Green photoluminescence and photoconductivity from screen-printed Mg doped ZnO films

Dominant green emission, more than five times stronger than the accompanying UV emission, is obtained from screen printed ZnO films with 15 at%Mg doping, although no such emission was present in the starting oxide powders. Photoexcitation was done by 325 nm radiation obtained from xenon discharge lamp. Photoresponse to 365 nm illumination is studied and photosensitivity gets enhanced by nearly three times by doping. All the films; undoped and doped; are polycrystalline with hexagonal wurtzite structure and predominant orientation along (101) plane. Crystallite size lies between 60 and 146 nm. Absorption peak shifts from 379 to 371 nm with successive increase in doping indicating an increase in band gap of the film. Surface structure consists of microclusters of dodecahedron-type and nearly spherical grains reducing in size with doping. EDX confirms the presence of Zn, O and Mg.