Comparative study of laser ablation techniques for fabricating nanocrystalline SnO 2 thin films for sensors

Abstract

The microstructure and sensing properties of SnO 2 thin films prepared by using SnO 2 and Sn targets at different substrate temperatures with and without post annealing were investigated systematically. It is found that nanocrystalline SnO 2 films with grain size of 4.0–5.2 nm can be achieved by two methods: (1) by crystallization of amorphous SnO 2 films at 400 °C; and (2) by oxidation of Sn films at 400 °C. The nanocrystalline SnO 2 films prepared with these methods exhibit much higher C 2H 5OH gas sensitivity in comparison with SnO 2 films prepared using SnO 2 and Sn targets at higher substrate temperatures with grain sizes of several tens of nm upon exposure to air containing 2000 ppm C 2H 5OH.