Elaboration of tin oxide nano-islands through post-deposition thermal treatment

Abstract : Tin dioxide (SnO2) films have been grown onto (006) sapphire substrates by sol-gel dip-coating using tin alkoxide solutions. It is shown, using transmission electron microscopy and atomic force microscopy, that the thickness of the layers is easily controlled with tin concentration. It can vary after the deposition process between few nanometers and few tens of nanometers according to the concentration of the precursor in the sol. A postdeposition thermal treatment forces the continuous precursor film to split into isolated islands. A decrease of the tin concentration in the precursor sol to 100 μM allows the formation of islands of a few nanometers (3 nm) in height and several tens of nanometers in diameter (30 nm). Such height value is very close to the Bohr radius of SnO2.