Band structure, electronic and optical features of Tl4SnX3 (X = S, Te) ternary compounds for optoelectronic applications

• Published in: Journal of alloys and compounds 2017-07, Vol.710, p.600-607
• Main Authors: Piasecki, M., Brik, M.G., Barchiy, I.E., Ozga, K., Kityk, I.V., El-Naggar, A.M., Albassam, A.A., Malakhovskaya, T.A., Lakshminarayana, G.
• Format: Article
• Language: English
• Subjects: Anisotropy; Band structure; Band structure of solids; Carrier density; Carrier mobility; Charge density; Crystal growth; Current carriers; Density; Density distribution; Density functional theory (DFT); Dielectrics; Electron charge distribution; Electronic band structure; Electronics; Optical properties; Optical reflection; Optoelectronics; Reflectance; Single crystals; Space charge; Surface energy (anisotropy)
• ISSN: 0925-8388; 1873-4669
• DOI: 10.1016/j.jallcom.2017.03.280

In the present work, details of the crystal growth (Bridgeman method) and optical reflection spectroscopy for two single crystals (X = S, Te) were reported. Detailed ab-initio DFT calculations of the structural, electronic and optical properties of the crystals were performed for a deeper understanding of the experimentally obtained optical data. The special attention is paid to the electron charge density distribution, carrier mobility, optical reflectivity spectra and finally the anisotropy of the corresponding optical functions were studied. Were established a relations with carrier mobility, the optical anisotropy and electronic band structures for the titled crystals and compared with the optical reflectance spectra, covering the range of principal inter-band transitions. The origin of the calculated bands and effects of the anion substitution (Se by Te) on the crystal properties are studied. The role of screening effects is discussed by a comparison of the GGA and LDA approaches, including the electronic band dispersion and effective masses anisotropy. The possible changes of the inter-band transition are considered. The relation between the space charge density distribution and optical features is established. Finally was explained the origin of the observed discrepancies between the experimental and theoretical data. [Display omitted] •We report crystal growth and reflection spectroscopy for crystals Tl4SnX3 (X = S, Te).•DFT calculations of the structural, electronic and optical analysis were performed.•The effect of the anion substitution (Se by Te) on the crystal properties is studied.•Influence of the space charge density distribution on optical features is established.