Comparison of RF and pulsed magnetron sputtering for the deposition of AZO thin films on PET

AZO thin films (around 200 nm thick) were grown on polyethylene terephthalate (PET) at room temperature. The plasma was activated using a 13.56 MHz (RF) or a 15 kHz pulsed (PMS) source at a power of 60 W. Optical reflection and transmittance were measured using a UV-Vis-NIR spectrometer over the wavelengths from 190 nm to 2500 nm. All samples show average transmittances greater than 83% in the visible region. The electrical resistivity was measured by the linear four-point probe method to be around 0.001 Ωcm for 200 nm-thick AZO films grown by PMS. XRD results indicated that the films had a hexagonal wurtzite structure and were preferentially oriented in the (002) plane. The surface morphology of the AZO thin films was characterized using Scanning Electron Microscopy (SEM); film chemical composition was studied using Energy Dispersive X-ray Spectroscopy (EDS). For this, an EDS coupled to the Scanning Electron Microscope was used. Only for films grown by PMS were no cracks observed. (author)