Nanostructuring of SnO2 Thin Films by Associating Glancing Angle Deposition and Sputtering Pressure for Gas Sensing Applications

Abstract

SnO2 thin films were prepared by conventional and Glancing Angle Deposition reactive sputtering, and their gas sensing properties were investigated. The porosity of the as-prepared films was widely assessed using optical methods, and the sensing performances of these active layers were correlated with the evolution of surface and film porosity as a function of deposition conditions and annealing treatment. The sensor made of inclined columns grown at high sputtering pressure (6 ´ 10−3 mbar) and annealed at 500 °C in air exhibited the best response to benzene, with a limit of detection of 30 ppb. In addition, successful BTEX (i.e., benzene, toluene, ethylbenzene, and xylenes) discrimination was achieved by combining the sensing signals of four nanostructured tin-oxide-based gas sensors.

Structure and Void Connectivity in Nanocolumnar Thin Films Grown by Magnetron Sputtering at Oblique Angles

“…These are formed by nanocolumns with a typical diameter and side-to-side distance in the order of 100 nm, making these materials less dense and with a much larger specific surface than their compact counterpart [2][3][4], and with different optical, electrical, and magnetic properties [5][6][7][8][9][10][11][12]. These features make them good candidates for the development of numerous technological devices, such as gas or liquid sensors, optical coatings, and electrodes or instruments for fluid manipulation, among others [13][14][15][16][17][18][19][20][21][22][23][24][25][26]. They are also applied in biomedicine, as the surface energy of the film and its interaction with living organisms can be tuned by modifying the features of the columnar arrangement [27,28].…”