scholarly journals Tunable SnO2 Nanoribbon by Electric Fields and Hydrogen Passivation

2017 ◽  
Vol 2017 ◽  
pp. 1-12
Author(s):  
Xin-Lian Chen ◽  
Bao-Jun Huang ◽  
Chang-Wen Zhang ◽  
Ping Li ◽  
Pei-Ji Wang
Keyword(s):  
Band Gap ◽  
Electric Fields ◽  
Stark Effect ◽  
Tin Dioxide ◽  
Band Gaps ◽  
Hydrogen Passivation ◽  
Band Engineering ◽  
Metal Semiconductor Metal ◽  
Projector Augmented Wave ◽  
Electronic Field

Under external transverse electronic fields and hydrogen passivation, the electronic structure and band gap of tin dioxide nanoribbons (SnO2NRs) with both zigzag and armchair shaped edges are studied by using the first-principles projector augmented wave (PAW) potential with the density function theory (DFT) framework. The results showed that the electronic structures of zigzag and armchair edge SnO2NRs exhibit an indirect semiconducting nature and the band gaps demonstrate a remarkable reduction with the increase of external transverse electronic field intensity, which demonstrate a giant Stark effect. The value of the critical electric field for bare Z-SnO2NRs is smaller than A-SnO2NRs. In addition, the different hydrogen passivation nanoribbons (Z-SnO2NRs-2H and A-SnO2NRs-OH) show different band gaps and a slightly weaker Stark effect. The band gap of A-SnO2NRs-OH obviously is enhanced while the Z-SnO2NRs-2H reduce. Interestingly, the Z-SnO2NRs-OH presented the convert of metal-semiconductor-metal under external transverse electronic fields. In the end, the electronic transport properties of the different edges SnO2NRs are studied. These findings provide useful ways in nanomaterial design and band engineering for spintronics.

An energy band engineering design to enlarge the band gap of KTiOPO4 (KTP)-type sulfates via aliovalent substitution

2019 ◽  
Vol 7 (26) ◽  
pp. 8131-8138 ◽  
Author(s):  
Fei Yang ◽  
Lijuan Huang ◽  
Xiaoyu Zhao ◽  
Ling Huang ◽  
Daojiang Gao ◽  
...  
Keyword(s):  
Band Gap ◽  
Engineering Design ◽  
Energy Band ◽  
Band Gaps ◽  
Band Engineering ◽  
Aliovalent Substitution

The two fluoride sulfates RbSnFSO4 and RbSbF2SO4 derived from the famous commercial crystal KTiOPO4via aliovalent substitution exhibited remarkably enlarged band gaps.

The phosphorene under the external electronic field and strain

2017 ◽  
Vol 28 (12) ◽  
pp. 1750131
Author(s):  
Tao Wang ◽  
Yan Liu ◽  
Wen Wen ◽  
Wei Guo ◽  
You Yin
Keyword(s):  
Plane Wave ◽  
Electric Fields ◽  
Stark Effect ◽  
Photonic Devices ◽  
Generalized Gradient ◽  
Generalized Gradient Approximation ◽  
External Electric Fields ◽  
Different Strains ◽  
Bandgap Tuning ◽  
Electronic Field

Using the ab initio plane-wave ultrasoft pseudopotential method based on the generalized gradient approximation (GGA), we investigate the bandgap tuning in monolayer phosphorene in terms of applying external electric fields perpendicular to the layers. The bandgap continuously decreases with the applied electric fields, eventually rendering them metallic. The phenomenon is explained by the giant stark effect. The interlayer P-P distance also result in the semiconductor-to-metal transition. The phosphorene exhibits the significant bandgap tuning ability under different strains with 5% variation. Our investigations show the bandgap change for the fabrication of novel electronic and photonic devices.

scholarly journals The Band-Gap Studies of Short-Period CdO/MgO Superlattices

2021 ◽  
Vol 16 (1) ◽  
Author(s):  
Ewa Przeździecka ◽  
P. Strąk ◽  
A. Wierzbicka ◽  
A. Adhikari ◽  
A. Lysak ◽  
...  
Keyword(s):  
Band Gap ◽  
Layer Thickness ◽  
Energy Gap ◽  
Band Gaps ◽  
Short Period ◽  
Wide Range ◽  
Salt Structure ◽  
Short Period Superlattices ◽  
Direct Band ◽  
Sublayer Thickness

AbstractTrends in the behavior of band gaps in short-period superlattices (SLs) composed of CdO and MgO layers were analyzed experimentally and theoretically for several thicknesses of CdO sublayers. The optical properties of the SLs were investigated by means of transmittance measurements at room temperature in the wavelength range 200–700 nm. The direct band gap of {CdO/MgO} SLs were tuned from 2.6 to 6 eV by varying the thickness of CdO from 1 to 12 monolayers while maintaining the same MgO layer thickness of 4 monolayers. Obtained values of direct and indirect band gaps are higher than those theoretically calculated by an ab initio method, but follow the same trend. X-ray measurements confirmed the presence of a rock salt structure in the SLs. Two oriented structures (111 and 100) grown on c- and r-oriented sapphire substrates were obtained. The measured lattice parameters increase with CdO layer thickness, and the experimental data are in agreement with the calculated results. This new kind of SL structure may be suitable for use in visible, UV and deep UV optoelectronics, especially because the energy gap can be precisely controlled over a wide range by modulating the sublayer thickness in the superlattices.

THE BAND GAP ESTIMATION OF ZINC MANGANESE PHOSPHATE GLASSES

2008 ◽  
Vol 22 (12) ◽  
pp. 1265-1272 ◽  
Author(s):  
S. A. SIDDIQI ◽  
M. A. GHAURI ◽  
M. J. S. BAIG
Keyword(s):  
Electric Fields ◽  
Spectral Dependence ◽  
Transport Mechanism ◽  
Phosphate Glasses ◽  
Band Gaps ◽  
Spectral Energy ◽  
Charge Transport Mechanism ◽  
Optical Band Gaps ◽  
Manganese Phosphate ◽  
Made In

Zinc manganese phosphate glasses ( ZnO - MnO - P 2 O 5) of different compositions are synthesized. The optical band gaps are measured in the UV-VIS region. Photoconduction measurements are also made in the spectral energy range 1.5–6.2 eV. At various applied electric fields, the values of the energy band gaps have been deduced from the spectral dependence curves. Furthermore, the band gaps at zero applied voltage were also obtained for different compositions. The charge transport mechanism in these glasses is studied under the Mott's model.

Effect of Double Defects on Transmission Spectra of One-Dimensional Photonic Crystals

2010 ◽  
Vol 663-665 ◽  
pp. 725-728 ◽  
Author(s):  
Yuan Ming Huang ◽  
Qing Lan Ma ◽  
Bao Gai Zhai ◽  
Yun Gao Cai
Keyword(s):  
Photonic Crystals ◽  
Band Gap ◽  
Theoretical Calculations ◽  
Stop Band ◽  
Band Gaps ◽  
Characteristic Matrix ◽  
Frequency Range ◽  
Defect Band ◽  
One Dimensional ◽  
The One

Considered the model of the one-dimensional photonic crystals (1-D PCs) with double defects, the refractive indexes (n2’, n3’ and n2’’, n3’’) of the double defects were 2.0, 4.0 and 4.0, 2.0 respectively. With parameter n2=1.5, n3=2.5, by theoretical calculations with characteristic matrix method, the results shown that for a certain number (14 was taken) of layers of the 1-D PCs, when the double defects abutted, there was a defect band gap in the stop band gap, while when the double defects separated, there occurred two defect band gaps in the stop band gap; besides, with the separation of the two defects, the transmittance of the double defect band gaps decreased gradually. In addition, in this progress, the frequency range of the stop band gap has a little increase from 0.092 to 0.095.

CdTe Thin Film Solar Cells: The CdS/SnO2 Front Contact

2001 ◽  
Vol 668 ◽  
Author(s):  
J. Fritsche ◽  
S. Gunst ◽  
A. Thiβen ◽  
R. Gegenwart ◽  
A. Klein ◽  
...  
Keyword(s):  
Thin Film ◽  
Solar Cells ◽  
Band Gap ◽  
Photoelectron Spectroscopy ◽  
Tin Dioxide ◽  
Surface Preparation ◽  
Thin Film Solar Cells ◽  
Subsequent Formation ◽  
Coated Glass ◽  
Preparation Conditions

ABSTRACTTin dioxide (SnO2) coated glass is the commonly used substrate for thin film solar cells based on CdTe absorbers. We have investigated the properties of the CdS/SnO2 interface by X-ray and ultraviolet photoelectron spectroscopy. SnO2 coated glass substrates as used for solar cell preparation were cleaned by different procedures such as derinsing, sputtering, heating and annealing in oxygen atmosphere. Different surface properties with a strongly dependent number of defects in the SnO2 band gap are identified. CdS films were deposited stepwise by thermal evaporation to determine the electronic interface properties for different surface preparation conditions. Comparative barrier heights at the CdSSnO2 contact are found for most surface pretreatments. The Fermi level position in these cases is situated in the SnO2 band gap. A different interface behaviour is determined for sputter cleaned SnO2 surfaces, which is attributed to the formation of oxygen vacancies during sputtering and subsequent formation of an interfacial SnOxSy compound.

scholarly journals Visible emission from Er-doped SnO2 thin films deposited by sol-gel

Cerâmica ◽  
2007 ◽  
Vol 53 (326) ◽  
pp. 187-191 ◽  
Author(s):  
L. P. Ravaro ◽  
E. A. Morais ◽  
L. V. A. Scalvi ◽  
M. Siu Li
Keyword(s):  
Thin Film ◽  
Electric Fields ◽  
Tin Dioxide ◽  
Sol Gel ◽  
Precursor Solution ◽  
Dip Coating ◽  
Sno2 Thin Film ◽  
Rare Earth Ion ◽  
Electron Hole ◽  
Er Doped

Emission from Er-doped SnO2 thin film deposited via sol-gel by the dip coating technique is obtained in the range 500-700 nm with peak at 530 nm (green). Electron-hole generation in the tin dioxide matrix is used to promote the rare-earth ion excitation. Evaluation of crystallite dimensions through X-ray diffraction results leads to nanoscopic size, what could play a relevant role in the emission spectra. The electron-hole mechanism is also responsible for the excitation of the transition in the 1540 nm range in powders obtained from the same precursor solution of films. The thin film matrix presents a very useful shape for technological application, since it allows integration in optical devices and the application of electric fields to operate electroluminescent devices.

scholarly journals Piezoelectric Level Splitting in GaInN/GaN Quantum Wells

1999 ◽  
Vol 4 (S1) ◽  
pp. 357-362
Author(s):  
C. Wetzel ◽  
T. Takeuchi ◽  
H. Amano ◽  
I. Akasaki
Keyword(s):  
Quantum Wells ◽  
Electric Fields ◽  
High Performance ◽  
Stark Effect ◽  
Electronic Band Structure ◽  
Multiple Quantum Well ◽  
Multiple Quantum ◽  
Large Set ◽  
Electronic Band ◽  
Level Splitting

Identification of the electronic band structure in AlInGaN heterostructures is the key issue in high performance light emitter and switching devices. In device-typical GaInN/GaN multiple quantum well samples in a large set of variable composition a clear correspondence of transitions in photo- and electroreflection, as well as photoluminescence is found. The effective band offset across the GaN/GaInN/GaN piezoelectric heterointerface is identified and electric fields from 0.23 - 0.90 MV/cm are directly derived. In the bias voltage dependence a level splitting within the well is observed accompanied by the quantum confined Stark effect. We furthermore find direct correspondence of luminescence bands with reflectance features. This indicates the dominating role of piezoelectric fields in the bandstructure of such typical strained layers.

scholarly journals Energy Gaps in BN/GNRs Planar Heterostructure

Materials ◽  
2021 ◽  
Vol 14 (17) ◽  
pp. 5079
Author(s):  
Jinyue Guan ◽  
Lei Xu
Keyword(s):  
Phase Transition ◽  
Boron Nitride ◽  
Band Gap ◽  
Lattice Mismatch ◽  
Tight Binding ◽  
Graphene Nanoribbon ◽  
Band Gaps ◽  
Energy Gaps ◽  
Local Potentials

Using the tight-binding approach, we study the band gaps of boron nitride (BN)/ graphene nanoribbon (GNR) planar heterostructures, with GNRs embedded in a BN sheet. The width of BN has little effect on the band gap of a heterostructure. The band gap oscillates and decreases from 2.44 eV to 0.26 eV, as the width of armchair GNRs, nA, increases from 1 to 20, while the band gap gradually decreases from 3.13 eV to 0.09 eV, as the width of zigzag GNRs, nZ, increases from 1 to 80. For the planar heterojunctions with either armchair-shaped or zigzag-shaped edges, the band gaps can be manipulated by local potentials, leading to a phase transition from semiconductor to metal. In addition, the influence of lattice mismatch on the band gap is also investigated.

Non-Dirac Chern insulators with large band gaps and spin-polarized edge states

Nanoscale ◽  
2018 ◽  
Vol 10 (18) ◽  
pp. 8569-8577 ◽  
Author(s):  
Y. Xue ◽  
J. Y. Zhang ◽  
B. Zhao ◽  
X. Y. Wei ◽  
Z. Q. Yang
Keyword(s):  
Band Gap ◽  
Band Gaps ◽  
Edge States ◽  
Half Metallic ◽  
Spin Polarized ◽  
Chern Insulators

A non-Dirac Chern insulator with a large band gap (244 meV) and half-metallic edge states was realized in a PbC/MnSe heterostructure.

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