Crystallographic parameters and electro-optical constants in ITO thin films

Abstract

Indium tin oxide thin films were deposited onto soda lime glass substrates using an e-beam evaporation system. In order to improve the structural, electrical and optical properties, the films were annealed at 450 °C and 500 °C in vacuum for 1 h. X-ray diffractions of samples were analyzed by Rietveld refinement and Warren–Averbach methods. By application of Levenberg–Marquardt least square method, the experimental transmittance data were fitted completely with the transmittance data calculated via a combination of modified Drude and Forouhi–Bloomer models. Focusing on the results, it was shown that the samples had a nanosize crystallite and enhancement of the annealing temperature resulted in an increase in the conductivity, carrier concentration, lattice parameter, crystallite size and micro-strain. However, it was found that the defects were preferentially accumulated along grain boundaries in sample annealed at lower temperature. Moreover, the finding revealed that conductivity of the samples was dominated by intra-grain in indium tin oxide films. Furthermore, increasing annealing temperature resulted in the orientation in < 111> crystal texture and also brought in an additional Burstein–Moss shift.