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S.A.A. Oloomi, A. Saboonchi, A. Sedaghat, Effects of Thin Films’ Number on Nano Scale Radiative Properties, World Applied Sciences Journal 11 (11): 1398-1402, 2010.

World Applied Sciences Journal 11 (11): 1398-1402, 2010


Effects of Thin Films’ Number on Nano Scale Radiative Properties
1S.A.A. Oloomi, 2A. Saboonchi and 2A. Sedaghat
1Department of Material Engineering, Islamic Azad University, Yazd Branch, Yazd, I.R. of Iran
2Department of Mechanical Engineering, Isfahan University of Technology, Isfahan, I.R. of Iran
Many of optical components and semiconductors coated with thin films, so study of thin film coating
is very important for industries. This work uses transfer-matrix method for calculating the radiative properties.
Lightly doped silicon is used and the incoherent formulation is applied. The empirical expressions for the optical
constants of lightly doped silicon are employed. Silicon dioxide and silicon nitride are used as thin film coatings.
It is possible to choose the suitable coating for maximum emittance, minimum transmittance and or minimum
reflectance. It depends on industrial usages. This paper considered effects of thin films’ number with various
compositions of coating materials (9 cases). High emittance is needed for suitable thermal balance of the thinfilm
solar cells for space applications. Optical coatings that provide high emittance must be formed on the solar
cells to overcome that problem by increasing number of thin film layers. Radiative properties are complex
function of wavelength. Increasing number of thin film layers lead to more complexity and dependency on
wavelength regard to wavelength interferences. Results showed that increasing number of thin film coating is
more effective on radiative properties than increasing thickness. For example in the constant total thickness,
it is possible to reach greater emittance by increasing layers’ numbers. From results, the average emittance for
bare silicon from 0.0499 reaches to 0.1725 with coatings in case number 9.
Key words: Thin Films % Number % Different Coatings % Reflectance % Emittance % Transmittance
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