AN INVESTIGATION ON IMPURITY AND GRAIN BOUNDARY EFFECTS ON STRUCTURAL, OPTICAL AND ELECTRICAL PROPERTIES OF SnO2:F THIN FILMS DEPOSITED BY SPRAY PYROLYSIS

We have investigated the effect of fluorine dopant concentration (0-15 F/Sn wt.%) on structural, optical and electrical properties of SnO2 thin films grown by spray pyrolysis technique. According to the experimental evidences and data analysis, we found in these samples: (1) the polycrystalline layers, while in undoped conditions it mainly grow along (211) direction in doped ones (200) is the preferred direction with a direct band gap energy of about 3.7-3.9 eV; (2) The main cause for the relatively high absorption coefficients below E-g could be due to the presence of wide (similar to 1-2 eV) band tails in the forbidden gap; (3) the highest (5.4 x 10(-3) Omega(-1)) figure of merit belongs to the sample with 5 wt.% F/Sn concentration; (4) the grain boundary scattering is the main limiting mechanism in the electrical transport properties of the layers.