A study of the optical, electrical and structural properties of reactively sputtered InOx and ITOx films

Films of InOx and ITOx were prepared by DC reactive sputtering from indium and indium-tin alloy targets, respectively, in an oxygen/argon atmosphere. The compositions of the InOx films, determined from EDX, have been used to show how x varies as a function of O-2 partial pressure in the flow to the sputtering system. Reflectance and transmittance of the InOx films and ITOx films were measured in the photon energy range 0.5-6.0 eV, leading to determination of absorption coefficients as a function of x. The optical band gap, which appears as x is increased, was found to increase monotonically with x. The DC resistivity of InOx films has been determined as a function of composition, as have the refractive indices for transparent films and thickness of all InOx and ITOx films. The local structure of InOx and ITOx samples is shown by extended X-ray absorption fine structure to have much configurational disorder throughout the composition range. (C) 1997 Elsevier Science S.A.