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Theoretical Study on the Origins of the Gap bowing in MgxZn1–xO Alloys

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Modeling and Numerical Simulation of Material Science 2012年第3期2卷 60-66页

作者： F. Z. Aoumeur-Benkabou M. Ameri A. Kadoun K. Benkabou Laboratoire de Microscopie Microanalyse et Spectroscopie Moleculaire Faculté des Sciences. Département de Physique Sidi-bel-abbes Algeria Djilali-Liabes University of Sidi-Bel-Abbes Algeria

The full potential linear muffin-tin orbital (FP-LMTO) method was applied to study the structural and electronic properties of the compounds MgO, ZnO and their alloy MgxZn1–xO in the zincblende and NaCl structures. Results are obtained using the local density approximation (LDA), the ground-state properties like lattice constant and bulk modulus obtained agree very well with experimental and other theoretical calculations. The effect of composition on lattice constant from Vegard’s law and the bulk modulus was investigated. The microscopic origins of the gap bowing were explained by using the approach of Zunger and co-workers. It is concluded that the energy band gap bowing is primarily due to chemical charge-transfer effect. Contribution of volume deformation and structural relaxation to the gap bowing parameter is found to be very small.

关键词： FP-LMTO Method Structural and Electronic Properties MgxZn1–xO Alloy bowing

The bowing Parameters of CaχMg1-χO Ternary Alloys

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Journal of Modern Physics 2014年第15期5卷 1546-1551页

作者： Sinem Erden Gulebaglan Emel Kilit Dogan Murat Aycibin Mehmet Nurullah Secuk Bahattin Erdinc Harun Akkus Department of Electric Program Vacational School of Van Yuzuncu Yil University Van Turkey Physics Department Faculty of Sciences Yüzüncü Yil University Van Turkey

On the basis of first principles calculations using density functional theory, we explore the structural and electronic properties of two binaries: CaO and MgO in rock salt structures. Structural properties of the semiconductor CaχMg1-χO alloys are derived from total-energy minimization within the General Gradient Approximation. The band gap bowing parameters dependence is very powerful Calcium composition. The results offer that an average bowing parameter of CaχMg1-χO alloys is b = ~0.583$ eV. We analyzed the volume deformation, charge transfer and structural relaxation effects of the CaχMg1-χO alloys.

关键词： Density Functional Theory Ternary Alloys Band-Gap bowing Parameter

First-principles study of the band gap tuning and doping control in CdSexTe1-x alloy for high efficiency solar cell

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Chinese Physics B 2019年第8期28卷 16-21页

作者： Jingxiu Yang Su-Huai Wei Department of Materials Science and Engineering Jilin Jianzhu UniversityChangchun 130118China Beijing Computational Science Research Center Beijing 100193China

CdTe is one of the leading materials for low cost,high efficiency thin-film solar cells with a nearly ideal band gap of 1.48 ***,its solar to electricity power conversion efficiency(PCE)is hindered by the relatively low open circuit voltage(VOC)due to intrinsic defect related ***,we propose that alloying CdTe with CdSe could possibly improve the solar cell performance by reducing the"ideal"band gap of CdTe to gain more short-circuit current from long-wavelength absorption without sacrificing much *** the hybrid functional calculation,we find that the minimum band gap of the CdTe1-xSex alloy can be reduced from 1.48 eV at x=0 to 1.39 eV at x=0.32,and most of the change come from the lowering of the conduction band *** also show that the formation of the alloy can improve the p-type doping of CuCdimpurity based on the reduced effective formation energy and nearly constant effective transition energy level,thus possibly enhance VOC,thus PCE.

关键词： alloy bowing effect doping Ⅱ-Ⅵsemiconductors

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The band structures of BSb and B_xGa_(1-x)Sb alloys

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Science China(Physics,Mechanics & Astronomy) 2009年第6期52卷 843-847页

作者： XIONG DePing1, ZHOU ShouLi2, WANG Qi3, LUO Li1, HUANG YongQing3 & REN XiaoMin3 1 School of Physics and Optoelectronic Engineering, Guangdong University of Technology, Guangzhou 510006, China 2 College of Information Engineering, Zhejiang University of Technology, Hangzhou 310032, China 3 Key Laboratory of Optical Communication and Lightwave Technologies Ministry of Education, Beijing University of Posts and Telecommunications, Beijing 100876, China School of Physics and Optoelectronic Engineering Guangdong University of Technology Guangzhou China College of Information Engineering Zhejiang University of Technology Hangzhou China Key Laboratory of Optical Communication and Lightwave Technologies Ministry of Education Beijing University of Posts and Telecommunications Beijing China

The band structures of BSb and BxGa1-xSb alloys are studied using first-principles calculations in the generalized gradient approximation. By SQS-8 supercells to model a random alloy, the direct transition energy-gap (Γ15v- Γ1c) bowing of 3.0 eV is obtained for BxGa1-xSb alloys in x = 0-50%, in x = 0-11% the energy-gap is the band-gap and increases by 7 meV/%B with boron composition increasing; by SQS-16 supercells the bowing parameter is about 1.9 eV in x = 0-12.5%. The formation enthalpies of mixing, ΔH, are calculated for BxGa1-xAs and BxGa1-xSb alloys. A comparison of enthalpies indicates that BxGa1-xSb films with boron composition of 7% may be possible.

关键词： band-gap bowing parameter boride alloys

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Bandgap energy determination of In As Sb epilayers grown by molecular beam epitaxy on Ga As substrates

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Progress in Natural Science:Materials International 2019年第4期29卷 472-476页

作者： K.Murawski E.Gomó?ka M.Kopytko K.Grodecki K.Michalczewski ?.Kubiszyn W.Gawron P.Martyniuk A.Rogalski J.Piotrowski Institute of Applied Physics Military University of Technology Vigo System S.A.

InAsSb ternary alloys can be considered as an alternative to HgCdTe for mid-wavelength,as well as long-wavelength infrared *** energy bandgap exhibits nonlinearity versus Sb composition,and hence the correct determination of its value is necessary for the effective design and simulation of optoelectronic *** commonly used expression on the InAsSb energy bandgap provided by Wieder and Clawson overestimated energy bandgap values at high *** this paper,we present two modified empirical relationships which are based on the experimental data obtained in our laboratory and published *** are correct for a wide range of Sb molar composition and *** nonlinearity of the energy gap is described with the adequate bowing *** data collected in our experiment,for samples grown on lattice mismatched GaAs substrates,fits well with a bowing factor of C=0.72 *** minimum bandgap energy that can be reached at room temperature is about 73 meV for a Sb mole fraction,x=*** comparison,the bandgap at low temperatures collected in the literature for samples grown on lattice-matched GaSb substrates is smaller than the measured values in our experiment and fits well with a parabola with C=0.9 eV.

关键词： InAsSb Bandgap energy bowing Ⅲ-Ⅴ ternary alloys Infrared detectors

Using humeral nail for surgical reconstruction of femur in adolescents with osteogenesis imperfecta

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World Journal of Orthopedics 2017年第9期8卷 735-740页

作者： Paphon Sa-ngasoongsong Tanyawat Saisongcroh Chanika Angsanuntsukh Patarawan Woratanarat Pornchai Mulpruek Department of Orthopedics Faculty of Medicine Ramathibodi Hospital Mahidol University

Osteogenesis imperfecta(OI) is a rare inherited connective tissue disorder caused by mutation of collagen which results in a wide spectrum of clinical manifestations including long bone fragility fractures and deformities. While the treatment for these fractures was recommended as using intramedullary fixation for minimizing stress concentration, the selection of the best implant in the adolescent OI patients for the surgical reconstruction of femur was still problematic, due to anatomy distortion and implant availability. We are reporting the surgical modification by using a humeral nail for femoral fixation in three adolescent OI patients with favorable outcomes.

关键词： Osteogenesis imperfecta Adolescent Humeral nail Femoral fracture Femoral bowing deformity

Understanding the Properties of Silicon Solar Cells Aluminium Contact Layers and Its Effect on Mechanical Stability

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Materials Sciences and Applications 2013年第2期4卷 118-127页

作者： V. A. Popovich M. P. F. H. L. van Maris M. Janssen I. J. Bennett I. M. Richardson Department of Materials Science & Engineering Delft University of Technology Delft The Netherlands Department of Mechanical Engineering Eindhoven University of Technology Eindhoven The Netherlands Solar Energy PV Module Technology Energy Research Centre of the Netherlands Petten The Netherlands.

As the thickness of silicon solar wafer and solar cells becomes thinner, the cells are subjected to high stress due to the thermal coefficient mismatch induced by metallization process. Handling and bowing problems associated with thinner wafers become increasingly important, as these can lead to cells cracking and thus to high yield losses. The goal of this work to provide experimental understanding of Al rear side microstructure development and mechanical properties as well as correlate the obtained results with fracture behaviour of the cell. It is shown that the aluminium back contact has a complex microstructure, consisting of five main components: 1) the back surface field layer;2) a eutectic layer;3) spherical (3 - 5 μm) hypereutectic Al-Si particles surrounded by a thin aluminium oxide layer (200 nm);4) a bis- muth-silicate glass matrix;and 5) pores (14 vol%). It was concluded that the eutectic layer thickness and waviness depends on Al particle size, amount of Al paste and textured surface roughness of silicon wafers. The Young’s modulus of the Al-Si particles is estimated by nano-indentation and the overall Young’s modulus is estimated on the basis of bowing measurements and found to be ~43 GPa. It was found, that there is a relation between aluminium paste composition, eutectic layer thickness, mechanical strength and bowing of solar cells. Three main parameters were found to affect the mechanical strength of mc-silicon solar cells with an aluminium contact layer, namely the eutectic layer thickness and uniformity, the Al layer thickness (which results from the Al particle size and its distribution), and the amount of porosity and the bismuth glass fraction.

关键词： Al Back Contact Fracture Strength bowing Young’s Modulus Silicon Solar Cell

Ab InitioCalculations Study of Structural and Electronic Properties of Ternary Alloy AlxIn1–xAs

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Materials Sciences and Applications 2012年第10期3卷 674-683页

作者： Mohammed Ameri Fatima Boufadi Amina Touia Meriem Faudil Djelloul Hachemane Keltouma Boudia Amel Slamani Adjadj Aze-Eddine Physics department Faculty of science Djillali Liabes University of Sidi Bel Abbes Algeria Physics Department Faculty of Science Djillali Liabes University Sidi Bel Abbes Algeria

First principles calculations of the structural and electronic properties of AlAs, InAs and their alloy AlxIn1–xAs have been performed using the full-potential linear muffin-tin orbital (FP-LMTO) [1] method within density functional theory (DFT) [2,3]. We used the local density approximation (LDA) [4] within the generalized gradient correction (GGA) [5] to calculate the electronic structure at equilibrium volume. The effect of composition on lattice constants, bulk modulus and band gap were investigated. Deviations of the lattice constants from Vegard’s law and the bulk modulus were observed for this alloy. The microscopic origins of the gap bowing were explained by using the approach of Zunger and co-workers [6-9].

关键词： FP-LMTO DFT Arsenide Compounds Band Gap bowing Effective Masses

FP-LMTO Calculations of Structural and Electronic Properties of Alkaline-Earth Chalcogenides Alloys AY:A = Ca, Sr, Ba;Y = S

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Materials Sciences and Applications 2012年第12期3卷 861-871页

作者： Mohammed Ameri Keltouma Boudia Abbes Rabhi Samir Benaissa Yarub Al-Douri Abdelmadjid Rais Djelloul Hachemane Department of Mathematics University of Sidi Bel Abbes Sidi Bel Abbes Algeria Department of Physics University Djillali Liabes Sidi Bel Abbes Algeria Laboratory of Statistics and Stochastic Processes University Djillali Liabes Sidi Bel Abbes Algeria Nono Institute of Electronic Engineering University Malaysia Perlis Kangar Malaysia

The structural and the electronic properties of the ternary SrxCa1-xS, BaxCa1-xS and BaxSr1-xS alloys have been calculated using the full-potential linear muffin-tin-orbital (FP-LMTO) method based on density functional theory, within both local density approximation (LDA) and generalized gradient approximation (GGA). The calculated equilibrium lattice constants and bulk modulus are compared with previous results. The concentration dependence of the electronic band structure and the direct and indirect band gaps are investigated. Using the approach of Zunger and co-workers, the microscopic origins of the band gap bowing are investigated also. A reason is found from the comparison of our results with other theoretical calculations.

关键词： SrS BaS CaS Semiconductors FP-LMTO Alloys bowing Parameter