ORGANOMETALLIC CHEMICAL VAPOR-DEPOSITION OF SNO2 SINGLE-CRYSTAL AND POLYCRYSTALLINE FILMS

Tin oxide films were deposited by organometallic chemical vapor deposition using tetramethyltin and oxygen as reactants. Possibilities for single crystal growth were investigated by depositing thin films at various growth conditions and on several different orientations of rutile titania and sapphire single crystal substrates. Single crystal films were deposited on titania (110) oriented crystals. The morphology of these films appears practically featureless at 40 kx in a scanning electron microscope. Atomic resolution images of these films were also obtained using atomic force microscopy. Highly textured polycrystalline films were grown on rutile titania (100), (001), and (111) oriented single crystals. X-ray diffraction results show that the orientation of these films follows that of the substrate. Single crystal films having a submicron sized morphology were deposited on sapphire (1102BAR) crystals. Films grown on sapphire (0001) substrates are polycrystalline and show strong (200) or (110) texture depending on the growth conditions. Highly (110) textured films were also deposited on fused quartz substrates at growth temperatures below 475-degrees-C and deposition rates lower than 0.3-mu-m/h. The dependence of film morphology and preferred orientation on substrate and growth conditions is discussed.