Excimer laser annealing method for achieving low electrical resistivity and high work function in transparent conductive amorphous In2O3:Zn films on a polyethylene terephthalate substrate

Abstract

We have developed an excimer laser annealing method to achieve low electrical resistivity (ρ) and a high work function in amorphous In2O3:Zn (IZO) films on polyethylene terephthalate (PET) substrates. The effect of excimer laser irradiation of the films on crack formation, electrical properties (ρ, carrier concentration, and Hall mobility), and work function were investigated. KrF excimer laser irradiation produced cracks in the surface of the IZO films on PET as a result of thermal expansion of the PET substrate. By inserting an amorphous SiO2 layer as a heat barrier between the IZO layer and PET substrate, crack formation was prevented. Moreover, it was found that the work function of IZO film could be controlled by the laser fluence and repetition rate. Irradiation of a 150-nm-thick amorphous IZO film on a SiO2-coated PET substrate achieved a low ρ of 3.55 × 10−4 Ω cm and a high work function of 5.4 eV due to the reduction of oxygen and carbon while maintaining a flat surface.