Highly conducting and transparent aluminum-doped zinc oxide films were prepared on quartz and corning glass 7059 substrate by ablating the sintered ZnO target containing 2 wt % Al2O3 with a XeCl excimer laser (λ=308 nm). To grow the films, a repetition rate of 5 Hz and energy density of 1.5 J/cm2 was kept. The effect of substrate temperature from room temperature to 400 °C and oxygen pressure (0.1–5 mTorr) have been investigated by analyzing the optical and electrical properties of these films. The average transmittance was found to be in the range of 86%–92%, and a variable resistivity (ρ) 3.56×10−3–7.0×10−3 Ω cm have been obtained. The lowest resistivity was found to be 1.4×10−4 Ω cm at 300 °C in 1 mTorr of oxygen pressure. Structural changes in the films were also investigated by determining the full width at half maximum of (002) x-ray diffraction peak. These results show improvement in the crystallinity of films, which support our conductivity and transmittance data. The sharp decrease in the transmittance or sharp increase in reflectance near the plasma edge in the near-infrared range has been attributed to impurity scattering, which is Al doping in our films.

p-type conduction in ZnO thin films was realized by the codoping method. Types of conduction and carrier density in codoped ZnO films were found to be dependent on the oxygen partial pressure ratios in the sputtering gas mixture. The lowest room temperature resistivity was found to be 11.77 Ω cm with a hole density of 9.0×1016 cm−3 for the films deposited in 60% of oxygen partial pressure ratio. Codoped films were found to be c-oriented and highly transparent.

The doping mechanism in aluminum doped zinc oxide films has been interpreted by considering the relationship between Hall mobility and effective mass of electrons with carrier concentrations. Both degeneracy and the nonparabolic nature of the conduction band are taken into account for determining the charge state of the dopant. It is ascertained that aluminum liberates one free carrier in the zinc oxide lattice by substituting the zinc atom.

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Undoped and yttrium doped zinc oxide thin films have been deposited on corning glass by dip coating technique. The effect of doping (0–4 wt%) and annealing temperature (300–500 °C) on the structural, optical and electrical properties of the produced films have been investigated. All the films show polycrystalline nature at an annealing temperature of 350 °C. The preferential c‐axis growth with lowest full width at half maximum of (002) reflection peak is seen only up to an optimum annealing temperature. A blue shift in the absorption edge is observed both, with increase in dopant concentration and annealing temperature. The electrical resistivity of the films decreases by doping with yttrium. The lowest resistivity of 3.5 × 10–2 Ω cm and an average transmittance of 86% in the visible range has been obtained in YZO films doped with 3 wt% of yttrium and annealed at 450 °C. (© 2005 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)