Conductivity type inversion and optical properties of aluminium doped SnO2 thin films prepared by sol-gel spin coating technique

This paper discuss the structural, optical and electrical properties of aluminium doped tin oxide thin films prepared by sol-gel spin coating technique. The tetragonal rutile structure of SnO2 was confirmed from the XRD measurements and having a preferential orientation along (1 1 0) plane. FESEM analysis reveals that the particles were uniformly distributed in the film and they are in the range of 10.15–39.58 nm. UV-Vis spectroscopy studies shows that the films were highly transparent and the band gap values are ranging from 3.30 to 3.57 eV. FTIR study reveals that the prepared films contain Sn–O–Sn, Sn–O, H–O–H, C–O and Sn–OH vibrations. Hall measurement analysis shows that the conductivity type was reversed from n-type to p-type at higher doping concentration of aluminium. The calculated values of mean free path were ranging from 0.6052 to 5.3732 A0. The Figure Of Merit (FOM) values were calculated and are ranging from 5.58 × 10−7 Ω−1 to 1.74 × 10−5 Ω−1.