Effect of Sb doping on the microstructure and optoelectrical properties of Sb-doped SnO _2 films prepared by spin coating

摘要

Sb-doped SnO _2 (ATO) films were successfully prepared by the spin-coating method starting from colloidal suspensions of ATO nanocrystalline particles. The structural, surface morphological, electrical and optical properties of the films were studied as a function of Sb-doping concentration ranging from 0 to 20% (Sb/(Sb+Sn)). The results indicated that all films were ATO polycrystalline with the typical tetragonal crystal structure of bulk SnO _2. The monotonic decrease of the x-ray diffraction (XRD) peak intensity and the increase of XRD peak width with Sb-doping concentration indicated a finer crystal size distribution and a decrease in crystallization. The films had a porous and netlike microstructure with a more homogeneous and closely packed distribution of nanoclusters when the Sb-doping concentration was increased. The electrical resistivity decreased sharply from 1765 to 0.66Ωcm when the Sb-doping concentration was increased from 0 to 15% and then decreased slightly to 0.52Ωcm when the Sb-doping concentration was increased from 15 to 20%. The film transmittance decreased from 82 to 61% in the visible region. The calculated optical band gap energy first decreased from 4.01 to 3.61eV and then slightly increased to 3.61eV, reaching a minimum value at 15% Sb-doping concentration. The pore/grain contact scattering mechanism of an electron and a photon is presented to explain the novel optoelectrical properties of the films.