Electronic structure, optical, and photoelectrical properties of crystalline Si₂Te₃

• Published in: Semiconductor Physics Quantum Electronics & Optoelectronics
• Date: 2019
• Main Authors: Bletskan, D.I., Vakulchak, V.V., Studenyak, I.P.
• Format: Article
• Language: English
• Published: Інститут фізики напівпровідників імені В.Є. Лашкарьова НАН України 2019
• Subjects: Semiconductor physics
• Online Access: https://nasplib.isofts.kiev.ua/handle/123456789/215501
• Journal Title: Digital Library of Periodicals of National Academy of Sciences of Ukraine
• Cite this: Electronic structure, optical, and photoelectrical properties of crystalline Si₂Te₃ / D.I. Bletskan, V.V. Vakulchak, I.P. Studenyak // Semiconductor Physics Quantum Electronics & Optoelectronics. — 2019. — Т. 22, № 3. — С. 267-276. — Бібліогр.: 40 назв. — англ.

In the framework of the density functional theory (DFT) in the approximation of local density adjusted for the strong correlation (LDA+U method), the band structure, total and partial densities of electronic states, as well as the spatial distribution of the electron density, were calculated. According to the results of the calculation, Si₂Te₃ is an indirect-gap semiconductor with the calculated band gap Eᶜᵃᶥᶜgi = 2.05 eV, close to the experimentally measured Eᵒᵖᵗg = 2.13 eV. The absorption edge and photoconductivity spectra of the Si₂Te₃ crystal within the temperature range 80...293 K has been measured. It has been shown that the dependence of the absorption coefficient on the photon energy is described by the Urbach rule. The parameter σ₀, associated with the constant of electron-phonon interaction, and the energy of effective phonons ħω₍ph₎, involved in the formation of the absorption edge of crystalline Si₂Te₃, were determined using the temperature dependence of the absorption edge slope. Deviation from the stoichiometric composition in the direction of excess tellurium significantly affects the spectral distribution of the photoconductivity of Si₂Te₃ crystals.