Structural and optical characteristics of transparent conducting yttrium doped ZnO films using screen printing technology

We report on the structural and optical properties of the pure and yttrium(Y) doped zinc oxide (Zn1−xYxO) thick films prepared by screen printing method from their nanopowders. XRD results are well supported by the results obtained from scanning electron microscopy (SEM), photoluminescence, UV–visible spectroscopy and Raman spectroscopy techniques. XRD patterns confirm hexagonal wurtzite structure with single phase of all the samples and SEM micrographs reveal granular grains, dense and porosity in films. The E2 (high) phonon and multiphoton modes are observed at 436 and 333, 1155 cm−1 respectively in Raman spectra. The combination of free and neutral bound excitons near band edge emission with occurance of defects are observed in PL spectra. UV–visible measurement confirms the direct band gap that increases from 3.13 to 3.29 eV. This leads to the increase in strain due to the higher ionic radii of Y3+ ions(0.9 Å) as compared to Zn2+ ions(0.74 Å).