Structural, morphological, electrical and optical studies of Cr doped SnO2 thin films deposited by the spray pyrolysis technique

Tin oxide (SnO2) and chromium (Cr) doped tin oxide (Cr:SnO2) thin films were deposited on the preheated glass substrates at 673 K by spray pyrolysis. Concentration of Cr was varied in the solution by adding chromium (III) chloride hexahydrate from 0 to 3 at%. The effect of Cr doping on the structural, electrical and optical properties of tin oxide films is reported. X-ray diffraction pattern confirms the tetragonal crystal structure for undoped and Cr doped tin oxide films. Scanning electron microscopic photographs show the modification of surface morphology of tin oxide film due to varying concentration of Cr. X-ray photoelectron spectra of Cr:SnO2 (3 at%) thin film revealed the presence of carbon, tin, oxygen, and chromium. Carrier concentration and mobility of the SnO2 films decrease with increasing concentration of Cr and 0.5 at% Cr doped tin oxide film acquires a mobility of 70 cm2/V s. Average optical transmittance in the 550–850 nm range varies from 38% to 47% with varying Cr concentration in the solution.