Influence of gamma radiation on the absorption spectra and optical energy gap of Li‐ doped ZnO thin films

Abstract

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 opt g E 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.

Effect of Gamma Irradiation on the Structural and Optical Properties of ZnO Thin Films

“…These two representations are related by [21]: n* = n + ik (7) Ɛ* = Ɛ r + iƐ i (8) Where n, k, Ɛ r and Ɛ i are refractive index (real part), extinction coefficient (imaginary part), real part of dielectric constant and imaginary part of dielectric constant respectively. The extinction coefficient k, describes the absorption of light as it travels through the absorption of light as it travels through the material can be calculated by the following equation [1,22]: Fig. (7) shows decrease of extinction coefficient with increasing wavelength for the films, and values of for unirradiated is less than that irradiated.…”

“…(7) shows decrease of extinction coefficient with increasing wavelength for the films, and values of for unirradiated is less than that irradiated. The refraction index, real part and imaginary part of dielectric constants were calculated from the following equations [1,22]:…”

“…In the normal dispersion region the dispersion of refractive index has been analyzed using the single oscillator model which is analyzed according to the single -effective -oscillator model proposed by Wemple and Di Domenico [22][23][24][25].…”

ZnO films fabricated by spin coating and their application to UV electroluminescent devices

“…At present, we are attempting to measure their spectra. 4 Discussion We assume that the absorption coefficient of ZnO films for the excitation source is 5x10 4 cm -1 [3] and the relaxation energy (E exc -E g ), the absorbed energy, which comes from the excitation light, is 730 µW. The estimated output power of the PL is 8.8 µW.…”

Effects of gamma irradiation on hydrogen gas-sensing characteristics of Pd–SnO2 thin film sensors

“…Gamma irradiation has been reported to significantly affect the structure and optical properties of metal oxides [17,18]. Gamma irradiation was also reported to affect the electrical properties of various materials and devices [19,20].…”