STUDIES ON METAL-OXIDE SEMICONDUCTOR ZnO AS A HYDROGEN GAS SENSOR

Metal-oxide semiconductor ZnO thin films were prepared on glass slides by spray pyrolysis technique at substrate temperature (410 +/- 10) degrees C. Zn(NO3)(2).6H(2)O was used as the precursor solution. The films thus prepared are undergone for structural and morphological studies using X-ray diffraction and scanning electron microscopy The films are found to be polycrystalline zinc oxide in nature, possessing hexagonal wurtzite crystal structure and nanocrystalline in grain size - 30-35 nm. The hydrogen sensing performance of the films has been investigated for various concentration of hydrogen in air at different operating temperatures in the range 200-400 degrees C. It is observed that the response is maximum (44.3 %) at the operating of temperature of 250 degrees C for 0.8 vol % concentration of hydrogen in air. A possible sensing mechanism for hydrogen has been proposed.