Comparative studies of Al-doped ZnO and Ga-doped ZnO transparent conducting oxide thin films

We have investigated the influences of aluminum and gallium dopants (0 to 2.0 mol%) on zinc oxide (ZnO) thin films regarding crystallization and electrical and optical properties for application in transparent conducting oxide devices. Al- and Ga-doped ZnO thin films were deposited on glass substrates (corning 1737) by sol-gel spin-coating process. As a starting material, AlCl(3)a <...6H(2)O, Ga(NO3)(2), and Zn(CH3COO)(2)a <...2H(2)O were used. A lowest sheet resistance of 3.3 x 10(3) abroken vertical bar/a- was obtained for the GZO thin film doped with 1.5 mol% of Ga after post-annealing at 650A degrees C for 60 min in air. All the films showed more than 85% transparency in the visible region. We have studied the structural and microstructural properties as a function of Al and Ga concentrations through X-ray diffraction and scanning electron microscopy analysis. In addition, the optical bandgap and photoluminescence were estimated.