Al-doped zinc oxide films grown by successive chemical solution deposition

Abstract

Films of ZnO were grown and doped by the successive chemical solution deposition technique from a zincate solution containing aluminum (Al/Zn molar ratio in the range 2–10%). To our knowledge, this is the first report of its kind. A post-deposition heat treatment in argon (500 °C, 20 min) was performed for the activation of incorporated Al donors. Films were characterized by using scanning electron microscopy, X-ray diffraction, X-ray photoelectron spectroscopy, optical transmittance, photoluminescence and Hall-effect measurement. Films with a resistivity 0.2 Ω cm, carrier concentration 1.2×10¹⁸ cm^-3 and mobility 26 cm²/V s can be grown from a solution with Al/Zn = 10%. Further reduction in resistivity is plausible by using more heavily doped solutions and by the optimization of annealing parameters. Although the doping process does not change the films’ structure and surface morphology, it slightly lowers the optical transparency in the visible region and blue shifts the room-temperature photoluminescence peak to 378 nm.