Electrical and optical properties of TlInSe₂ single crystals

Abstract

-TlInSe2 is an analog of the TlSe binary compound, it has tetragonal structure with 18 the lattice parameters R = 8.02 % and C = 6.826 % and belongs to the Dqh (14/mcm) space group /I/.Elsewhere /2 to 4/ data were presented on new photoacoustical and piezophotoresistive effects found experimentally with TlInSe2 single crystals. Some photoelectric and optic characteristics of TlInSe2 were studied by other investigat o r s / 5 , 6/.The lack of literature data on the energy structure of TIInSea entailed us to offer this report in which we present the results of experimental investigations on the absorption edge and the temperature dependence of the electric conductivity.TlInSe2 compound was synthesized from thallium and indium monoselenide master alloys. Single crystals were grown by the Bridgman-Stockbarger method.Electrical measurements were carried out in the temperature range from 290 to Ti00 K by the method described in another report /7/, Photoconductivity measurements were carried out by means of an SPM-2-type monochromator (GDR) with a Si02 prism at a slit width of 0.02 to 0.08 mm. The signal was amplified by an YI-2-type amplifier. type spectroyhotometers, a s well a s by means of YM-2-type monochromator. All measurements were carried out at 300 K with the incident radiation perpendicular to the C-axis. The thickness of the specimens varied between 40 and 200 p m . The absorption coefficient ( a~ ) was calculated from transmission and reflection data by the method presented elsewhere /8/.Optical measurements were performed with the use of In the earlier study /1/ a value of 1.12 eV and in another study /2/ a value of 1.2 eV were obtained for the width of the forbidden gap on the basis of the temperature dependence of the conductivity and the Hall effect. Our investigations have shown that in the temperature range from 300 to 480 K the activation energies a r e in good agreement with the published daka. A s the direction of the current in a specimen is changed from that parallel to the crystallographic C-axis to that

Comprehensive DFT investigation of ternary thallium tetragonal crystals: assessing their viability for solar cell applications

“…Note that these results are in agreement with other theoretical findings [4]. Conversely, experimental results indicate that the TlInSe 2 compound has an indirect band gap [11]. This discrepancy in the nature of the band gap indicates a variation between the observed experimental results and the theoretical predictions based on DFT.…”

“…On the experimental side, various techniques have been used to grow thin films of TlInSe 2 [7][8][9][10]. The optical and electrical properties of thallium selenide thin films have been extensively studied using spectroscopy, ellipsometry, and electrical measurements [11][12][13]. Neutron powder diffraction experiments conducted on TlInSe 2 reveal that the tetragonal phase of the crystal remains stable under pressures varied from 0 to 3.3 GPa.…”

Photonic properties of devices based on multicomponent crystalline compounds with content (Si, Ge, Sn)

“…In the experimental side, the optical band gap for TlInSe2 is found to be indirect and reported as ≈ 1.4 eV at room temperature [2]. In another study the indirect band gap is claimed to be 1.2 eV [3]. The indirect and direct band gaps of TlInSe2 are found 1.07 eV and 1.35 eV, respectively in a different study [4].…”

“…Both indirect and direct allowed transitions are observed in TlInSe2 crystals. In [2][3][4][5][6][7] the width of the band gap of crystals was determined by different methods. In the experimental side, the optical band gap for TlInSe2 is found to be indirect and reported as ≈ 1.4 eV at room temperature [2].…”

Phase equilibria in Tl2Se–In2Se3–GeSe2 system at 520 K

“…Ця сполука характеризується вираженою анізотропією фізичних властивостей, зумовленою тим, що носії заряду в ній можуть вільно рухатися всередині шарів (ланцюгів), а між шарами (ланцюгами) їх рух обмежений через ван-дер-ваальсівську взаємодію та мале перекриття хвильових функцій сусідніх шарів (ланцюгів). Для TlInSe 2 вивчено електричні, фотоелектричні властивості, які є ефективними для використання сполуки в дозиметрії рентгенівського діапазону [22,23]. В системі Tl 2 Se-GeSe 2 утворюються три тернарні фази, які відрізняються характером плавлення: Tl 4 GeSe 4 і Tl 2 GeSe 3 плавляться конгруентно при 661 K і 706 K, відповідно, а Tl 2 Ge 2 Se 5 -інконгруентно при 778 K, наявні два евтектичні процеси, які відповідають складам 20 і 35 мол.…”