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Title: Structural, optical, and magnetic properties of (Co, Cu)-codoped ZnO films with different Co concentrations

Zn{sub 0.99-x}Co{sub x}Cu{sub 0.01}O films with different Co concentrations from 0% to 20% were fabricated by a sol-gel method. Moderate Co doping is found to improve the surface uniformity and crystal quality of the films, and causes a redshift of the band edge of Zn(Co,Cu) films. X-ray photoelectron spectroscopy reveals that the introduction of Co ions causes the valence state of Cu to change from +2 to +1; while at Co concentrations lower than 10%, the Co exists in the +2 valence state. Strong blue emission at ∼420 and 440 nm are observed, decreasing with increasing Co concentration, but becoming strong again as the concentration is increased to 20%. Enhanced room-temperature ferromagnetism is observed for the (Co, Cu)-codoped ZnO films at Co concentrations lower than 10%. These interesting magnetic properties are explained based on charge transfer, together with the defect-related model for ferromagnetism.
Authors:
; ; ;  [1] ;  [2] ;  [3]
  1. Key Lab of Information Materials of Sichuan Province and School of Electrical and Information Engineering, Southwest University for Nationalities, Chengdu 610041 (China)
  2. National Laboratory of Solid State Microstructures and Department of Physics, Nanjing University, Nanjing 210093 (China)
  3. Institute of Solid State Physics, Sichuan Normal University, Chengdu 610068 (China)
Publication Date:
OSTI Identifier:
22277945
Resource Type:
Journal Article
Resource Relation:
Journal Name: Journal of Applied Physics; Journal Volume: 115; Journal Issue: 9; Other Information: (c) 2014 AIP Publishing LLC; Country of input: International Atomic Energy Agency (IAEA)
Country of Publication:
United States
Language:
English
Subject:
75 CONDENSED MATTER PHYSICS, SUPERCONDUCTIVITY AND SUPERFLUIDITY; COBALT COMPOUNDS; COBALT IONS; CONCENTRATION RATIO; COPPER COMPOUNDS; CRYSTALS; FERROMAGNETISM; MAGNETIC PROPERTIES; RED SHIFT; SOL-GEL PROCESS; TEMPERATURE RANGE 0273-0400 K; THIN FILMS; VALENCE; X-RAY PHOTOELECTRON SPECTROSCOPY; ZINC OXIDES