Enhanced sensing performance of zinc oxide porous silicon heterojunction-based gas sensors

The structural properties of ZnO and ZnO:Al(2, 4, 6 and 8)%. Nanostructurethin films deposited at 450°C on porous silicon (PS) substrates of p-type and n-type of porous were studied in this work. Thin films preparedvia chemical spray Pyrolysis (CSP)havethickness (150±5 nm). The undoped ZnO and ZnO:Alnanostructure showed the hexagonal wurtzite structure. The structural specifics and microstructure areinvestigatedby X-ray diffraction shows that the excess Aluminum ratio gives raise the crystallite size and lattice constants to be decreasing. Thin films surface morphology drawn from TEM, SEM and AFM analysis exhibit spherical nanoparticles aligned together into a line, and it converted their shape as doping Aluminum used. The thin films sensitivity towards the ethanol and hydrogen gases showed an enhancement proportional to the Al doping ratio, and n-PS substrate has higher sensitivity.