Influence of surface defects and preferential orientation in nanostructured Ce-doped SnO2 thin films by nebulizer spray deposition for lowering the LPG sensing temperature to 150 °C

Abstract

Cerium-doped (0.1 to 6 wt.%) nanostructured SnO2 thin films are prepared via nebulizer spray deposition process. The analyses show that the films grow in (301) and (211) preferred orientations. The fabricated sensing films are exposed to LPG at different ppm concentrations and different operating temperatures. In 500 ppm of LPG at an operating temperature of 350 °C, an impressive sensitivity of 89.2 with response time of 7 s and recovery time of 9 s is shown by 2 wt.% Ce-doped film, where the sensitivity is almost 18 times higher than that of pristine SnO2 film. The sensitivities get reduced to 25 at lesser operating temperature of 300 °C and to 1.17 at 150 °C. The films show significant selectivity to CO2, especially at operating temperatures above 300 °C. Raman and photoluminescence studies give an insight into oxygen vacancies and trapped states which influence the enhanced gas response.