Enhancement of LPG sensing properties in nanocrystalline zinc oxide thin film by high electronic excitation

Abstract

We present an efficient detection of liquefied petroleum gas (LPG) using zinc oxide (ZnO) thin films irradiated with swift heavy ions (SHI) of 120 MeV Au 9+ ions. The nanostructured ZnO thin films on ITO glass substrates were synthesized using a simple, low cost, and efficient successive ionic layer adsorption and reaction (SILAR) technique. The as-synthesized thin films were annealed at 250 °C (pristine) in vacuum atmosphere (10 −2 Torr) for 1 h and these films were further irradiated using SHI of 120 MeV Au 9+ ions with different fluence 3 × 10 12 and 5 × 10 12 ions/cm 2, respectively. SHI induced modification in structural, morphological, optical and electrical properties of ZnO thin films were studied. We observed significant enhancement in LPG gas sensing properties in the ZnO thin films on irradiation with fluence 5 × 10 12 ions/cm 2, especially showing maximum sensitivity to LPG at (200 °C) with LPG concentration of 200 ppm. In addition, irradiated ZnO thin film sensors displayed fast response and recovery time. The observed improvement in gas sensing properties is mainly attributed to the formation of cabbage leaf-like porous ZnO nanostructures throughout the film surface after irradiation. These results along with a simple fabrication process demonstrate that the ZnO thin films irradiated using 120 MeV Au 9+ ions with fluence 5 × 10 12 ions/cm 2 is promising for developing low cost and high performance LPG sensors.