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Title: Electronic band structure of ZnO-rich highly mismatched ZnO{sub 1−x}Te{sub x} alloys

We synthesized ZnO{sub 1−x}Te{sub x} alloys with Te composition x < 0.23 by using pulsed laser deposition. Alloys with x < 0.06 are crystalline with a columnar growth structure while samples with higher Te content are polycrystalline with random grain orientation. Electron microscopy images show a random distribution of Te atoms with no observable clustering. We found that the incorporation of a small concentration of Te (x ∼ 0.003) redshifts the ZnO optical absorption edge by more than 1 eV. The minimum band gap obtained in this work is 1.8 eV for x = 0.23. The optical properties of the alloys are explained by the modification of the valence band of ZnO, due to the anticrossing interactions of the localized Te states with the ZnO valence band extended states. Hence, the observed large band gap reduction is primarily originating from the upward shift of the valence band edge. We show that the optical data can be explained by the band anticrossing model with the localized level of Te located at 0.95 eV above the ZnO valence band and the band anticrossing coupling constant of 1.35 eV. These parameters allow the prediction of the compositional dependence of the band gap as well as the conduction and the valence band offsets in the fullmore » composition range of ZnO{sub 1−x}Te{sub x} alloys.« less
Authors:
;  [1] ;  [2] ;  [3] ;  [1] ;  [2] ;  [4] ;  [1] ;  [5] ;  [1]
  1. Materials Sciences Division, Lawrence Berkeley National Laboratory, Berkeley, California 94720 (United States)
  2. (United States)
  3. National Center for Electron Microscopy, Lawrence Berkeley National Laboratory, Berkeley, California 94720 (United States)
  4. Mechanical Engineering Department, University of California, Berkeley, California 94720 (United States)
  5. (Hong Kong)
Publication Date:
OSTI Identifier:
22412751
Resource Type:
Journal Article
Resource Relation:
Journal Name: Applied Physics Letters; Journal Volume: 106; Journal Issue: 9; Other Information: (c) 2015 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; CONCENTRATION RATIO; COUPLING CONSTANTS; CRYSTAL GROWTH; ELECTRON MICROSCOPY; ELECTRONIC STRUCTURE; ENERGY BEAM DEPOSITION; EV RANGE; GRAIN ORIENTATION; LASER RADIATION; OPTICAL PROPERTIES; POLYCRYSTALS; PULSED IRRADIATION; RED SHIFT; TELLURIDES; VALENCE; ZINC OXIDES