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Title: Origin of green luminescence in hydrothermally grown ZnO single crystals

Combining photoluminescence and positron annihilation studies of hydrothermally grown ZnO crystals with stoichiometry varied by controlled annealing enabled us to clarify the origin of green luminescence. It was found that green luminescence in ZnO has multiple origins and consists of a band at 2.3(1) eV due to recombination of electrons of the conduction band by zinc vacancy acceptors coupled with hydrogen and a band at 2.47(2) eV related to oxygen vacancies. The as-grown ZnO crystals contain zinc vacancies associated with hydrogen and exhibit a green luminescence at 2.3(1) eV. Annealing in Zn vapor removed zinc vacancies and introduced oxygen vacancies. This led to disappearance of the green luminescence band at 2.3(1) eV and appearance of a green emission at higher energy of 2.47(2) eV. Moreover, the color of the crystal was changed from colorless to dark red. In contrast, annealing of the as-grown crystal in Cd vapor did not remove zinc vacancies and did not cause any significant change of green luminescence nor change in coloration.
Authors:
; ; ;  [1] ;  [2] ; ;  [3]
  1. Department of Low-Temperature Physics, Charles University in Prague, V Holešovičkách 2, CZ-180 00, Prague 8 (Czech Republic)
  2. Department of Chemical Physics and Optics, Charles University in Prague, Ke Karlovu 3, CZ-121 16, Prague 2 (Czech Republic)
  3. Academy of Science of the Czech Republic, Institute of Physics, Na Slovance 2, CZ-182 21 Praha 8 (Czech Republic)
Publication Date:
OSTI Identifier:
22483086
Resource Type:
Journal Article
Resource Relation:
Journal Name: Applied Physics Letters; Journal Volume: 106; Journal Issue: 25; Other Information: (c) 2015 AIP Publishing LLC; Country of input: International Atomic Energy Agency (IAEA)
Country of Publication:
United States
Language:
English
Subject:
36 MATERIALS SCIENCE; ANNEALING; COLOR; EV RANGE; HYDROGEN; MONOCRYSTALS; OXYGEN; PHOTOLUMINESCENCE; RECOMBINATION; STOICHIOMETRY; VACANCIES; VAPORS; ZINC; ZINC OXIDES