Chemical Bath Co-deposited ZnS Film Prepared from Different Zinc Salts: ZnSO4Zn(CH3COO)2, Zn(NO3)2Zn(CH3COO)2, or ZnSO4Zn(NO3)2

ZnSO4Zn(CH3COO)2, Zn(NO3)2Zn(CH3COO)2, ZnSO4Zn(NO3)2, ZnSO4, Zn(NO3)2 or Zn(CH3COO)2 have been used as zinc sources to prepare ZnS thin films by chemical bath deposition and co-deposition methods. Zn(NO3)2 or/and Zn(CH3COO)2 is/are favorable for cluster by cluster deposition process while ZnSO4 favors ion by ion deposition process regardless of concentration ratios of ZnSO4. However, Zn(NO3)2 affects the nucleation density of ZnS nuclei on the substrate. ZnS thin films deposited from ZnSO4Zn(CH3COO)2 are not only more homogeneous and compact, but also have higher growth rate and adhesion on to the glass substrate. The cubic ZnS films are obtained after only single deposition. The average transmission of films from S6, S7, S8, S9 and S1 for 2 and 2.5 h is greater than 85% in visible region. Compared with the film from S6 (112 nm), the film from S7 is not only thicker (125 nm), but also more transparent. The band gaps of the films deposited from S6, S7, S8, S9 and S1 for 2 and 2.5 h range from 3.88 to 3.98 eV. The effects of anions from different zinc salts are discussed in detail.