Comparative study of laser ablation techniques for fabricating nanocrystalline SnO2 thin films for sensors

The microstructure and sensing properties of SnO2 thin films prepared by using SnO2 and Sn targets at different substrate temperatures with and without post annealing were investigated systematically. It is found that nanocrystalline SnO2 films with grain size of 4.0-5.2 nm can be achieved by two methods: (1) by crystallization of amorphous SnO2 films at 400 degrees C; and (2) by oxidation of Sn films at 400 degrees C. The nanocrystalline SnO2 films prepared with these methods exhibit much higher C2H5OH gas sensitivity in comparison with SnO2 films prepared using SnO2 and Sn targets at higher substrate temperatures with grain sizes of several tens of nm upon exposure to air containing 2000 ppm C2H5OH.