PHYSICAL-PROPERTIES OF PYROLYTICALLY SPRAYED TIN-DOPED INDIUM OXIDE COATINGS

The optical and electrical properties of tin-doped indium oxide coatings obviously depend on a number of production parameters. This dependence has been studied to obtain a more general insight into the relationships between the various coating properties. The coatings have been produced by spray pyrolysis using a solution of indium chloride in butylacetate with tin chloride as a dopant. The influence of the tin concentration, the carrier gas for the spraying, the coating thickness, the substrate temperature and annealing has been investigated using various techniques. The best result is obtained when producing a coating of about 300 nm thickness, using nitrogen as the carrier gas to prevent an excess of oxygen in the coating. When the tin doping is about 5%, the maximum density and mobility of the free electrons are obtained (about 5 x 10(20) cm-3 and 45 cm2 V-1 s-1 respectively). The substrate temperature has to be high; about 580-degrees-C in the case of glass substrates. The electrical and optical properties are satisfactorily described using the theory of ionized impurity scattering. The study of the relation between the structural and the electrical-optical properties shows that the structural properties, i.e. the crystallite size and orientation, influence the electrical and optical properties only weakly.