (graphite atomic layer) of micro-nano size, which are capable of detecting individual events when a gas molecule attaches to or detaches from graphene`s surface. The operation principle of these sensors (devices) can be explained through changes on their electrical resistivity when the gas is in contact with the graphene`s surface. These devices will be fabricated from monolayer and bilayer graphene of different geometries, which will properly be identified by the characterization techniques, Raman and Atomic force Microscopy. After this, using optic and electron beam lithography the device geometry and electric contacts will be made on the graphene devices. When the devices are fabricated, before passing to more sophisticated measurements, that is, as a function of time, preliminary experimental measurements will be performed to verify the quality of the electric contacts. For this purpose, measurements of the source-drain current (Isd) as a function of the source-drain voltage (Vsd) and gate voltage (Vg) will be performed, expecting a linear behaviour and a V type format, in this last case appears the called Dirac point (VDirac); it will also be verified if "the graphene is doped by the gas", performing Isd x Vg before and after the sensor being exposures to the gas. Results obtained by several research groups have shown that, gas sensors based in graphene are capable of detecting toxic gases by quicker and efficient ways than conventional gas sensors [1, 2, 3, 4]. Taking into account these advances achieved up to now, our contribution will be focused to prove the viability of gas sensors based in monolayer and bilayer graphene to verify their repetition and reproduction. This could be the beginning of the fabrication of these sensors in a reproducible manner, which will mean a great technological advance on the area. We also aspire, with this project, to achieve the development of new devices based in graphene (transistors), as well as magnetotransport measurements at low temperature to study quantum effects and the energy gap (Eg) of the devices.