title: Low-Temperature Preparation of Ag-Doped ZnO Nanowire Arrays, DFT Study, and Application to Light-Emitting Diode.
abstract: Doping ZnO nanowires (NWs) by group IB elements is an important challenge for integrating nanostructures into functional devices with better and tuned performances. The growth of Ag-doped ZnO NWs by electrodeposition at 90 °C using a chloride bath and molecular oxygen precursor is reported. Ag acts as an electrocatalyst for the deposition and influences the nucleation and growth of the structures. The silver atomic concentration in the wires is controlled by the additive concentration in the deposition bath and a content up to 3.7 atomic % is reported. XRD analysis shows that the integration of silver enlarges the lattice parameters of ZnO. The optical measurements also show that the direct optical bandgap of ZnO is reduced by silver doping. The bandgap shift and lattice expansion are explained by first principle calculations using the density functional theory (DFT) on the silver impurity integration as an interstitial (Ag(i)) and as a substitute of zinc atom (Ag(Zn)) in the crystal lattice. They notably indicate that Ag(Zn) doping forms an impurity band because of Ag 4d and O 2p orbital interactions, shifting the Fermi level toward the valence band. At least, Ag-doped ZnO vertically aligned nanowire arrays have been epitaxially grown on GaN(001) substrate. The heterostructure has been inserted in a light emitting device. UV-blue light emission has been achieved with a low emission threshold of 5 V and a tunable red-shifted emission spectrum related to the bandgap reduction induced by silver doping of the ZnO emitter material.
authors.affiliation: †Institut de Recherche de Chimie-Paris, CNRS-Chimie ParisTech-PSL, UMR8247, 11 rue Pierre et Marie Curie, 75005 Paris, France.
authors.forename: Thierry
authors.initials: T
authors.lastname: Pauporté
authors.affiliation: †Institut de Recherche de Chimie-Paris, CNRS-Chimie ParisTech-PSL, UMR8247, 11 rue Pierre et Marie Curie, 75005 Paris, France.|‡Department of Microelectronics and Biomedical Engineering, Technical University of Moldova, 168 Stefan cel Mare Boulevard, Chisinau MD-2004, Republic of Moldova.
authors.forename: Oleg
authors.initials: O
authors.lastname: Lupan
authors.affiliation: †Institut de Recherche de Chimie-Paris, CNRS-Chimie ParisTech-PSL, UMR8247, 11 rue Pierre et Marie Curie, 75005 Paris, France.
authors.forename: Jie
authors.initials: J
authors.lastname: Zhang
authors.affiliation: †Institut de Recherche de Chimie-Paris, CNRS-Chimie ParisTech-PSL, UMR8247, 11 rue Pierre et Marie Curie, 75005 Paris, France.
authors.forename: Tugba
authors.initials: T
authors.lastname: Tugsuz
authors.affiliation: †Institut de Recherche de Chimie-Paris, CNRS-Chimie ParisTech-PSL, UMR8247, 11 rue Pierre et Marie Curie, 75005 Paris, France.
authors.forename: Ilaria
authors.initials: I
authors.lastname: Ciofini
authors.affiliation: †Institut de Recherche de Chimie-Paris, CNRS-Chimie ParisTech-PSL, UMR8247, 11 rue Pierre et Marie Curie, 75005 Paris, France.
authors.forename: Frédéric
authors.initials: F
authors.lastname: Labat
authors.affiliation: †Institut de Recherche de Chimie-Paris, CNRS-Chimie ParisTech-PSL, UMR8247, 11 rue Pierre et Marie Curie, 75005 Paris, France.
authors.forename: Bruno
authors.initials: B
authors.lastname: Viana
keywords: Ag-doping; DFT modeling; UV−blue emission; ZnO; electrodeposition; light-emitting diode