Influence of ZnO buffer layer thickness on electrical and optical properties of GZO thin films deposited on polymer substrates

Abstract

Ga doped ZnO (GZO) thin films were deposited on polymer polyethylene terephthalate (PET) substrates with a ZnO buffer layer using a radio frequency (RF) magnetron sputtering technique and the effects of the buffer layer thickness on the microstructure, and electrical and optical properties of the GZO films were investigated to develop transparent conductors for flexible display applications. The optimum buffer layer thickness with which the lowest resistivity of the GZO/ZnO films was obtained was determined to be 140 nm. The carrier concentration, the carrier mobility and the electrical resistivity of the GZO film with a ZnO buffer layer 140 nm thick were 7·5 × 10²⁰ cm⁻³, 9·4 cm² V⁻¹ s⁻¹ and 8·8 × 10⁻⁴ Ω cm respectively. The transmittance of the GZO/ZnO films was found to be higher than 85% and nearly independent of the ZnO buffer layer thickness.