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Title: Interplay of Cu and oxygen vacancy in optical transitions and screening of excitons in ZnO:Cu films

We study room temperature optics and electronic structures of ZnO:Cu films as a function of Cu concentration using a combination of spectroscopic ellipsometry, photoluminescence, and ultraviolet-visible absorption spectroscopy. Mid-gap optical states, interband transitions, and excitons are observed and distinguishable. We argue that the mid-gap states are originated from interactions of Cu and oxygen vacancy (Vo). They are located below conduction band (Zn4s) and above valence band (O2p) promoting strong green emission and narrowing optical band gap. Excitonic states are screened and its intensities decrease upon Cu doping. Our results show the importance of Cu and Vo driving the electronic structures and optical transitions in ZnO:Cu films.
Authors:
;  [1] ;  [2] ;  [2] ;  [3] ;  [1] ;  [2] ; ;  [4] ;  [5]
  1. Singapore Synchrotron Light Source, National University of Singapore, 5 Research Link, Singapore 117603 (Singapore)
  2. (Singapore)
  3. (Indonesia)
  4. Department of Physics, Institut Teknologi Bandung, Ganesa 10, Bandung 40132 (Indonesia)
  5. Department of Material Science and Engineering, National University of Singapore, 7 Engineering Drive 1, Singapore 117574 (Singapore)
Publication Date:
OSTI Identifier:
22293033
Resource Type:
Journal Article
Resource Relation:
Journal Name: Applied Physics Letters; Journal Volume: 104; Journal Issue: 8; 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; ABSORPTION SPECTROSCOPY; CONCENTRATION RATIO; COPPER; CRYSTAL DOPING; ELECTRONIC STRUCTURE; ELLIPSOMETRY; ENERGY-LEVEL TRANSITIONS; EXCITONS; OPTICS; OXYGEN; PHOTOLUMINESCENCE; TEMPERATURE RANGE 0273-0400 K; THIN FILMS; ULTRAVIOLET RADIATION; VACANCIES; ZINC OXIDES