Transparent and conductive ZnO:Al thin films grown by pulsed magnetron sputtering in current or voltage regulation modes

Aluminium-doped zinc oxide (AZO) thin films have been prepared by pulsed magnetron sputtering from a ceramic oxide target in pure argon atmosphere. Sputtering processes were performed in current or voltage regulation modes at different pulsing frequencies up to 200 kHz. Several growth parameters (discharge power, substrate temperature and growth rate) as well as AZO film properties (crystalline structure, optical transmittance and electrical characteristics) have been measured and analysed as a function of the current or voltage applied, the pulsing frequency and the operation time. By adjusting these deposition parameters, AZO layers with resistivity as low as 1.0×10⁻³ Ωcm and average visible transmittance above 85% have been obtained at growth rate in the range 70-80 nm/min, at substrate temperatures below 150 °C.