Abstract

Introduction. As it is known for today the photosensitive elements on the base of the homoand heterojunctions with using of the semiconductor compounds In₄Se₃, In₄Te₃, and their solid solutions have been obtained by Van der Waals epitaxy method and laser restructuring. These orthorhombic crystals ( D2h12 space symmetry) are isostructural materials and lattice mismatching between constituent materials of heterostructure is equal to 2%. They have the similar band structures; the points of the extremes localizations for both the valence band and conduction band coincide. The In₄Se₃ crystal has the larger energy gap (Eg_exp~0.62-0.8eV) than the In₄Te₃ one (Eg_exp~0.46 eV). Thus, the considered crystals are governed by the favorable parameters for the construction of the heterostructures with the perfect interfaces. The formation of the In₄Se₃/In₄Te₃ heterostructure leads to widening of the spectral sensitivity range of the photoelements. It is established that these elements are sensitive within 1.0-2.0 μm and they are successfully used as infrared detectors and filters.
Purpose. To improve the spectral characteristics of the photosensitive devices it is of interest to study the electronic structure and optical properties of the different type heterostructures on the basis In₄Se₃ and In₄Te₃ materials.
Methods. In this work, we present a first-principles study of the electronic structure and optical properties of the heterostructures on the basis of the In₄Se₃ and In₄Te₃ layered orthorhombic compounds with using of the method of density functional in LDA- approximation.
Results. The band spectra, the spatial distribution of the electron density, the absorption coefficient for different polarizations along crystal axes were calculated.
Conclusion. The evolution of the changes in both energy spectrum and optical functions of the heterostructures in comparison with the In₄Se₃ and In₄Te₃ crystals has been analyzed. It is shown that the increase of the forbidden energy gap and consequently the widening of the of the spectral sensitivity range with the increase of the heterostructure thickness take place. Our calculations suggest a good agreement with experimental investigations. It points on the possibility of the formation of the stable heterostructures of the (In₄Se₃)_m/(In₄Te₃)_m type which can ensured essential photosensitivity in the near and intermedium infrared region

Keywords: heterostructure, indium selenides, electron band structure, spatial distribution of the electron density, dispersive dependence of the absorption coefficient

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