Boron nitride (BN), energy gap, width of valence band and related data, cubic modification

2005 ◽  
pp. 1-12
Author(s):  
Keyword(s):  
Boron Nitride ◽  
Valence Band ◽  
Energy Gap ◽  
Related Data ◽  
Gap Width

Laser-Doped SiC as Wireless Remote Gas Sensor Based on Semiconductor Optics

2012 ◽  
Vol 717-720 ◽  
pp. 1195-1198
Author(s):  
Geunsik Lim ◽  
Tariq Manzur ◽  
Aravinda Kar
Keyword(s):  
Valence Band ◽  
Energy Gap ◽  
Gas Sensing ◽  
Optical Signal ◽  
Acceptor Level ◽  
Spectral Bands ◽  
Sensing Applications ◽  
Electro Optic ◽  
Midwave Infrared ◽  
P Type

An uncooled SiC-based electro-optic device is developed for gas sensing applications. P-type dopants Ga, Sc, P and Al are incorporated into an n-type crystalline 6H-SiC substrate by a laser doping technique for sensing CO2, CO, NO2 and NO gases, respectively. Each dopant creates an acceptor energy level within the bandgap of the substrate so that the energy gap between this acceptor level and the valence band matches the quantum of energy emitted by the gas of interest. The photons of the gas excite electrons from the valence band to the acceptor level, which alters the electron density in these two states. Consequently, the refractive index of the substrate changes, which, in turn, modifies the reflectivity of the substrate. This change in reflectivity represents the optical signal of the sensor, which is probed remotely with a laser such as a helium-neon laser. Although the midwave infrared (3-5 mm) band is studied in this paper, the approach is applicable to other spectral bands.

Spin polarized conduction and valence band states in GdN

MRS Advances ◽  
2017 ◽  
Vol 2 (3) ◽  
pp. 153-158 ◽  
Author(s):  
Muhammad Azeem
Keyword(s):  
Valence Band ◽  
Optical Transmission ◽  
Energy Gap ◽  
Ferromagnetic State ◽  
Spin Splitting ◽  
Transmission Spectra ◽  
Temperature Dependent ◽  
Spin Polarized ◽  
Transmission Measurements ◽  
Optical Transmission Spectra

AbstractOptical transmission spectra are collected in the ferromagnetic state of GdN at various temperatures. The temperature dependent extinction coefficient extracted from the transmission measurements show that the conduction and valence band states are spin polarized. The results confirm the LSDA+U estimates of the energy gap associated with the majority/minority-spins and also the magnitude of the spin splitting.

scholarly journals Estimates of Impact Ionization Coefficients in Superlattice-Based Mid-Wavelength Infrared Avalanche Photodiodes

2003 ◽  
Vol 799 ◽  
Author(s):  
C. H. Grein ◽  
K. Abu El-Rub ◽  
M. E. Flatté ◽  
H. Ehrenreich
Keyword(s):  
Valence Band ◽  
Impact Ionization ◽  
Energy Gap ◽  
Avalanche Photodiodes ◽  
Threshold Energy ◽  
Type Ii ◽  
Band Engineering ◽  
Type Ii Superlattice ◽  
Low Threshold ◽  
Ionization Coefficients

ABSTRACTWe describe band engineering strategies to either enhance or suppress electron-initiated impact ionization relative to hole-initiated impact ionization in type II superlattice mid-wavelength infrared avalanche photodiodes. The strategy to enhance electron-initiated impact ionization involves placing a high density of states at approximately one energy gap above the bottom of the conduction band and simultaneously removing valence band states from the vicinity of one energy gap below the top of the valence band. This gives the electrons a low threshold energy and the holes a high one. The opposite strategy enhances hole-initiated impact ionization. Estimates of the electron (α) and hole (β) impact ionization coefficients predict that α/β>>1 in the first type of superlattice and α/β<<1 in the second type.

Weak morphology dependent valence band structure of boron nitride

2013 ◽  
Vol 114 (5) ◽  
pp. 054306 ◽  
Author(s):  
Chunyi Zhi ◽  
Shigenori Ueda ◽  
Haibo Zeng ◽  
Xuebin Wang ◽  
Wei Tian ◽  
...  
Keyword(s):  
Boron Nitride ◽  
Band Structure ◽  
Valence Band ◽  
Valence Band Structure

Photoswitching of the Optical and Electrical Properties of One-dimensional π-Electron Systems

2002 ◽  
Vol 57 (1-2) ◽  
pp. 89-93
Author(s):  
Nikolai Tyutyulkov ◽  
Fritz Dietz
Keyword(s):  
Electrical Conductivity ◽  
Electrical Properties ◽  
Light Absorption ◽  
Energy Gap ◽  
Optical And Electrical Properties ◽  
Electron Systems ◽  
Elementary Unit ◽  
One Dimensional ◽  
Correlation Correction ◽  
Gap Width

The photoswitching of the energy gap width of the isomeric forms of photoresponsive polymers with homomiclear photochrome diaryletheue elementary units is investigated theoretically, taking into account the correlation correction. It is shown that a real switching of electrical conductivity (insulator ⇔ semiconductor or conductor) can not be realized with polymers with alternant homomiclear π -electron systems within the elementary unit. A change and tuning-in of the light absorption is possible in most cases.

Two valence band evidence and thermal energy gap in Pb1−xSnx Te

1968 ◽  
Vol 27 (2) ◽  
pp. 72-73 ◽  
Author(s):  
M. Ocio ◽  
H.J. Albany
Keyword(s):  
Valence Band ◽  
Thermal Energy ◽  
Energy Gap

scholarly journals The electronic structure of the atom as a classification criterion of mineral technogenic waste

2021 ◽  
Vol 2131 (4) ◽  
pp. 042095
Author(s):  
A Sakharova ◽  
L Maslennikova
Keyword(s):  
Electronic Structure ◽  
Building Materials ◽  
Energy Gap ◽  
Chemical Elements ◽  
Raw Materials ◽  
Waste Recycling ◽  
Model Systems ◽  
Technogenic Waste ◽  
The Impact ◽  
Gap Width

Abstract Today, the total scientific classification of solid industrial waste is absent because of their diversity. The task of universal of mineral technogenic waste recycling is complicated by the difference in their composition. The nature of the chemical elements that make up building materials is always taken into account to predict their properties. In this regard, the purpose of the study was to determine the classification characteristics of mineral technogenic waste recycling on the basis of natural-scientific ideas about the electronic structure of the atom. Studies were conducted on model systems with ceramic oxides entering s-, p-, d- elements in ceramic matrix to test the impact of the electronic structure of the mineral waste cation on operational characteristics of building materials. The experimental results showed that the strength of the samples changes in the series s → p → d of the belonging of the introduced oxide cation to the electronic family. Additionally, such an indicator as the energy-gap width was used to study the nature of the contacting solid phases. It is possible to identify which substances in technogenic raw materials have the greatest effect on the performance of the material in value of the energy-gap width.

scholarly journals Adsorption of the Guanine Molecule Over the Pristine, Nb- and Au-doped Boron Nitride Nanosheets: A DFT Study

2021 ◽  
Author(s):  
Meryem Derdare ◽  
ABDELGHANI BOUDJAHEM
Keyword(s):  
Boron Nitride ◽  
Recovery Time ◽  
Theoretical Study ◽  
Energy Gap ◽  
State Theory ◽  
Surface Reactivity ◽  
Slight Variation ◽  
Short Recovery Time ◽  
Low Sensitivity ◽  
Homo Lumo

Abstract A theoretical study has been performed onto the pristine, Nb- and Au-doped boron nitride (BN) nanosheets using DFT calculations with the B3LYP-D3 method in order to evaluate their stabilities and electronic properties. The interaction of the guanine molecule with these clusters was also examined in aim to determine their adsorption properties. The calculations show that the HOMO-LUMO energy gap (Eg) of the BN nanosheet was strongly decreased upon its doping with Nb and Au atoms, implying a strong enhancement in its surface reactivity. The interaction of the guanine with the BN sheet was found to be weak, which leads a slight variation in its energy gap, therefore a low sensitivity of this nanosheet toward the guanine was observed. The guanine adsorption over the NbBN cluster is very strong, and the calculated adsorptions energies are in the range of – 36.7 to – 60.2 kcal mol-1, suggesting a great chemical adsorption. For the AuBN cluster, the guanine molecule has been chemisorbed onto its surface with adsorption energies varying of – 24.2 to – 38.4 kcal mol-1, which are lower than those obtained for the NbBN cluster. Upon adsorption proceess, the energy gap of the NbBN cluster was greatly increased, which leads to a decrease in its electric conductivity, thereby it cannot be a suitable sensor for the guanine molecule. On the contrary, the energy gap of the AuBN cluster was reduced by the effect of the guanine adsorption on its surface, indicating an increase in its electrical conductivity, thus the AuBN cluster possess a great electronic sensitivity to the guanine molecule. Based on the transition state theory, the recovery time of the guanine from the AuBN cluster was estimated of 27.6 s, reflecting that the Au-doped BN nanosheet could be employed as an appropriate nanomaterial for the guanine molecule detection with a short recovery time.

Studies on the Geometric and Electronic Structures of SiC Polytypes

2014 ◽  
Vol 926-930 ◽  
pp. 234-237
Author(s):  
Fu Chun Zhang ◽  
Xian Hui Zhong ◽  
Xing Xiang Ruan ◽  
Wei Hu Zhang
Keyword(s):  
Energy Level ◽  
Valence Band ◽  
Brillouin Zone ◽  
Density Functional ◽  
Energy Gap ◽  
Wide Band ◽  
Orbital Energy ◽  
First Principle Calculation ◽  
System Energy ◽  
Orbital Energy Level

SiC poly-type geometric structure, electronic structure and energy have been subjected to systematic study based on first principle calculation method given in density functional theory. After calculation, the energy results show that 4H-SiC system energy is the lowest and stablest, while 2H-SiC system energy is the highest and unstablest; the calculation results of the band structure show that six SiC poly-types are indirect wide band gap semiconductor, with valence band top on point Γ of Brillouin zone, conduction band bottom on point M of Brillouin zone; with the increase of hexagonality, the energy gap and valence band width are gradually getting smaller, with largest splitting of orbital energy level on 2H-SiC valence band top, reaching to 0.122 eV, while the splitting of orbital energy level on 8H-SiC valence band top is the smallest, with 0.027 eV only.

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