Electrons and holes in semiconductors

2021 ◽  
pp. 321-336
Author(s):  
Geoffrey Brooker
Keyword(s):  
Valence Band ◽  
Conduction Band ◽  
Band Theory ◽  
Effective Masses ◽  
Queue Model ◽  
Dirac Distribution ◽  
Incorrect Model ◽  
Group Velocities

“Electrons and holes in semiconductors” applies band theory to electrons in the conduction band, and to holes in the valence band. Holes are described by an upside-down Fermi–Dirac distribution. An incorrect model (cinema-queue model) for a hole is discredited and replaced by a correct discussion. Both (conduction-band) electrons and (valence-band) holes are examples of quasi-particles. Both can be assigned their own group velocities and effective masses.

First-principle calculation of the electronic structure, DOS and effective mass TlInSe2

2017 ◽  
Vol 31 (14) ◽  
pp. 1750155 ◽  
Author(s):  
N. A. Ismayilova ◽  
G. S. Orudzhev ◽  
S. H. Jabarov
Keyword(s):  
Electronic Structure ◽  
Effective Mass ◽  
Valence Band ◽  
Conduction Band ◽  
Density Of States ◽  
Valence Band Maximum ◽  
First Principle ◽  
Band Maximum ◽  
Effective Masses ◽  
Structure Density

The electronic structure, density of states (DOS), effective mass are calculated for tetragonal TlInSe2 from first principle in the framework of density functional theory (DFT). The electronic structure of TlInSe2 has been investigated by Quantum Wise within GGA. The calculated band structure by Hartwigsen–Goedecker–Hutter (HGH) pseudopotentials (psp) shows both the valence band maximum and conduction band minimum located at the T point of the Brillouin zone. Valence band maximum at the T point and the surrounding parts originate mainly from 6s states of univalent Tl ions. Bottom of the conduction band is due to the contribution of 6p-states of Tl and 5s-states of In atoms. Calculated DOS effective mass for holes and electrons are [Formula: see text], [Formula: see text], respectively. Electron effective masses are fairly isotropic, while the hole effective masses show strong anisotropy. The calculated electronic structure, density of states and DOS effective masses of TlInSe2 are in good agreement with existing theoretical and experimental results.

Direct evaluation of hole effective mass of SnS–SnSe solid solutions with ARPES measurement

2021 ◽  
Author(s):  
Issei Suzuki ◽  
Zexin Lin ◽  
Sakiko Kawanishi ◽  
Kiyohisa Tanaka ◽  
Yoshitaro Nose ◽  
...  
Keyword(s):  
Effective Mass ◽  
Valence Band ◽  
Thermoelectric Properties ◽  
Solid Solutions ◽  
Photoemission Spectroscopy ◽  
Direct Evaluation ◽  
Hole Effective Mass ◽  
Single Crystalline ◽  
Angle Resolved Photoemission Spectroscopy ◽  
Effective Masses

Valence band dispersions of single-crystalline SnS1-xSex solid solutions were observed by angle-resolved photoemission spectroscopy (ARPES). The hole effective masses, crucial factors in determining thermoelectric properties, were directly evaluated. They decrease...

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.

scholarly journals Photocatalytic properties of a new Z-scheme system BaTiO3/In2S3 with a core–shell structure

RSC Advances ◽  
2019 ◽  
Vol 9 (20) ◽  
pp. 11377-11384 ◽  
Author(s):  
Kaili Wei ◽  
Baolai Wang ◽  
Jiamin Hu ◽  
Fuming Chen ◽  
Qing Hao ◽  
...  
Keyword(s):  
Charge Transfer ◽  
Valence Band ◽  
Conduction Band ◽  
Shell Structure ◽  
Band Edge ◽  
Conduction Band Edge ◽  
Core Shell ◽  
Valence Band Edge ◽  
Core Shell Structure ◽  
Positive Valence

It's highly desired to design an effective Z-scheme photocatalyst with excellent charge transfer and separation, a more negative conduction band edge (ECB) than O2/·O2− (−0.33 eV) and a more positive valence band edge (EVB) than ·OH/OH− (+2.27 eV).

scholarly journals Ab initioStudies of Electronic Structure of Defects in PbTe

2005 ◽  
Vol 864 ◽  
Author(s):  
Salameh Ahmad ◽  
Daniel Bilc ◽  
S.D. Mahanti ◽  
M.G. Kanatzidis
Keyword(s):  
Electronic Structure ◽  
Valence Band ◽  
Conduction Band ◽  
Density Of States ◽  
Resonance State ◽  
Interesting Case ◽  
The Other ◽  
Defect States ◽  
Strong Resonance ◽  
Structure Calculations

AbstractAb initioelectronics structure calculations have been carried out in a series of RPb2n-1Te2n, n=16, compounds to understand the nature of “defect” states introduced by R where R = vacancy, monovalent Na, K, Rb, Cs, Ag atoms and divalent Cd atoms. We find that the density of states (DOS) near the top of the valence band and the bottom of the conduction band get significantly modified. The Na atom seems to perturb this region least (ideal acceptor in PbTe) and the other monovalent atoms enhance the DOS near the top of the valence band. Cd is an interesting case, since it introduces a strong resonance state near the bottom of the conduction band.

Bulk and Surface Electronic Structure of GaN Measured Using Angle-Resolved Photoemission, Soft X-ray Emission and Soft X-ray Absorption

1996 ◽  
Vol 449 ◽  
Author(s):  
Kevin E. Smith ◽  
Sarnjeet S Dhesi ◽  
Laurent-C. Duda ◽  
Cristian B Stagarescu ◽  
J. H. Guo ◽  
...  
Keyword(s):  
Electronic Structure ◽  
Valence Band ◽  
Absorption Spectra ◽  
Conduction Band ◽  
Brillouin Zone ◽  
Emission Spectra ◽  
Partial Density ◽  
High Symmetry ◽  
X Ray ◽  
X Ray Absorption

ABSTRACTThe electronic structure of thin film wurtzite GaN has been studied using a combination of angle resolved photoemission, soft x-ray absorption and soft x-ray emission spectroscopies. We have measured the bulk valence and conduction band partial density of states by recording Ga L- and N K- x-ray emission and absorption spectra. We compare the x-ray spectra to a recent ab initio calculation and find good overall agreement. The x-ray emission spectra reveal that the top of the valence band is dominated by N 2p states, while the x-ray absorption spectra show the bottom of the conduction band as a mixture of Ga 4s and N 2p states, again in good agreement with theory. However, due to strong dipole selection rules we can also identify weak hybridization between Ga 4s- and N 2p-states in the valence band. Furthermore, a component to the N K-emission appears at approximately 19.5 eV below the valence band maximum and can be identified as due to hybridization between N 2p and Ga 3d states. We report preliminary results of a study of the full dispersion of the bulk valence band states along high symmetry directions of the bulk Brillouin zone as measured using angle resolved photoemission. Finally, we tentatively identify a non-dispersive state at the top of the valence band in parts of the Brillouin zone as a surface state.

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