Structural, optical, and electrical properties of AZO films by tilted angle sputtering method

We investigate the structural, optical, and electrical properties of aluminum-doped zinc oxide (AZO) films on Si substrate by a tilted angle sputtering method. The substrate holder is tilted by varying the angle from theta(sh)=0 degrees to theta(sh)=80 degrees during the sputtering process. As the tilted angle is increased, the deposition rate is increased due to the decreased distance between the substrate and the target. Without substrate rotation, the deposited AZO films exhibit apparently the inclined nanocolumnar structures, depending on the tilted angle. The refractive index, which is related to the porosity within films, is reduced for the larger inclined nanocolumnar structure while the extinction coefficient remains almost the same in the visible wavelength range. The inclination of nanocolumns disappears when the substrate is rotated. On glass substrate, the electrical properties as well as optical transmittance of AZO films are also dependant on the tilted angle. (c) 2010 Elsevier B.V. All rights reserved.