Effect of indium concentration on the structural and electrical properties of Al-doped ZnO thin films grown by pulsed laser deposition

The Al-doped ZnO (AZO) films doped with different indium concentrations were grown on glass substrates (Corning 1737) at 200 0C by pulsed laser deposition. Indium doping in AZO films shows a critical effect on the crystallinity, resistivity and optical properties of the films. The AZO films doped with 0.3 atom% indium content exhibit the highest crystallinity, the lowest resistivity of 4.5 x 10-4 Ω cm and the maximum transmittance of 93%. The crystallinity of the indium doped-AZO films is strongly related to the resistivity of the films. The carrier concentration in the indium doped-AZO films linearly increases with increasing indium concentration. The mobility of the AZO films with increasing indium concentration was reduced with an increase in the carrier concentration and the decrease in mobility was attributed to the ionized impurity scattering mechanism. In optical transmittance, the shift of the optical absorption edge to a shorter wavelength strongly depends on the electronic carrier concentration in the films. The figure of merit FTC used for evaluating transparent electrodes reached 0.32 Ω-1 at 550 nm wavelength.