Effect of Doping Behaviors of Ag and S on Formation of p-type Ag-S Co-doped ZnO Film by Modified Hydrothermal Method

Publication date: Available online 5 January 2016
Source:Thin Solid Films
Author(s): Shiwang Long, Yongfeng Li, Bin Yao, Zhanhui Ding, Ying Xu, Gang Yang, Rui Deng, Zhenyu Xiao, Dongxu Zhao, Zhenzhong Zhang, Ligong Zhang, Haifeng Zhao
Reproducible p-type Ag-S co-doped ZnO (ASZO) films were grown on glass substrate by a modified hydrothermal method, where reaction solution is separated from alkali solution and O2is removed from autoclave to avoid deoxidation of Ag⁺ and oxidation of S²⁻ in the solution. It is found that the Ag substitutes for the Zn in monovalent state (AgZn ⁺) and the S for the O in bivalent state (SO ²⁻) in the ASZO. Both AgZn ⁺ and SO ²⁻ have two doping states, one is each AgZn ⁺ is surrounded by 4O²⁻ to form AgZn ⁺ acceptor and eachSO ²⁻ is surrounded by 4Zn²⁺, while the other is one AgZn ⁺ bounds with nSO ²⁻ to form AgZn ⁺-nSO ²⁻(n4) complex acceptor. It is demonstrated that Ag doping can suppress formation of interstitial Zn and O vacancy in the ASZO and S doping can enhance solubility of Ag in the ASZO. Hall measurement indicates that the p-type ASZO film has hole density as high as 10¹⁸ cm⁻³, which is much higher than that of ASZO prepared by magnetron sputtering. The mechanism of formation of the p-type ASZO with high hole density is suggested in the present paper.