Conduction bands of GaxIn1−xAs and InAsxSb1−xalloys

1970 ◽  
Vol 48 (4) ◽  
pp. 463-469 ◽  
Author(s):  
William M. Coderre ◽  
John C. Woolley
Keyword(s):  
Electrical Conductivity ◽  
Band Structure ◽  
Valence Band ◽  
Conduction Band ◽  
High Temperatures ◽  
Hall Coefficient ◽  
Solidus Temperature ◽  
Energy Separation ◽  
Conduction Bands ◽  
Valence Bands

Measurements of Hall coefficient and electrical conductivity have been made on alloys of the systems GaxIn1−xAs and InAsxSb1−xover a range of temperature from 200 up to 950 °K or to 20° below the solidus temperature of the particular specimen, whichever was lower. These data have then been analyzed in terms of equations involving all the occupied conduction and valence bands in the manner described previously by Coderre and Woolley. The results give the variation of the energy separation from the valence band of the (000) conduction-band minimum as a function of the composition and temperature for both alloy systems. For a certain range of x in the InAsxSb1−x alloys, a transition to the gray-tin band structure is observed at high temperatures.

Conduction bands of GaxIn1–x Sb alloys

1969 ◽  
Vol 47 (22) ◽  
pp. 2553-2564 ◽  
Author(s):  
William M. Coderre ◽  
John C. Woolley
Keyword(s):  
Electrical Conductivity ◽  
Band Gap ◽  
Hall Coefficient ◽  
Solidus Temperature ◽  
Energy Separation ◽  
Trial And Error ◽  
Unknown Parameters ◽  
Alloy Scattering ◽  
Conduction Bands ◽  
Valence Bands

Measurements of Hall coefficient and electrical conductivity have been made on alloys of the system GaxIn1–xSb over a range of temperature from 100 °K up to 950 °K or to 20° below the solidus temperature of the particular specimen, whichever was the lower. These data have then been analyzed in terms of equations involving three conduction and two valence bands, the important unknown parameters in the equations being determined by a trial and error fitting technique. The results give the variation of the energy separation from the valence band of the [Formula: see text] and [Formula: see text] conduction band minima, as well as the main (000) band gap as a function of the composition and temperature. Also determined from the analysis are the (000) electron mobilities, which are found to vary linearly with composition, indicating that alloy scattering has negligible effect on the mobility values.

New Evidence for the Second Conduction Band in 4H SiC

2017 ◽  
Vol 897 ◽  
pp. 250-253 ◽  
Author(s):  
Walter Klahold ◽  
Charles Tabachnick ◽  
Gabriel Freedman ◽  
Robert P. Devaty ◽  
Wolfgang J. Choyke
Keyword(s):  
Conduction Band ◽  
Energy Gap ◽  
Free Exciton ◽  
Epitaxial Films ◽  
Energy Separation ◽  
Orbit Splitting ◽  
Conduction Bands ◽  
Spin Orbit Splitting ◽  
New Evidence ◽  
Absorption Measurements

Differential absorption measurements were taken on ultra-pure boule pieces and epitaxial films of 4H SiC. The energy range of particular interest is from 3.40 eV to 3.52 eV. The free exciton energy gap associated with the second lowest conduction band at the M point in the Brillouin zone was determined to be EGX-2 = 3.4107 eV. This value is obtained from phonon assisted free exciton transitions involving the second conduction band measured in transmission with polarization E⊥c. The energy separation of the two lowest conduction bands is determined to be 144 ± 2 meV. Some replica peaks attributable to the spin orbit splitting in the valence band are also seen.

The k·p Interaction Calculations of Conduction Band and Valence Band of InN Materials

2014 ◽  
Vol 1015 ◽  
pp. 235-239
Author(s):  
Shao Guang Dong ◽  
Guo Jie Chen ◽  
Xin Chen
Keyword(s):  
Dispersion Relation ◽  
Valence Band ◽  
Conduction Band ◽  
Electron Concentration ◽  
Absorption Edge ◽  
Electron Interaction ◽  
Impurity Interaction ◽  
Consistent Picture ◽  
Valence Bands

Thek·pinteraction of the conduction band and valence band of InN materials was calculated in this paper. The nonparabolicity of the conduction band is more pronounced, because the conduction band feels stronger perturbation from the valence bands whenEgis smaller orEPis larger. The increase in absorption edge with increasing electron concentration was calculated by the dispersion relation. In the calculation, the conduction band renormalization effects due to electron interaction and electron-ionized impurity interaction are also taken into account. A good consistent picture is established in describing the conduction band of InN based on thek·pinteraction.

Conduction band of InAs

1968 ◽  
Vol 46 (15) ◽  
pp. 1669-1675 ◽  
Author(s):  
Clarence C. Y. Kwan ◽  
John C. Woolley
Keyword(s):  
Magnetic Fields ◽  
Hall Effect ◽  
Valence Band ◽  
Conduction Band ◽  
Infrared Absorption ◽  
Room Temperature ◽  
Impurity Content ◽  
Temperature Measurements ◽  
Energy Separation ◽  
Transverse Magnetoresistance

Measurements of transverse magnetoresistance and Hall effect have been made at 4.2 °K on various In2Se3-doped and In2Te3-doped InAs polycrystalline specimens with magnetic fields up to 3.2 Wb/m2. An analysis of the results gives values of electron concentrations n0 and n1 and mobilities μ0 and μ1 for both the (000) and [Formula: see text] conduction-band minima. From the values of n0 and n1, the energy separation of the (000) and [Formula: see text] minima E01 of pure InAs has been determined to be 0.70 + 0.02 eV and is found to decrease with increasing impurity content, the rate of reduction being 0.13 ± 0.02 eV/at.% selenium and 0.17 ± 0.03 eV/at.% tellurium. Room-temperature measurements of electroreflectance and infrared absorption have also been made, and these indicate that the variation in E01 is due to the movement of the (000) conduction-band minimum relative to the valence band.

scholarly journals Conduction Band Engineering of Half-Heusler Thermoelectrics Using Orbital Chemistry

2021 ◽  
Author(s):  
Shuping Guo ◽  
Shashwat Anand ◽  
Madison K. Brod ◽  
Yongsheng Zhang ◽  
G. Jeffrey Snyder
Keyword(s):  
Valence Band ◽  
Conduction Band ◽  
High Symmetry ◽  
Electron Configuration ◽  
Band Engineering ◽  
Conduction Bands ◽  
Orbital Phase ◽  
The Difference ◽  
P Type ◽  
Orbital Character

Semiconducting half-Heusler (HH, XYZ) phases are promising thermoelectric materials owing to their versatile electronic properties. Because the valence band of half-Heusler phases benefit from the valence band extrema at several high-symmetry points in the Brillouin zone (BZ), it is possible to engineer better p-type HH materials through band convergence. However, the thermoelectric studies of n-type HH phases have been lagging behind since the conduction band minimum is always at the same high-symmetry point (X) in the BZ, giving the impression that there is little opportunity for band engineering. Here we study the n-type orbital diagram of 69 HHs, and show that there are two competing conduction bands with very different effective masses actually at the same X point in the BZ, which can be engineered to be converged. The two conduction bands are dominated by the d orbitals of X and Y atoms, respectively. The energy offset between the two bands depends on the difference in electron configuration and electronegativity of the X and Y atoms. Based on the orbital phase diagram, we provide the strategy to engineer the conduction band convergence by mixing the HH compounds with the reverse band offsets. We demonstrate the strategy by alloying VCoSn and TaCoSn. The V0.5Ta0.5CoSn mixture presents the high conduction band convergence and corresponding significantly larger density-of-states effective mass than either VCoSn or TaCoSn. Our work indicates that analyzing the orbital character of band edges provides new insight into engineering thermoelectric performance of HH compounds.

Exploring Complex Chalcogenides for Thermoelectric Applications

2000 ◽  
Vol 626 ◽  
Author(s):  
Ying C. Wang ◽  
Francis J. DiSalvo
Keyword(s):  
Band Structure ◽  
Physical Properties ◽  
Thermoelectric Properties ◽  
Thermoelectric Materials ◽  
Crystal Symmetry ◽  
Synthesis And Characterization ◽  
Conduction Bands ◽  
Valence Bands ◽  
Binary Compounds

ABSTRACTOur research on ternary / quaternary chalcogenides for thermoelectric applications has lead to the identification of new interesting compounds and better understanding of the chemistry and physical properties of complex chalcogenides. The chemical, geometric, electronic diversity and flexibility has been well demonstrated in BaBiSe3 and Sr4Bi6Se13 type compounds. This presents both a challenge and more opportunity in controlling and optimizing the thermoelectric properties of these complex chalcogenides, compared with elemental and binary compounds. The importance of multivalley band structure in thermoelectric materials is emphasized. Only compounds with high crystal symmetry have the possibility of having a large number of degenerate valleys in the conduction bands or peaks in the valence bands, respectively. However, most of the complex chalcogenides crystallize in low crystal symmetry. An Edisonian method of exploratory synthesis and characterization may be the working approach to find good thermoelectric materials with ZT higher than 4.

scholarly journals Unraveling the origins of conduction band valley degeneracies in Mg2Si1−xSnx thermoelectrics

2016 ◽  
Vol 18 (2) ◽  
pp. 939-946 ◽  
Author(s):  
Chang-Eun Kim ◽  
Aloysius Soon ◽  
Catherine Stampfl
Keyword(s):  
Density Functional Theory ◽  
Band Structure ◽  
Conduction Band ◽  
Density Functional ◽  
Hybrid Density Functional Theory ◽  
Functional Theory ◽  
Conduction Bands ◽  
Orbital Nature ◽  
Hybrid Density Functional

The origin of the enhanced band valley degeneracy for Mg2Si1−xSnx (MSS) are examined using a temperature-broadened, orbital-projected band structure as calculated by hybrid density-functional theory (DFTHSE06). For MSS alloys, varying xSn modulates the orbital nature of the conduction bands, and couples with the sublattice strain which directly manipulates the degree of the effective degeneracy.

Effective Densities of States in Conduction and Valence Bands in a-Si

1993 ◽  
Vol 297 ◽  
Author(s):  
JoŽE Furlan ◽  
Franc Smole ◽  
Pavle PopoviĆ
Keyword(s):  
Band Structure ◽  
Valence Band ◽  
Computer Simulations ◽  
Gaussian Distribution ◽  
Transport Equations ◽  
Densities Of States ◽  
Extended States ◽  
Valence Bands

Effective densities of states in conduction and valence band, Nc and Nv, are usually set to a fixed value of 1019 to 1020 cm−3 in all computer simulations of a-Si structures. In this contribution the densities Nc and Nv are analytically expressed for different selected extended states distributions. The derivatives d(lnNc)/dx and d(lnNv)/dx, representing specific terms in transport equations, are expressed as function of position dependent band structure. The effect of an increased disorder in heterojunction is simulated by Gaussian distribution of states in a linearly graded heterojunction region.

Uniaxial Stress Effects On Valence Band Structures Of GaN

1997 ◽  
Vol 482 ◽  
Author(s):  
A. A. Yamaguchi ◽  
Y. Mochizuki ◽  
C. Sasaoka ◽  
A. Kimura ◽  
M. Nido ◽  
...  
Keyword(s):  
Valence Band ◽  
Uniaxial Stress ◽  
Reflectance Spectroscopy ◽  
Experimental Results ◽  
Energy Separation ◽  
Strain Effect ◽  
Deformation Potential ◽  
Stress Effects ◽  
Polarization Characteristics ◽  
Valence Bands

AbstractValence band modification by uniaxial stress in GaN is investigated by reflectance spectroscopy. It is observed that the energy separation between the A and B valence bands increases with the applied uniaxial stress in the c-plane. Changes of the wavefunctions by the stress are also investigated by the polarization characteristics of the reflectance spectra. The experimental results are analyzed on the basis of k•p theory, and deformation potential D5 is experimentally determined as -3.3 eV. It is indicated that the uniaxial strain effect could be utilized for improving GaN-based laser performance.

Band structure investigation of chalcopyrite CuInSe2(001) by angle-resolved photoelectron spectroscopy

2005 ◽  
Vol 865 ◽  
Author(s):  
Ralf Hunger ◽  
Christian Pettenkofer
Keyword(s):  
Electronic Structure ◽  
Band Structure ◽  
Valence Band ◽  
Photoelectron Spectroscopy ◽  
Bulk Composition ◽  
Synchrotron Source ◽  
Band Dispersion ◽  
Low Energy Electron ◽  
Copper Chalcopyrite ◽  
Valence Bands

AbstractClean and ordered chalcopyrite CuInSe2 surfaces are a precondition for the study of the electronic structure by angle-resolved photoelectron spectroscopy. The preparation of welldefined CuInSe2(001) surfaces by the combination of molecular beam epitaxy and a selenium capping and decapping process is described. The surface structure of CuInSe2 epilayers with different bulk composition is compared and analysed by low-energy electron diffraction.Employing near-stoichiometric surfaces, the valence electronic structure of CuInSe2 was investigated by angle-resolved photoelectron spectroscopy at the synchrotron source BESSY 2. This is the first study of the valence band structure of a copper chalcopyrite semiconductor material by photoelectron spectroscopy. The valence band dispersion along τT, i.e. the [001] direction, was investigated by a variation of the excitation energy from 10 to 35 eV under normal emission, and the band dispersion along τT, i.e. the [110] direction, was analysed by angular scans with hv = 13 eV.The valence bands derived from antibonding and bonding Se4p-Cu3d hybrid orbitals, nonbonding Cu3d states and In-Se hybrid states are clearly indentified. The strongest dispersion is found for the topmost valence band with a bandwidth of ∼0.7 eV from τ to T. From τ to N, the observed dispersion was 0.5 eV. The experimental valence bands are discussed in relation to calculated band structures in the literature.

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