Search query: Optical and electronic properties of some semiconductors from energy gaps

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abstract: Abstract II VI and III V tetrahedral semiconductors have significant potential for novel optoelectronic applications. In the present work, some of the optical and electronic properties of these groups of semiconductors have been studied using a recently proposed empirical relationship for refractive index from energy gap. The calculated values of these properties are also compared with those calculated from some well known relationships. From an analysis of the calculated electronic polarisability of these tetrahedral binary semiconductors from different formulations, we have proposed an empirical relation for its calculation. The predicted values of electronic polarisability of these semiconductors agree fairly well with the known values over a wide range of energy gap. The proposed empirical relation has also been used to calculate the electronic polarisability of some ternary compounds.
author_names: Sunil Kumar Tripathy

Anup Pattanaik
title: Optical and electronic properties of some semiconductors from energy gaps
year: 2016

abstract: The structural, electronic and optical properties of the Li2In2XY6 (X Si, Ge; Y S, Se) compounds, which are scarcely studied by theoretical methods previously, have been investigated by ab initio calculations based on the density functional theory (DFT) in this article by using the full potential linearized augmented plane wave method. The equilibrium structural ground state properties of the Li2In2XY6 (X Si, Ge; Y S, Se) compounds such as the lattice parameters were obtained from the structural optimization process (with the Perdew Burke Ernzerhof generalized gradient approximation) and they are in close agreement with the experimental lattice parameters. Conversely, calculations by the modified Becke Johnson exchange potential indicates that the Li2In2XY6 (X Si, Ge; Y S, Se) compounds are semiconductors with direct energy band gaps. It is clearly observed from the DFT calculated partial density of states, that there are significant contributions of the S s and S p states in the Li2In2SiS6 and Li2In2GeS6 compounds as well as the Se s and Se p states in the Li2In2SiSe6 and Li2In2GeSe6 compounds, respectively. The calculated band gaps ranging from 1.92 eV to 3.24 eV of the Li2In2XY6 (X Si, Ge; Y S, Se) compounds are in good agreement with the experimental results, where the calculated band gap values are positioned in the visible region of the electromagnetic spectrum; therefore, these materials can be efficiently used for opto electronic and optical applications. Furthermore, some general trends are observed in the optical responses of the compounds, which are possibly correlated to the energy band gaps when the X cations changes from Si to Ge and the Y anions changes from S to Se in the Li2In2XY6 (X Si, Ge; Y S, Se) compounds, respectively.
author_names: Kin Mun Wong

Wilayat Khan

Muhammad Shoaib

U S Shah

Shah Haider Khan

Ghulam Murtaza
title: Ab Initio Investigation of the Structural, Electronic and Optical Properties of the Li2In2XY6 (X Si, Ge; Y S, Se) Compounds
venue: Journal of Electronic Materials
year: 2017

abstract: Abstract The energy band gap of Zn 0.75 Cd 0.25 S 1 z Se z x 0, 0.25, 0.5, 0.75 and 1.0) quaternary alloys have been calculated by using the full potential linearized augmented plane wave (FPLAPW) method and the Tran Blaha modified Becke Johnson (TBmBJ) potential. The lattice volume was first relaxed within the generalized gradient approximation (GGA) The obtained values of the band gaps are found to decrease linearly from 3.61 eV down to 2.83 eV as the content of the Se ion increases in the lattice. These values are in agreement with those reported experimentally for some of ZnS and ZnSe structures. The energies of the interband transitions were determined from the dielectric functions. It is seen that the main interband transitions peaks obtained after the TBmBJ potential is comparable with some reported experimental data. These finding supports the use of the TBmBJ potential as an accurate method in obtaining the energy band gap and the optical constants of semiconductors.
author_names: O A Yassin
title: Electronic and optical properties of Zn0.75Cd0.25S1 zSez first principles calculations based on the Tran Blaha modified Becke Johnson potential
year: 2016

abstract: Band gap engineering can efficiently improve the photocatalytic activity of semiconductors for hydrogen generation from water splitting. Herein, we present a comprehensive investigation on the geometrical structures, electronic, optical, and potential photocatalytic properties and charge carrier mobility of pristine and group IVA element doped SrIn2O4 using first principles density functional theory with the meta GGA+MBJ potential. The calculated formation energies are moderate, indicating that the synthesis of the doped structures is experimentally feasible. In addition, the energy band gaps of the group IVA element doped SrIn2O4 range from 1.67 to 3.07 eV, which satisfy the requirements for photocatalytic water splitting, except for that of the Si mono doped structure. Based on the deformation potential theory, a high charge carrier mobility of 2093 cm2 V 1 s 1 is obtained for the pristine SrIn2O4 and those of the doped structures are also large, although a decrease in the values of some are observed. The optical absorption coefficient of the doped structures in the near ultraviolet (UV) and visible light range significantly increases. Therefore, group IVA element doped SrIn2O4 are potential candidates as photocatalysts for hydrogen generation from water splitting driven by visible light.
author_names: Hai-Cai Huang

Chuanlu Yang

Mei-Shan Wang

Xiaoguang Ma

Yougen Yi
title: Group IVA element doped SrIn2O4 as potential materials for hydrogen production from water splitting with solar energy
year: 2018

author_names: Rahul Jain

Kh Gopal Krishna Singh
title: Optical and Electronic Properties of II VI Group Semiconductor Nanomaterials from Energy Gaps
year: 2018

abstract: In order to tune the optoelectronic and charge transfer properties of 4,6 di(thiophen 2 yl)pyrimidine (1) some new compounds were designed, i.e. 4,6 bis(benzo[b]thiophen 2 yl)pyrimidine (2) 4,6 bis(naphtho[2,3 b]thiophen 2 yl)pyrimidine (3) 4,6 bis(anthra[2,3 b]thiophen 2 yl)pyrimidine (4) 4,6 bis(tetraceno[2,3 b]thiophen 2 yl)pyrimidine (5) and 4,6 bis(pentaceno[2,3 b]thiophen 2 yl)pyrimidine (6) Compounds 2 6 were designed by assimilation of benzene, naphthalene, anthracene, tetracene and pentacene, respectively at both ends of compound 1. Integration of oligocene end cores reduces the energy gap resulting in a red shift in the absorption and fluorescence emission spectra. The legible intra molecular charge transfer is significant from electron rich moieties to the electron deficient core (pyrimidine) The elongation of \uppi $p conjugation led to escalate the electron affinity, lower the ionization potential and hole reorganization energy. The hole reorganization energies of compounds 3 6 exposed that these materials would be effective hole transport contenders to be used in diverse semiconductor devices.Graphical abstract
author_names: Ahmad Irfan

Abdullah G Al-Sehemi

Mohammed Ali Assiri

Muhammad Waseem Mumtaz
title: Exploring the electronic, optical and charge transfer properties of acene based organic semiconductor materials
venue: Bulletin of Materials Science
year: 2019

abstract: Abstract Density functional FP LAPW+lo method calculations were performed to explore the structural, electronic, optical, elastic, thermoelectric and thermodynamic properties of the spinel oxides ZnRh2O4 and CdRh2O4. The exchange correlation potential were described using the GGA PBEsol and TB mBJ functionals. As the first step, the optimized structural parameters, including the lattice parameter and atomic coordinates, were determined. Electronic band structure, atomic resolved l projected densities of electronic states and photon energy dependence of the linear optical functions were computed. It is found that both investigated compounds are indirect band gap semiconductors. The band gap results from the splitting of the R h 4 d 6 states into occupied R h 4 d t 2 g 6 states, which form the valence band maximum (VBM) and the empty states R h 4 d e g 0 which form the conduction band minimum (CBM) owing to the octahedral substantial crystal field. The electronic interband transitions responsible of the structures in the optical spectra were specified. Single crystal and polycrystal elastic moduli, wave sound velocities, Debye temperature, Pugh's indicator and indexes of elastic anisotropy were numerically estimated using total energy versus strain. FP LAPW+lo band structure in combination with the standard Boltzmann transport theory were employed to calculate the thermoelectric parameters, including Seebeck coefficient, electrical and thermal conductivities and figure of merit. It is found that the title compounds are potential candidates for thermoelectric applications if one can further reduce their thermal conductivities via some techniques. FP LAPW+lo approach in combination with the quasi harmonic Debye model was employed to study temperature and pressure dependences of some macroscopic physical parameters. Our obtained results in the present work are discussed in comparison with the available experimental and theoretical data. The calculated results show a good agreement with the available experimental and theoretical results.
author_names: Abdelmadjid Bouhemadou

Djamel Allali

Khaouther Boudiaf

B Al Qarni

Saad Bin-Omran

Rabah Khenata

Y Al-Douri
title: Electronic, optical, elastic, thermoelectric and thermodynamic properties of the spinel oxides ZnRh2O4 and CdRh2O4
venue: Journal of Alloys and Compounds
year: 2019

abstract: Optical band gap $E_{\mathrm{g}0} $Eg0) is a parameter of paramount importance in describing various transport and opto electronic properties of the III V type low band gap semiconductors. In the present communication, an attempt has been made to develop an energy momentum $E{ \bar{k} $E k dispersion relation for studying the density of state (DOS) and band gap related parameters. The external laser excitation has been treated as a perturbation. It has been shown theoretically that due to such excitation with different intensity (I) and wavelength \lambda (l) the band edge of the conduction band (CB) of the III V compound semiconductors moves vertically upward, indicating laser modulation (increase) of $E_{\mathrm {g}0} $Eg0 and related parameters compared to those of the normal ones (unperturbed) Therefore, in the presence of light, the original CB edge forms a pseudo CB edge above the unperturbed CB edge in the forbidden band (FB) zone. This new development of the $E{ \bar{k} $E k relationship has also been extended for the estimation of exact optical effective mass (OPEM) of an electron in some III V compound semiconductors. The OPEM variation with carrier concentration showed a continuous decreasing nature, while the corresponding variation of electron effective mass (EEM) (without laser excitation) exhibited an increasing trend. The present theoretical results would be important for the deeper understanding of the variation of OPEM with I and \lambda $l. The observed new results will also be beneficial for studying laser induced effects in semiconductor heterostructures with different applications in optoelectronic devices.
author_names: Paritosh K Chakraborty

B N Mondal

Bijay Krishna Chaudhuri
title: Laser induced modulation of optical band gap parameters in the III V type semiconductors from the density of state (DOS) calculations
venue: Pramana
year: 2019

abstract: In this paper, the electronic and optical properties of various point defects in gallium sulfide (GaS) and gallium selenide (GaSe) are studied. Various vacancy defects in each monolayer GaX (X= S, Se) include VX, VGa, 2VX, 2VGa, 1VGa1VX, 1VGa2VX, 2VGa1VX, 2VGa2VX. We compute the band structure, zero bias transmission spectrum, and dielectric function for all considered structures. The calculations are carried out by the first principles method. The calculation results indicate that the absence of S/Se atom in these semiconductors leads to the transition from an indirect band gap for the pristine materials to a direct band gap in their defective systems and the band gap energies change from 2.3 eV/2.11 eV to 1.33 eV/0.98 eV, respectively. Also, 2VX causes that the semiconductor band gap changes from indirect to direct. Furthermore, GaX monolayer is converted to a p type semiconductor in the presence of VGa. Moreover, these findings represent that some of the point defects in this system lead to magnetic states which can be employed in spintronic devices. In addition, for the defective GaX monolayers with the direct band gap, the first peak of imaginary part of the dielectric function occurs around their band gap energy. The study of intrinsic structural defects in monolayer GaX provides new opportunities for optimizing the electronic and optical properties of these materials via defect engineering.
author_names: Raziehsadat Hosseini Almadvari

Maryam Nayeri

Somayeh Fotoohi
title: Engineering of electronic and optical properties of monolayer gallium sulfide/selenide in presence of intrinsic atomic defects
year: 2020

abstract: In this paper, some electronic properties such as the electronic density of states (DOS) and energy band structure, and optical properties of the bulk and monolayer PtSe2 structure have been investigated based on the density functional theory (DFT) using full potential linearized augmented plane wave (FP LAPW) method and the modified Becke Johnson potential (mBJ) By changing the PtSe2 structure size from bulk to monolayer, there have been major changes in the electronic (DOS and band structure) and optical properties such as the dielectric function. The electronic results show that PtSe2 in the bulk state exhibits a metallic property, while its nanosheet state, PtSe2 is a semiconductor with an energy gap of about 1.5 eV. Band structure calculations showed that for PtSe2 structure in the bulk state the energy distance between G point and the K point is about 0.4 eV, so it is concluded that PtSe2 is a semi metal. The optical properties results show that the largest damping region for electromagnetic waves for a bulk PtSe2 structure in the z direction is equal to 14.02 eV. The volume plasmon energy of the PtSe2 monolayer is smaller than the plasmon energy of the bulk PtSe2. Also, the optical reflectivity of the bulk PtSe2 is larger than the optical reflectivity of the PtSe2 monolayer.
author_names: Farshad Ghasemi

R Taghavimendi

Ali Bakhshayeshi
title: Electronic and optical properties of monolayer and bulk of PtSe2
year: 2020