Excitonic and electronic transitions in Me–Sb2Se3 structures

• Published in: Beilstein journal of nanotechnology Vol. 11; no. 1; pp. 1045 - 1053
• Main Authors: Syrbu, Nicolae N, Zalamai, Victor V, Stamov, Ivan G, Beril Stepan I
• Format: Journal Article
• Language: English
• Published: Frankfurt am Main Beilstein-Institut zur Föerderung der Chemischen Wissenschaften 2020; Beilstein-Institut
• Subjects: Anisotropy; Antimony compounds; antimony triselenide; band structure; Brillouin zones; Conduction bands; Crystal lattices; Crystal structure; Electron transitions; Energy bands; Excitons; Full Research Paper; Mathematical analysis; Nanoscience; Nanotechnology; optical spectroscopy; Photoelectric effect; Photoelectricity; reflection and absorption spectra; Selenides; Single crystals; Spectra; Splitting; Symmetry; Temperature; Valence band
• ISSN: 2190-4286; 2190-4286
• DOI: 10.3762/bjnano.11.89

The optical anisotropy of the Sb2Se3 crystals was investigated at 300 and 11 K. Excitonic features of four excitons (A, B, C, and D) were observed in the optical spectra of the Sb2Se3 single crystals and in the photoelectric spectra of the Me–Sb2Se3 structures. The exciton parameters, such as the ground (n = 1) and excited (n = 2) state positions and the binding energy (Ry), were determined. The effective mass of the electrons at the bottom of the conduction band (m c * = 0.67m 0) as well as the holes at the four top valence bands (m v1 * = 3.32m 0, m v2 * = 3.83m 0, m v3 * = 3.23m 0 and m v4 * = 3.23m 0) were calculated in the Г-point of the Brillouin zone. The magnitude of the valence band splitting V1–V2 due to the spin–orbit interaction (Δso = 35 meV) and the crystal field (Δcf = 13 meV) were estimated in the Brillouin zone center. The energy splitting between the bands V3–V4 was 191 meV. The identified features were discussed based on both the theoretically calculated energy band structure and the excitonic band symmetry in the Brillouin zone (k = 0) for crystals with an orthorhombic symmetry (Рnma). The photoelectric properties of the Me–Sb2S3 structures were investigated in the spectral range 1–1.8 eV under E||c and E⟂c polarization conditions and at different applied voltages.