ZnO-CoO solid solution thin films

Co-doped ZnO(Zn1-xCoxO) and Co, Al codoped ZnO(Zn1-xCoxO:Al) films were gro wn on c-plane sapphire (0001) substrates by pulsed laser deposition using a KrF excimer laser. In order to enhance homogeneous substitution of Co2+ fo r Zn2+ in the ZnO film, an alternating deposition (AD) method was employed for doping. ZnO films doped with the same elements were grown without emplo ying the AD method under the same fabrication conditions to compare with th e corresponding AD films. Despite Co incorporation, the Zn1-xCoxO film by A D methods showed better crystallinity than pure ZnO film. Also, the crystal linity of Zn1-xCoxO:Al films by AD methods was better than those of Zn1-xCo xO and ZnO:Al films by conventional doping methods. Root mean square roughn esses of the films by AD methods were less than 1.6 nm. Absorption peaks ca used by d-d transitions were observed at 1.88, 2.01, and 2.19 eV in Zn1-xCo xO films. The electric conductivity of Zn1-xCoxO:Al film by AD methods was comparable to that of ZnO:AI film by conventional methods in spite of Co do ping and lower Al concentration. (C) 2001 American Institute of Physics.