Copper ion implantation effects in ZnO film deposited on flexible polymer by DC magnetron sputtering

Abstract

Zinc oxide (ZnO) films were deposited on flexible polyethylene terephthalate (PET) substrates by direct current (DC) magnetron sputtering in ArO2 environment. Singly charged copper ions (Cu+1) of doses 1 × 1011, 1 × 1012, 1 × 1013, and 1 × 1014 ions/cm2 were implanted in ZnO films using Pelletron Accelerator at room temperature. X-ray diffraction revealed c-axis oriented ZnO film having hexagonal wurtzite structure. The crystallite size of ZnO film was decreased with increasing Cu+1 dose up to 1 × 1012 ions/cm2, and then it started increasing with further increase of ion dose. The decrease in crystallite size was attributed to ion-induced lattice disorder in the film whereas the increase in crystallite size at higher doses (>1 × 1012 ions/cm2) was associated with the thermally induced annihilation of defects. The lattice parameter of ZnO was decreased after Cu+1 implantation at different doses that was ascribed to the lower ionic radius of Cu+1 as compared to the Zn+2. The UV–Vis spectroscopic analysis revealed a decrease in band gap of ZnO film after Cu+1 implantation up to 1 × 1013 ions/cm2. However, by increasing ions dose to 1 × 1014 ions/cm2, the band gap was increased. The electrical resistivity of ZnO film was increased at 1 × 1011 ions/cm2 and then decreased with further increase of the dose value.