Fabrication of n-ZnO/p-Si++ Hetero-junction Devices for Hydrogen Detection: Effect of Annealing Temperature

In the present study, we report fabrication of n-ZnO/p-Si++ hetero-junction devices for detection hydrogen leakage in ambient air environment. For devices, high quality ZnO thin films are grown by controlled thermal evaporation technique on highly doped p-type silicon substrates at 400 oC. The two sets deposited o C further annealed 500 and 600 oC to examine effect annealing temperature structural, morphological, electrical gas sensing properties films. It is revealed from x-ray diffraction studies that crystallite size, density increase 22.55 24.95 nm, 5.65 5.68 g/cm3, respectively, increasing contrast this, grain boundary specific surface area decreases 8.79 × 107 7.88 m?1 changing responses fabricated have also been recorded different operating temperatures concentrations (200 1000 ppm) ambient. found with up 100 decease beyond this temperature. 400, be 97.22, 64.23 40.77 % respectively ppm hydrogen. A decrease response attributed size (quantum effect), film (i.e. lower penetration) active sites) mechanism these has systematically analyzed under models.