CZTS thin films are deposited by RF sputtering on MO coated glass substrate. UV absorbance of these thin films shows multiple fringes/peaks.
Due to analyze properties of CZTS (Cu2ZnSnS4) films coated on opaque substrates, the process conditions are often optimized on normal soda lime glass substrates and then transfer the process to Mo coated soda lime glass (SLG) substrates for device fabrication. This study concentrates on the analysis of structural properties of CZTS films on normal glass and Mo coated SLG substrates. CZTS films were coated on these two substrates by spin coating followed by sulphurization in N2 + H2S atmosphere. Phase purity of the films was analyzed by GIXRD and Raman spectroscopy. W–H analysis was used for estimating crystallite size and lattice strain of the films on the two substrates. Detailed structural studies were carried out with Rietveld refinement technique using GSAS package. Kesterite model with space group I4 (SG No: 82) was chosen for the refinement. Formation of kesterite phase on both substrates was confirmed from the refined lattice constant values. Deviation in bond angle with respect to kesterite structure was also analyzed. Different structural parameters were observed for the films on these substrates. The study indicates that it is important to optimize the properties of CZTS film on Mo coated SLG substrate separately, without following the same preparation conditions used for coating film on glass substrates.
The reason behind the fringes is that light has wave properties and the forward travelling light wave interferes with backward travelling waves that are reflected at substrate surface. See e.g. Article Removing interference-based effects from infrared spectra - ...
Interference fringes are damped in the absorbing part of the spectrum and alter intensities in these region. A simple background correction does not help!
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