Doping Induced Changes in the Electronic Transitions of Pure and Sn-Doped ZnO Thin Films

Abstract

The un-doped and tin (Sn) doped ZnO films were deposited by spray pyrolysis technique onto glass substrates. 0.1 M solution of zinc acetate in a mixture of ethanol and deionised water. Dopant source was tin chloride SnCl2.2H2O. The atomic percentage of dopant in solution was 2% and 4%. The effect of tin doping on the electronic transitions of ZnO films was studied. The average transmittance values for the films were (76, 84, 88) % for ZnO, ZnO:Sn 2% and ZnO:Sn 4% respectively. The optical band gaps of the films were calculated. The band gap of un-doped sample was 3.36 eV, this value decreased slightly with increasing doping concentration and became 3.17 eV for ZnO:Sn 2% and 3.1eV for ZnO:Sn 4%.