Mechanism of Ag Doping in ZnO Nanowires by Electrodeposition: Experimental and Theoretical Insights

• Published in: Journal of physical chemistry. C 2012-03, Vol.116 (10), p.6383-6391
• Main Authors: Thomas, M. A, Sun, W. W, Cui, J. B
• Format: Article
• Language: English
• Subjects: Cross-disciplinary physics: materials science; rheology; Electrodeposition, electroplating; Exact sciences and technology; Materials science; Methods of deposition of films and coatings; film growth and epitaxy; Methods of nanofabrication; Nanoscale materials and structures: fabrication and characterization; Other topics in nanoscale materials and structures; Physics; Quantum wires
• ISSN: 1932-7447; 1932-7455
• DOI: 10.1021/jp2107457

A range of complementary techniques was used to explore the physical mechanisms of Ag doping in ZnO nanowires obtained by a low-temperature electrochemical process. Cyclic voltammetry analysis was employed to demonstrate the ability of Ag to modify the electrochemistry and in turn the ZnO growth environment generating amenable conditions for p-type doping. Both X-ray photoelectron spectroscopy and calculations using density functional theory (DFT) showcase that the principal Ag impurity in the nanowires is Ag substitution for Zn (AgZn). The calculations also indicate that AgZn doping forms an impurity band because of Ag 4d and O 2p orbital interactions shifting the Fermi level toward the valence band. Electrical characterization of the Ag-doped nanowires confirms the observations in the DFT calculations. It was also found that the formation of Ag acceptors is favorable under O rich growth conditions which can be experimentally tuned. The combination of experimental and theoretical studies performed in this work helps us to understand the Ag-doping mechanism in low-temperature growth opening up possible directions toward highly conductive p-type ZnO for advanced optoelectronic applications.