scholarly journals Моделирование туннельного переноса электронов в системе полупроводник-кристаллический диэлектрик-Si(111)

2018 ◽  
Vol 52 (8) ◽  
pp. 900
Author(s):  
М.И. Векслер
Keyword(s):  
Energy Distribution ◽  
Valence Band ◽  
Conduction Band ◽  
Wave Vector ◽  
Transverse Wave ◽  
Carrier Transport ◽  
Metal Gate ◽  
Analogous Structure ◽  
Conduction Bands ◽  
Account Due

AbstractTunneling carrier transport through a thin insulator (e.g., CaF_2) layer between a Si(111) substrate and a semiconductor gate is theoretically investigated. Along with the conservation of a large transverse wave vector of tunneling particles, the limitation imposed on the availability of states in the gate is taken into account. Due to this limitation, the tunneling currents at low insulator bias are weaker than in an analogous structure with a metal gate electrode. The same feature leads to a change in the shape of the energy distribution of tunneling electrons, both in transport between the substrate and gate conduction bands and during the Si(111) conduction band–gate valence band transfer.

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.

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.

scholarly journals Electric Field Induced Twisted Bilayer Graphene Infrared Plasmon Spectrum

Nanomaterials ◽  
2021 ◽  
Vol 11 (9) ◽  
pp. 2433
Author(s):  
Jizhe Song ◽  
Zhongyuan Zhang ◽  
Naixing Feng ◽  
Jingang Wang
Keyword(s):  
Electric Field ◽  
External Electric Field ◽  
Valence Band ◽  
Conduction Band ◽  
Bilayer Graphene ◽  
Physical Mechanisms ◽  
Conduction Bands ◽  
Twisted Bilayer Graphene ◽  
The Difference ◽  
Plasmon Spectrum

In this work, we investigate the role of an external electric field in modulating the spectrum and electronic structure behavior of twisted bilayer graphene (TBG) and its physical mechanisms. Through theoretical studies, it is found that the external electric field can drive the relative positions of the conduction band and valence band to some extent. The difference of electric field strength and direction can reduce the original conduction band, and through the Fermi energy level, the band is significantly influenced by the tunable electric field and also increases the density of states of the valence band passing through the Fermi level. Under these two effects, the valence and conduction bands can alternately fold, causing drastic changes in spectrum behavior. In turn, the plasmon spectrum of TBG varies from semiconductor to metal. The dielectric function of TBG can exhibit plasmon resonance in a certain range of infrared.

A Sub-Ev Resolution Soft-X-Ray Spectrometer for a Transmision Electron Microscope to Obtain the Density of States of the Valence Band

2001 ◽  
Vol 7 (S2) ◽  
pp. 228-229
Author(s):  
M. Terauchi ◽  
H. Yamamoto ◽  
M. Tanaka
Keyword(s):  
Valence Band ◽  
Conduction Band ◽  
Density Of States ◽  
Energy Resolution ◽  
High Energy ◽  
High Energy Resolution ◽  
Partial Density ◽  
X Ray ◽  
Conduction Bands ◽  
Resolution Electron

We developed a high energy-resolution electron energy-loss spectroscopy (EELS) microscope to investigate electronic structures from specified small specimen areas [1]. EELS gives us information of the dielectric properties and the partial density of states (DOS) of the conduction band. Together with the DOS of the conduction band (unoccupied states), the DOS of the valence band (occupied states) is imperative to understand the whole electronic structure. Unfortunately, the DOS of the valence band cannot be reached directly by EELS.A partial DOS of the valence band can be obtained by fluorescent X-ray emission spectroscopy (XES). A conventional EELS instrument attached to a TEM usually takes spectra with an energy resolution of about 1 eV, by which the DOS of conduction bands has been studied using ELNES until now. Thus, an energy resolution of about 1 eV is at least necessary for the study of the DOS of the valence band.

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

2022 ◽  
Author(s):  
Shuping Guo ◽  
Shashwat Anand ◽  
Madison K. Brod ◽  
Yongsheng Zhang ◽  
G. Jeffrey Snyder
Keyword(s):  
Electronic Properties ◽  
Valence Band ◽  
Conduction Band ◽  
Thermoelectric Materials ◽  
Band Engineering

Semiconducting half-Heusler (HH, XYZ) phases are promising thermoelectric materials owing to their versatile electronic properties. Because the valence band of half-Heusler phases benefits from the valence band extrema at several...

scholarly journals Влияние ионов неодима (III) на фотолюминесценцию сульфидов кадмия и цинка в полиакрилатной матрице

2022 ◽  
Vol 56 (2) ◽  
pp. 229
Author(s):  
В.П. Смагин ◽  
А.А. Исаева ◽  
Е.А. Шелепова
Keyword(s):  
Methyl Methacrylate ◽  
Valence Band ◽  
Conduction Band ◽  
Structural Defects ◽  
Excitation Spectra ◽  
Nanoscale Particles ◽  
Semiconductor Structures ◽  
Semiconductor Particles ◽  
Optically Transparent

Nanoscale particles ZnS:Nd3+, CdS:Nd3+ and (Zn,Cd)S:Nd3+ were synthesized and doped in a polymerizing methyl methacrylate medium during the production of optically transparent polyacrylate composites of the composition PMMA/ZnS:Nd3+, PMMA/CdS:Nd3+ and PMMA/(Zn,Cd)S:Nd3+. The excitation of photoluminescence (FL) and FL of semiconductor structures in composites is associated with the transition of electrons from the valence band to the conduction band and to the levels of structural defects of semiconductor particles, followed by recombination at these levels. Based on changes in the excitation spectra of FL and FL composites, assumptions are made about the structure of particles, the distribution of Nd3+ ions in it and their effect on photoluminescence.

POLARIZATION PROPERTIES OF SYNCHROTRON RADIATION IN THE STUDY OF ANISOTROPIC INSULATING CRYSTALS

2002 ◽  
Vol 09 (01) ◽  
pp. 469-472
Author(s):  
V. N. KOLOBANOV ◽  
I. A. KAMENSKIKH ◽  
V. V. MIKHAILIN ◽  
I. N. SHPINKOV ◽  
D. A. SPASSKY ◽  
...  
Keyword(s):  
Crystal Structure ◽  
Optical Properties ◽  
Energy Transfer ◽  
Synchrotron Radiation ◽  
Valence Band ◽  
Conduction Band ◽  
Electronic States ◽  
Absorption Region ◽  
New Information ◽  
Fundamental Absorption Region

The optical properties of a wide series of the tungstates with the scheelite and wolframite crystal structure at the threshold of the fundamental absorption region were studied. New information about the influence of the electronic states forming the bottom of the conduction band and the top of the valence band on the formation of emission centers and mechanisms of energy transfer to these centers was obtained.

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