The main motivation for this project is to explore the gas sensor response and transport mechanism of tin oxide-based nanostructures through the solid-gas interactions study on individuals SnO, Sn3O4 and SnO¬2 nanobelts, with different diameters, against oxidizing and reducing gases. SnO2-based sensors are already well established in the literature, but thermodynamically less stable oxides (SnO and Sn3O4) lack additional studies to explain their changes in electrical conductivity. Study devices in the form of individual nanostructures eliminates the contribution of potential barriers in the grain boundaries formed as a result of contacting one structure with another, thus, the conduction mechanism is free of extrinsic factors, and can be explained only on the basis of the interactions between the molecular orbitals and the band bending resulting from the charger transfer and creation of an electric field. However, to study isolated materials, contacts on this scale must be carefully prepared and a non-ohmic metal/semiconductor junction must be avoided and, especially, in the case of microfabrication using the dual beam microscope, the contamination with Ga+3 or C/Platinum composite should be minimized. Thus, through this partnership with Prof. Ravi Silva group at the University of Surrey, one seeks the platinum deposition using photo-lithography on specially designed electrodes that allows measuring 2-probe and 4-probe IxV measurements in the same device, in addition to the circuit for self-heating, which together with the use of single nanobelts allows the device to consume only about 10-8W, ideal for use in mobile devices due to its compact size and low power consumption. Besides, Dr. David Cox will be accompanying the candidate in the use of the Dual Beam, improving student skills.The project is intended to be carried out under supervision of both Prof. Marcelo Orlandi and Prof. Ravi Silva. Part of the activities of the master degree project - synthesis; DRX and electron microscopy characterizations; and comparison of the multiple structures (carpet mode) gas sensor response under the self-heating and external-heating modes - was/is taking place in Brazil - and part will be carried out at University of Surrey - devices fabrication (using the photo-lithograph technique) and FIB improvements -, to synergistically combine the expertise and infrastructure of the two groups, thus opening the possibility to achieve transformative results. After the return of the candidate, the gas sensor measurements of the devices fabricated in the UK will be carried out in the LIEC lab (Araraquara-SP/Brazil).
News published in Agência FAPESP Newsletter about the scholarship: