GROWTH AND CHARACTERIZATION OF TIN OXIDE-FILMS PREPARED BY CHEMICAL VAPOR-DEPOSITION

Undoped tin oxide films have been prepared by a chemical vapour deposition technique. The effect of different deposition parameters on the sheet resistance of the films has been studied. Films are highly transparent (about 90%) in the visible region, have a quite low sheet resistance (25 Ω/□) and have reproducible properties. X-ray diffraction shows the structure to be polycrystalline with a grain size of about 570 Å. The preferred orientation is (101) for the films deposited at substrate temperatures up to 350 °C, after which the preferred orientation changes to (200). The electrical properties of the films also exhibit a change at this deposition temperature. Direct and indirect band gaps are calculated to be 3.93 eV and 2.53 eV respectively. Degradation of the films with time has also been studied. The figure of merit φ{symbol} = T10/Rsh (9.45 × 10-3Ω-1 at 0.66 μm) obtained is the highest amongst the values reported for undoped tin oxide films. © 1990.