Effect of low substrate deposition temperature on the optical and electrical properties of Al₂O₃ doped ZnO films fabricated by ion beam sputter deposition

Aluminum (2 wt %) doped zinc oxide (AZO) films are prepared by ion beam sputtering method on glass substrates with very low substrate deposition temperature below 150 °C. The results of Hall effect measurements showed the decrease in resistivity (2.6×10^-3–7.3×10^-4 Ω cm) came from an increase in mobility and carrier concentration as substrate deposition temperature increased. We confirmed the decrease of resistivity, which resulted from the formation of oxygen deficiency (ZnO_1-x) as substrate deposition temperature increased. The increase of Hall mobility and carrier concentration was also influenced by increases in crystallinity and grain growth of AZO films as substrate deposition temperature increased. The optical transmission of AZO increased from 70% to 80% with increasing substrate deposition temperature. The surface morphology analysis by atomic force microscopy showed the decrease of surface roughness might be related to the development of optical properties. © 2004 American Vacuum Society.