Origin of green luminescence in hydrothermally grown ZnO single crystals
- Department of Low-Temperature Physics, Charles University in Prague, V Holešovičkách 2, CZ-180 00, Prague 8 (Czech Republic)
- Department of Chemical Physics and Optics, Charles University in Prague, Ke Karlovu 3, CZ-121 16, Prague 2 (Czech Republic)
- Academy of Science of the Czech Republic, Institute of Physics, Na Slovance 2, CZ-182 21 Praha 8 (Czech Republic)
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.
- OSTI ID:
- 22483086
- Journal Information:
- Applied Physics Letters, Vol. 106, Issue 25; Other Information: (c) 2015 AIP Publishing LLC; Country of input: International Atomic Energy Agency (IAEA); ISSN 0003-6951
- Country of Publication:
- United States
- Language:
- English
Similar Records
ZnO Luminescence and scintillation studied via photoexcitation, X-ray excitation and gamma-induced positron spectroscopy
Formation of high concentrations of isolated Zn vacancies and evidence for their acceptor levels in ZnO