Analysis of nanocrystalline coatings of tin oxides on glass by atomic force microscopy

Atomic force microscopy (AFM) was used to study the relation between the surface morphology of SnO2 coatings with their room-temperature resistivities. A hot-plate chemical vapor deposition system fed with vapors of tin tetrachloride and methyl alcohol diluted in a nitrogen gas carrier was used to deposit the SnO2 films on soda-lime glass. It was found that above a critical deposition temperature (T=643 K), the film resistivity reaches its minimum value, which is almost constant over the wide range of the SnCl4 vapor concentration used. AFM revealed that the increase in the deposition temperature increased the grain size and that the surface roughness increases with greater SnCl4 vapor concentration. Therefore films of the same resistivity (deposited at the same temperature) may have different roughnesses.