Transparent Electrical Conductive Cd-Sn Oxide and Cd-Sn-In Oxide Films

Recently transparent conductive films have been studied in order to find these wide applications on electro-optic devices. The purpose of our study is to obtain cadmium stannate films with high electrical conductivity and high optical transparency in the visible region. The film was prepared on Pyrex glass, quartz and soda-lime glass plate by chemical spray deposition to find an optimum range of substrate temperature. Aqueous solution of cadmium chloride, stannic chloride, and indium chloride was adopted for spray. These films were deposited on a substrate in the range of temperature from 400℃ to 900℃, and high transparent conductive film was obtained, an optimum temperature was found to be in the range from 500℃ to 600℃. Under these conditions, the film prepared from Cd : Sn, 10 : 1 spray solution has a sheet resistance 800 ohms/square, and the film deposited from Cd : Sn, 3 : 1 has a sheet resistance 1200 ohms/square. The optical transmission of Cd-Sn-In films in the visible region depends on the amount of In dopant. The electrical sheet resistance of these films was reduced by heat treatment in O_2 atmosphere for 30-120 minutes at 200℃, and the decrease in sheet resistance during the heat treatment was about 30%. The optical transmission of Cd-Sn film was about 80% in the visible and near-infrared region, and increase in the optical transmission was about 10% by heat treatment for 30 minutes.