Growth of Al-doped ZnO thin films by pulsed DC magnetron sputtering

Transparent and conductive Al-doped zinc oxide (AZO) thin films are deposited on glass substrate by pulsed DC magnetron sputtering and the effect of pulse frequency on the structural, electrical and optical properties of the films are investigated. A highly c-axis-oriented AZO thin film is grown perpendicular to the substrate when a pulse frequency of 30 kHz is applied. Under the optimal growth condition, the AZO thin films exhibited the lowest resistivity value of 7.40×10−4 Ω cm and the smoothest surface roughness of Rm=3.25 nm. This indicates that the decreased resistivity of films results from the improvement of crystallinity and surface roughness. The optical transmittance spectra of the films show a very high transmittance of 85-90% in the visible range and exhibit the absorption edge of about 350 nm.