Highly conductive and transparent aluminum-doped zinc oxide thin films prepared by pulsed laser deposition in oxygen ambient

Abstract

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.