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Influence of gamma radiation on the absorption spectra and optical energy gap of Li‐ doped ZnO thin films
Author(s) -
Abu ElFadl A.,
ElMaghraby E. M.,
Mohamad G. A.
Publication year - 2004
Publication title -
crystal research and technology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.377
H-Index - 64
eISSN - 1521-4079
pISSN - 0232-1300
DOI - 10.1002/crat.200310162
Subject(s) - attenuation coefficient , absorption edge , photon energy , absorption (acoustics) , band gap , sapphire , thin film , doping , materials science , irradiation , analytical chemistry (journal) , absorption spectroscopy , extended x ray absorption fine structure , spectral line , two photon absorption , optics , molecular physics , chemistry , photon , optoelectronics , laser , nanotechnology , physics , chromatography , astronomy , nuclear physics , composite material
We have studied the effect of subsequent gamma (γ) irradiation on the absorption spectra and the optical energy gap of ZnO thin films doped with Li (ZnO:Li). The optical transmission (T) and optical reflection (R) in the wavelength range 190∼800 nm of films deposited at 300 °C on sapphire, MgO or quartz substrates were measured. The dependence of the absorption coefficient α on photon energy hν was determined as a function of γ‐doses. The films show direct allowed interband transition that influenced by the gamma doses. Both the optical energy gap E opt g and the absorption coefficient (α) were found to be γ‐dose dependent. The results can be discussed on the basis of γ‐irradiation‐induced defects in the film and on the film structure. The absorption coefficient exhibits exponential dependence on photon energy obeying Urbach's rule in the absorption edge. (© 2004 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)