Wrinkle type nanostructured Y-doped ZnO thin films for oxygen gas sensing at lower operating temperature

In the present work, yttrium doped ZnO (YZO) samples with 0, 0.5, 1, 1.5 at. % of Y (coded as YZ-1, YZ-2, YZ-3, YZ-4) were prepared by using sol-gel spin coating technique and investigated for O₂ gas sensing application. The X-ray diffraction pattern revealed that all films have polycrystalline nature with hexagonal wurtzite structure. The size of crystal was varied from 10 nm to 18 nm with increasing the doping level of Y in ZnO. Field-emission scanning electron microscopy (FE-SEM) was used to interpret morphology of thin films and all thin films show wrinkle type morphology at low magnification. The optical bandgap was increased from 3.27 eV to 3.30 eV on increasing the doping level of Y in ZnO. The I–V measurement was recorded by two probe electrometer and it was found that YZ3 has the highest conductivity. The sensor response for YZ4 thin film was observed 1 whereas response and recovery time was 2 s and 4 s, respectively. Based on the literature and to the best of our knowledge, wrinkle type morphology is novel for O₂ gas sensing and no other published work is available in the literature for O₂ gas sensing. The results show Y doped thin films have high potential for oxygen gas sensing at lower operating temperature.