Optical, structural and electrical properties of tin doped indium oxide thin films prepared by spray-pyrolysis technique

Tin doped indium oxide (In2O3:Sn) or indium tin oxide (ITO) thin films have been successfully deposited by the low cost spray-pyrolysis method. Low sh eet resistance and high mobility films were obtained when the films were de posited at the substrate temperature of 793 K. The direct optical bandgaps for the films deposited at 793 (a) and 753 K (b) were found to be 3.46 and 3.40 eV, respectively. Similarly, the indirect bandgaps for a- and b-type f ilms were found to be 3.0 and 2.75 eV, respectively. The Burstein-Moss shif t was observed in the films. The refractive index (n) and extinction coeffi cient (k) were found to be in the range of 2.1 to 1.1 and 0.6 to 0.01, resp ectively. The various scattering mechanisms such as lattice, ionized impuri ty, neutral impurity, grain boundary and alloy scattering due to variation of theoretical mobilities with temperature are discussed, in order to compa re experimental results. In the lattice scattering mechanism, the quantum s ize effect phenomena were employed to estimate the energy dilation (E-I). T he a-type films exhibited SnO2 as secondary phase whereas b-type films show ed single phase In2O3:Sn with high sheet resistance. The lattice constants were found to be 10.16 and 10.09 A for a- and b-type films, respectively.