A novel method for preparing stoichiometric SnO2 thin films at low temperature

Tin oxide is a well known nonstoichiometric material with dual valency. The invariance of stoichiometry is very intriguing. As of today no report is available for preparing perfect stoichiometric tin oxide. Here we report a novel method to prepare stoichiometric tin oxide by modifying the known plasma enhanced chemical vapor deposition technique using SnCl(4)-xH(2)O as precursor and O(2) as reactant gas at various temperatures from 300 to 800 degrees C. Tetragonal rutile structure of SnO(2) was found, grown along the [110] direction. X-ray photoelectron spectroscopic measurement showed constant Sn/O ratio. Sn 3d and O 1s were found composed of only Sn(4+) (487.2 eV) and O-Sn(4+) (531.2 eV) with equal peak widths. Raman band intensity ( approximately 633 cm(-1)) was found increasing with temperature, indicating the morphological changes. Sheet resistance of approximately 0.5 kOmega/at 300 degrees C was measured that reduces to approximately 0.1 kOmega/at 600 degrees C. It is found that film stoichiometry remains unaltered, while the structural morphology changes significantly.