Effect of various annealing environments on electrical and optical properties of indium tin oxide on polyethylene napthalate

Abstract

The effect of different annealing ambients on the electrical and optical properties of indium tin oxide (ITO) on polyethylene napthalate (PEN) has been investigated. ITO layers of different carrier concentrations have been prepared by radio frequency sputtering followed by annealing in either 5% H2∕Ar, oxygen, or air at 150°C for 2h. The carrier concentration of the ITO films increased with heat treatment in the 5% H2∕Ar ambient. However, the carrier concentration of the ITO films decreased with heat treatment in oxygen and air atmospheres, respectively. Different annealing ambients affect the electrical properties of ITO/PEN samples by changing the oxygen vacancy in the ITO layer. Electrical mobilities were found to be affected by the carrier concentration. These experimental mobility values were in good agreement with those obtained from a theoretical ionized impurity scattering mechanism model. Optical transmittances of ∼86% were obtained for the ITO thin films and the optical band gap is about 3.15eV for all ITO films on PEN substrates.