The low temperature process design for Al doped ZnO film synthesis on polymer

In order to deposit Al doped ZnO (AZO) films on a polymer substrate, we designed two types of low temperature process with a CFUBM (Closed Field Unbalanced Magnetron) sputtering system. The first one is a reactive magnetron sputtering process using a single ZnO:Al2O3 target. The second is a co-magnetron sputtering system using Al + ZnO targets. In the first process, due to the characteristics of formation of the AZO film in which the presence of Al prevents the ZnO grain growth, a high temperature is needed in order to enlarge the crystallite size. However, in the second process, it is easy not only to synthesize the ZnO film on the polymer due to the low heat of formation of ZnO, but also to control the Al content in the film. In addition, by controlling the hydrogen partial pressure, we obtained highly conductive AZO films with a minimum resistivity of 8 × 10− 4 Ω·cm and a maximum transmittance of 83.2% at a hydrogen partial pressure of 1 mTorr.