Perchlorate-Induced Doping of Electrodeposited ZnO Films for Optoelectronic Applications

The aim of this work is to produce via a low cost technique a thin film of ZnO showing optoelectronics properties similar to those one could obtain through various vacuum techniques. In order to achieve such goal, electrodeposition appears to be one of the most interesting approaches. Employing such technique in a Cl-containing bath, a high doping of the ZnO layer can be readily achieved through the substitution of a chloride ion for an oxygen atom in the ZnO lattice: the Obtained optoelectronic properties are comparable to the ones of vacuum deposited layer. However, the introduction of chloride was found to be difficult to control, leading to a high concentration of inactive chloride in the ZnO lattice and, as a result, lower electrical performances, of the material. In this study; the limitation of chloride doping is evidenced and explained considering the formation of chloride rich compounds. Moreover, ab initio calculations demonstrate that incorporation of perchlorate ions in the ZnO lattice at an oxygen site is possible and highlight the efficient doping character of this substitution. Then the influence of the perchlorate ions on the morphological, structural, and optoelectronic properties of electrodeposited ZnO thin films have been experimentally explored. In particular, this study demonstrates that the use of perchlorate as chlorine source prevents the formation of undesirable chlorine rich phases and to reach high doping level and mobility up to 1.7 x 10(20) cm(-3) and 19 cm(2).V-1.s(-1), respectively.