Sensing characteristics of epitaxially-grown tin oxide gas sensor on sapphire substrate

Epitaxial SnO2 film was grown on a sapphire substrate using a reactive rf m agnetron sputter. The microstructure of the thin film was investigated usin g the 3C(2) beam line from a Pohang Light Source (PLS) consisting of a 2 Ge V electron accelerator, four circle X-ray diffractometer, atomic force micr oscopy (AFM), and transmission electron microscopy (TEM) comparing with the SnO2 film on the polished alumina. It was confirmed that the thin film gre w epitaxially on the sapphire substrate with a variant crystal structure [D evelopment of microstructure controlled and ultrathin SnO2 gas sensing film , in: Proceedings of the 5th International Meeting on Chemical Sensors, Rom e. Italy, 1994]. No grain boundary was exhibited on the surface of the epit axial thin film. A large portion of the sorption sites in SnO2 films appear s to react easily with the gas. An epitaxial SnO2 gas sensor, with a Pt heater and electrodes, exhibited a high sensitivity to combustible gases and a particular sensitivity of 95% t o alcohol at 2000 ppm and 350 degreesC. The sensor also showed a good stabi lity with small baseline drift and fast reaction and recovery times of abou t 5 and 30 s, respectively. This experiment confirms the good gas-sensing characteristics of an epitaxi ally-grown SnO2 gas sensor. (C) 2001 Elsevier Science B.V. All rights reser ved.