Highly selective H2S sensor realized via the facile synthesis of N-doped ZnO nanocrystalline films

Material and synthesis compatibilities are more crucial to realize integrated sensor systems (lab-on-chip). Zinc oxide (ZnO) is a prospective material for gas-sensing applications because of its remarkable electrical and physical properties, non-toxic nature, and particularly its compatibility with silicon fabrication technology. In this communication, we present the results on the enhanced H 2 S response of nitrogen-doped ZnO (NZO) thin films achieved by controlling the Ar:N 2 ratio during the RF sputtering process. All the films showed vertically oriented nanograins with high crystallinity. XPS studies indicated myriad adsorbed oxygen species for NZO films. Maximum response ( S ) for H 2 S, calculated from the ratio of sensor conductivity after and prior to gas exposure, was obtained at an operating temperature of 300 °C for the films deposited with Ar:N 2 ratio of 2:1 ( S = 45 for 5 ppm of H 2 S). Excess donor defects aided with the large adsorption energy due to nitrogen incorporation conceivably resulted in the enhanced response of NZO for H 2 S.