Abstract
The present paper reports the effect of Ge addition on the optical band gap and refractive index of thin films. Thin films of and were prepared by thermal evaporation technique at base pressure Pa. Optical band gap and refractive index were calculated by analyzing the transmission spectrum in the spectral range 400–1500 nm. The optical band gap decreases while the refractive index increases with the addition of Ge to . The decrease of optical band gap has been explained on the basis of density of states; and the increase in refractive index has been explained on the basis increase in disorder in the system.
Highlights
Chalcogenide glasses based on the chalcogen elements S, Se, and Te are attractive and widely investigated materials as they possess high optical transparency in the IR region
The As-Se-Ge system has been extensively studied [11,12,13] because of the fact that Ge, As, and Se are the elements of same period in groups IV-VI, and it brings about the covalent character of the interaction between their atoms
The refractive index (n) of the thin films is obtained by the envelope method by making use of the following expressions
Summary
Chalcogenide glasses based on the chalcogen elements S, Se, and Te are attractive and widely investigated materials as they possess high optical transparency in the IR region. They have low phonon energy, high photosensitivity, easy fabrication and processing, and good chemical durability. The As-Se-Ge system has been extensively studied [11,12,13] because of the fact that Ge, As, and Se are the elements of same period in groups IV-VI, and it brings about the covalent character of the interaction between their atoms This results in a broad glass formation region in AsSe-Ge system [14] among all investigated three-component chalcogenide systems
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