Development of spray technique for the preparation of thin films and characterization of tin oxide transparent conductors

Abstract

Tin oxide (TO) thin films of different thickness have been prepared by a specially designed, fabricated and developed spray technique using a stock solution of alcoholic stannous chloride (0.5 M concentration). The films have been characterized by X-ray diffraction, optical transmission and electrical studies. The XRD patterns show that the films are polycrystalline in nature and the results are in good agreement with ASTM data. From the XRD data ` d' values and grain size of the crystallites have been calculated. The grain size of TO films lie in the range 300–514 Å. Refractive index ( n) and thickness of the films have been determined using optical transmission data. The effect of film thickness on different parameters (figure of merit, conductivity, transmission and refractive index) is presented and discussed. Variation of sheet resistance as a function of film thickness has been discussed. It is observed that the optical and electrical properties of TO films strongly depend on the thickness of the film. Optimum conditions are established based on the maximum figure of merit value. The film prepared at 450°C with the maximum thickness of 5262 Å showed the maximum figure of merit 0.7 × 10 −3 Ω −1. The corresponding film properties are R = 30 Ω per square, T f = 0.70.