Study and optimization of Al-doped ZnO thin films deposited on PEN substrates by RF-magnetron sputtering from nanopowders targets

Abstract

In this study, we have used RF-magnetron sputtering to deposit Al-doped ZnO (AZO) nanostructures thin films on poly-ethylene naphthalate (PEN) substrates. The compacted AZO nanopowders with different Al concentrations (0, 1, 2, 3 and 4 at.%), which were synthesized by sol–gel method combined with a supercritical drying process, have been used as targets. Structural, optical and electrical properties of deposited thin films with different Al concentrations have been investigated. X-ray diffraction results indicated that all the deposited thin films have hexagonal wurzite structure with c-axis orientation without any secondary phases. The SEM cross section image of the films revealed very dense columnar nanostructure. The best electrical properties (ρ = 4 × 10−4 Ω cm, µ = 22 cm2 V−1 s−1, and ne = 8 × 1020 cm−3) were obtained for the AZO samples containing 2 at.% of Al. The thin films show an average transmittance of 80 % with the PEN substrate in the visible region.