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Title: Investigation of structural, electronic, elastic and optical properties of Cd{sub 1-x-y}Zn{sub x}Hg{sub y}Te alloys

Abstract

Structural, optical and electronic properties and elastic constants of Cd1{sub -x-y}Zn{sub x} Hg{sub y}Te alloys have been studied by employing the commercial code Castep based on density functional theory. The generalized gradient approximation and local density approximation were utilized as exchange correlation. Using elastic constants for compounds, bulk modulus, band gap, Fermi energy and Kramers–Kronig relations, dielectric constants and the refractive index have been found through calculations. Apart from these, X-ray measurements revealed elastic constants and Vegard’s law. It is seen that results obtained from theory and experiments are all in agreement.

Authors:
 [1]
  1. Zirve University Faculty of Education, 27260, Gaziantep (Turkey)
Publication Date:
OSTI Identifier:
22611536
Resource Type:
Journal Article
Resource Relation:
Journal Name: AIP Advances; Journal Volume: 6; Journal Issue: 6; Other Information: (c) 2016 Author(s); Country of input: International Atomic Energy Agency (IAEA)
Country of Publication:
United States
Language:
English
Subject:
75 CONDENSED MATTER PHYSICS, SUPERCONDUCTIVITY AND SUPERFLUIDITY; APPROXIMATIONS; CRYSTAL STRUCTURE; DENSITY; DENSITY FUNCTIONAL METHOD; DIELECTRIC MATERIALS; ELASTICITY; ELECTRICAL PROPERTIES; GADOLINIUM COMPOUNDS; KRAMERS-KRONIG CORRELATION; MERCURY COMPOUNDS; OPTICAL PROPERTIES; PERMITTIVITY; QUATERNARY ALLOY SYSTEMS; REFRACTIVE INDEX; TELLURIUM COMPOUNDS; ZINC COMPOUNDS

Citation Formats

Tamer, M., E-mail: mehmet.tamer@zirve.edu.tr. Investigation of structural, electronic, elastic and optical properties of Cd{sub 1-x-y}Zn{sub x}Hg{sub y}Te alloys. United States: N. p., 2016. Web. doi:10.1063/1.4954396.
Tamer, M., E-mail: mehmet.tamer@zirve.edu.tr. Investigation of structural, electronic, elastic and optical properties of Cd{sub 1-x-y}Zn{sub x}Hg{sub y}Te alloys. United States. doi:10.1063/1.4954396.
Tamer, M., E-mail: mehmet.tamer@zirve.edu.tr. Wed . "Investigation of structural, electronic, elastic and optical properties of Cd{sub 1-x-y}Zn{sub x}Hg{sub y}Te alloys". United States. doi:10.1063/1.4954396.
@article{osti_22611536,
title = {Investigation of structural, electronic, elastic and optical properties of Cd{sub 1-x-y}Zn{sub x}Hg{sub y}Te alloys},
author = {Tamer, M., E-mail: mehmet.tamer@zirve.edu.tr},
abstractNote = {Structural, optical and electronic properties and elastic constants of Cd1{sub -x-y}Zn{sub x} Hg{sub y}Te alloys have been studied by employing the commercial code Castep based on density functional theory. The generalized gradient approximation and local density approximation were utilized as exchange correlation. Using elastic constants for compounds, bulk modulus, band gap, Fermi energy and Kramers–Kronig relations, dielectric constants and the refractive index have been found through calculations. Apart from these, X-ray measurements revealed elastic constants and Vegard’s law. It is seen that results obtained from theory and experiments are all in agreement.},
doi = {10.1063/1.4954396},
journal = {AIP Advances},
number = 6,
volume = 6,
place = {United States},
year = {Wed Jun 15 00:00:00 EDT 2016},
month = {Wed Jun 15 00:00:00 EDT 2016}
}
  • The electronic structure of Zn-containing Hg/sub 1-//sub x/Cd/sub x/Te is investigated and the effects of Zn on the band gap and effective masses are estimated. In these studies, ZnTe is treated as an additional alloy constituent and the resulting quaternary alloy Hg/sub 1-//sub x//sub -//sub y/Cd/sub x/Zn/sub y/Te is modeled using both the virtual-crystal approximation and the coherent potential approximation. Numerical results are obtained by utilizing tight-binding band structures of the constituent compounds. Results are presented for the variation of the band gap and electron effective mass with Zn composition y for fixed Cd composition x, and for the dependencemore » of the electron and hole effective masses on Zn composition for two different fixed band gaps in the infrared regime. The results show that Zn-induced alloy disorder effects can be important for determining both the band gap and the effective masses, but that for constant band-gap material the effective masses are almost independent of y.« less
  • The optical, vibrational, structural and elasto-optic properties of quaternary II-VI alloys Zn{sub 0.25}Cd{sub 0.75}S{sub 0.25}Se{sub 0.75}, Zn{sub 0.25}Cd{sub 0.75}S{sub 0.50}Se{sub 0.50} and Zn{sub 0.25}Cd{sub 0.75}S{sub 0.75}Se{sub 0.25} are presented. Within the empirical pseudopotential method (EPM) the disorder effects are modeled via modified virtual crystal approximation (MVCA). The computed bandgaps and the refined form factors are utilized to evaluate optical, vibrational, structural and elasto-optic properties. The refractive index (n), static (ε{sub 0}) and high frequency dielectric (ε{sub ∞}) constants are calculated to reveal optical behavior of alloys. The longitudinal ω{sub LO}(0) and transverse ω{sub TO}(0) optical frequencies are obtained to seemore » vibrational characteristics. Moreover, the elastic constants (c{sub ij}) and bulk moduli (B) are computed by combining the EPM with Harrison bond orbital model. The elasto-optic nature of alloys is examined by computing the photo-elastic constants. These values are significant with regard to the opto-electronic applications especially when no experimental data are available on this system.« less
  • Photoluminescence (PL) spectra and kinetics of narrow gap Hg{sub 1−x}Cd{sub x}Te/Cd{sub y}Hg{sub 1−y}Te quantum well (QW) heterostructures grown by molecular beam epitaxy technique are studied. Interband PL spectra are observed from 18 K up to the room temperature. Time resolved studies reveal an additional PL line with slow kinetics (7 μs at 18 K) related to deep defect states in barrier layers. These states act as traps counteracting carrier injection into QWs. The decay time of PL signal from QW layers is about 5 μs showing that gain can be achieved at wavelengths 10–20 μm by placing such QWs in HgCdTe structures with waveguides.
  • Narrow-gap semiconductors (Hg-,Cd-, and Pb-containing compounds and semimagnetic semiconductors among them) are now attracting investigators` attention. Their effectiveness in applications depends on crystal quality, which is determined by the ways of their production. accordingly, the study of the liquid-phase crystallization conditions is of great importance, as well as the study of features of the component distribution along the ingots, and on the effective coefficients of the component distribution during the crystal growth of the above materials. We grew single crystal of Cd{sub x}Hg{sub 1-x-y}Mn{sub y}Se(Te) solid solutions by the vertical Bridgman technique.
  • A long-wavelength band caused by transitions between states related to the valence band is detected in the photoconductivity spectra of Hg{sub y}Te{sub 1–y}/Cd{sub x}Hg{sub 1–x}Te (CMT) structures with quantum wells. The energy states of mercury vacancies in quantum wells of CMT structures is calculated taking into account a chemical shift. It is shown that the long-wavelength band observed in the photoconductivity spectra of these structures is associated with the ionization of divalent acceptor centers which are such vacancies.