Enhanced electrical properties of AZO thin films grown on different substrates by using a facing-target sputtering system with hetero targets

Abstract

Al-doped ZnO (AZO) films were deposited on glass, polyethylene naphthalate (PEN) and polyethylene terephthalate (PET) at room temperature by using conventional rf-magneton sputtering (CMS) and a facing-target sputtering (FTS) with hetero targets of Al₂O₃ and ZnO. Their structural, surface morphology, electrical and optical properties were characterized by using X-ray diffractometry (XRD), atomic force microscopy (AFM), Hall-effect measurement and ultravioletvisible spectrophotometry, respectively. The films exhibit highly c-axis preferred orientation and a closely packed nanocrystalline. Structure the FTS-films deposited on plastic substrate are found to receive much less stress due to bombardment of high-energy particles compress to the CMS-films deposited on plastic substrates, during the sputtering process, which can enhance the electrical properties and crystalline quality of the FTS-films compared with those of the CMS-films. The resistivities of the FTS-films are 6.50 × 10⁻⁴ Ω·cm on glass, 7.0 × 10⁻⁴ Ω·cm on PEN and 7.4 × 10⁻⁴ Ω·cm on PET while the values for the CMS-films are 7.6 × 10⁻⁴ Ω·cm on glass, 1.20 × 10⁻³ Ω·cm on PEN and 1.58 × 10⁻³ Ω·cm on PET.