Original scientific paper
Structure and optical properties of thin polycrystalline films of CuGaxIn1-xSe2
B. A. Mansour
; Solid State Physics Laboratory, National Research Centre Dokki, Cairo, Egypt
S. A. Abd El-Hady
; Physics Department, Faculty of Science, Helwan University, Cairo, Egypt
A. Abdel-All
; Physics Department, Faculty of Science, Helwan University, Cairo, Egypt
I. K. El Zawawi
; Solid State Physics Laboratory, National Research Centre Dokki, Cairo, Egypt
H. Shaban
; Solid State Physics Laboratory, National Research Centre Dokki, Cairo, Egypt
Abstract
Structural and optical properties of CuGaxIn1−xSe2 (0 ≤ x ≤ 0.75) polycrystalline thin films deposited by vacuum evaporation were studied as a function of composition. The optical absorption spectra of CuGaxIn1−xSe2 thin films (x /=0) show four energy gaps (Eg1 , Eg2 , Eg3 and Eg4 ) which are attributed to the fundamental edge, band splitting by crystal-field and spin-orbit splitting, and to transitions originating from copper 3d levels, respectively. The primary transition energies exhibit bowing behaviour expressed by the relationship Eg1 (x) = 1.011 + 0.448x + 0.186x 2 . The second and third transition energies are higher than the primary transition energies by 0.10–0.11 eV and 0.18–0.185 eV, respectively. The effect of thermal treatment on the values of energy gaps is discussed in terms of the structure of the films. The primary transition energies of annealed CuGaxIn1−xSe2 can be fitted by the parabolic form Eg1 (x) = 1.04 + 0.46x + 0.22x 2 .
Keywords
polycrystalline thin films; CuGaxIn1-xSe2 (0 Ł x Ł 0.75); optical absorption spectra; energy gaps; thermal treatment; fit to primary transition energies
Hrčak ID:
301637
URI
Publication date:
1.5.2003.
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