Room-temperature spectroscopic ellipsometry data has been analyzed to determine the complex dielectric functions, epsilon(E) - epsilon(1)(E) + i epsilon(2)(E) of as-deposited Sb-doped ZnO (SZO) thin films grown on nSi(100) substrates by dual ion beam sputtering deposition system for different growth temperatures (T-g). The dielectric functions have been obtained from ellipsometry data analyses using Cody-Lorentz oscillator in the GenOsc model. A gradual reduction in the value of electron concentration and finally the conversion of doping characteristics from donor type to acceptor type was observed with the rise in T-g. This, in turn, resulted in the decline of broadening of epsilon(1) peaks, and hence in the increase of excitonic lifetime. Optical band-gap energy was observed to decrease with increase in T-g from 200 to 300 degrees C, and then rise continuously with further increase in T-g. X-ray diffraction measurements showed that all SZO films had (002) preferred crystal orientation. Hall measurement and X-ray photoelectron spectroscopy analysis confirmed that the change in the electrical conduction from n-to p-type was due to the enhancement in the value of Sb-5 vertical bar/Sb-3 vertical bar ratio and Sb-Zn-2V(Zn) complex formation in SZO films. (C) 2015 Elsevier B.V. All rights reserved.