Transparent conductive sol-gel thin films for photonic applications

Antimony doped tin dioxide (SnO2:Sb) thin films are fabricated by a new simplified sol-gel process. Films are prepared from an alcoholic solution of SnCl4. 4H(2)O doped with SbCl3. Films are deposited by the spin coating process on sodalime glass, borosilicate glass, silicon wafers and ceramic alumina substrates. The chemical reactions during the heat treatment are monitored by DSC and TG. The chemical composition of the coatings are determined by scanning electron microscopy (SEM). Sheet resistance, R-s, is measured using a linear four-probe technique. Optical properties of the films are also determined. The resistivity of the thin films are presented as a function of the antimony doping level. The smallest sheet resistance of 200 Ohm/square is found for a 250 nm thick coating on a borosilicate substrate. It is observed that the sheet resistance does not decrease linearly with increasing film thickness. Fabrication possibilities of these materials for the integrated optics based sensors including patterning methods are discussed.