Preparation of Al‐doped ZnO films by aqueous solution process using a continuous circulation reactor

The fabrication of Al‐doped ZnO films by an aqueous solution process using a continuous circulation reactor was studied. By heating ZnO‐saturated ammonia solutions containing 2–10 mM Al(NO3)3 with pH 10.7 at 90 °C under ambient pressure, polycrystalline ZnO films with Al content of 1–2 at.% were deposited. The carrier concentration of ZnO films increased with increasing Al content, indicating that Al was successfully incorporated into the ZnO crystals. The Al‐doped ZnO films had carrier concentrations of 1019–1020 cm−3 and mobilities of 0.7–7 cm2/V/s after annealing at 300 °C in air.