Structural and electrical properties of In2O3:Sn films prepared by radio-frequency sputtering

A series of In23Sn (ITO) films has been prepared by radio-frequency sputtering at 380 degreesC with the oxygen admixture to the sputter gas being varied systematically. At a low oxygen flux, the (400) grains are much larger than grains with other orientations. With increasing oxygen flux, grain diameter and free electron concentration decrease and the texture of the crystallographic orientations changes from (400) to (622) dominant. It is suggested to estimate the fraction of material with a certain orientation by the product of height and third power of the width of the corresponding X-ray peak. This yields the same total X-ray scattering intensity for all samples. The structural properties are explained by a model of dynamic incorporation and segregation of oxygen during film growth. The electron mobility as a function of the electron density roughly follows a power law similar to that of single crystals, indicating that it is dominated by scattering at ionised donors. (C) 2001 Elsevier Science B.V. All rights reserved.