scholarly journals (112) Surface of CuInSe2Thin Films with Doped Cd Atoms

2015 ◽  
Vol 2015 ◽  
pp. 1-7
Author(s):  
Bo Yin ◽  
Chaogang Lou
Keyword(s):  
Thin Films ◽  
Electronic Structure ◽  
Valence Band ◽  
Electronic Structures ◽  
Formation Energy ◽  
Valence Band Maximum ◽  
Band Maximum ◽  
Doping Behavior

The doping behavior of Cd atoms in the CuInSe2thin films and their influences on electronic structures are investigated. The doped Cd atoms replace Cu atoms and prefer to stay at the (112) surface of the thin films. They combine with Cu vacancies to form defect pairs due to low formation energy. The Cd atom does not by itself modify significantly the electronic structure of the surface, but the defect pairs have important influences. They result in a down shift of valence band maximum and form a hole barrier at the surface, which can prevent holes from reaching the surface and reduce the recombination of carriers.

The “electron crystal” behavior in copper chalcogenides Cu2X (X = Se, S)

2017 ◽  
Vol 5 (10) ◽  
pp. 5098-5105 ◽  
Author(s):  
Yongxing Sun ◽  
Lili Xi ◽  
Jiong Yang ◽  
Lihua Wu ◽  
Xun Shi ◽  
...  
Keyword(s):  
Transport Properties ◽  
Valence Band ◽  
Electronic Structures ◽  
Electrical Transport ◽  
Valence Band Maximum ◽  
Electrical Transport Properties ◽  
Band Maximum ◽  
Copper Chalcogenides ◽  
Structural Fluctuation ◽  
Electron Crystal

In Cu2Se, the structural fluctuation of the Cu sites have minor effects on the electronic structures around valence band maximum. The electrical transport properties of Cu2Se are mainly determined by the Se sublattice; Cu atoms serve as the carrier reservoirs.

Structural and Electronic Structure of SnO2 by the First-Principle Study

2012 ◽  
Vol 725 ◽  
pp. 265-268 ◽  
Author(s):  
Minoru Oshima ◽  
Kenji Yoshino
Keyword(s):  
Electronic Structure ◽  
Electronic Properties ◽  
Valence Band ◽  
Conduction Band ◽  
Valence Band Maximum ◽  
First Principle ◽  
Band Maximum ◽  
First Principle Calculations ◽  
Calculation Results ◽  
Good Agreement

We performed first-principle calculations to investigate the effects of F, Cl and Sb impurities on the electronic properties of SnO2. We obtained, firstly, the electronic structure of SnO2, a valence band maximum of SnO2is an O 2p orbital and a conduction band minimum was an antibonding Sn 5s and O 2p orbitals dominantly. Secondly, those impurites doped SnO2was obtained the electronic structure. The F, Cl and Sb impurities as n-type dopants exhibited shallow donors. This calculation results were in good agreement with our prvious experiment that we obtained the low resistivity SnO2.

scholarly journals Machine Learning Chemical Guidelines for Engineering Electronic Structures in Half-Heusler Thermoelectric Materials

Research ◽  
2020 ◽  
Vol 2020 ◽  
pp. 1-8 ◽  
Author(s):  
Maxwell T. Dylla ◽  
Alexander Dunn ◽  
Shashwat Anand ◽  
Anubhav Jain ◽  
G. Jeffrey Snyder
Keyword(s):  
Machine Learning ◽  
Valence Band ◽  
Electronic Structures ◽  
Electronic Band Structure ◽  
Valence Band Maximum ◽  
Electronic Band ◽  
Band Maximum ◽  
Orbital Phase ◽  
Valence Bands ◽  
P Type

Half-Heusler materials are strong candidates for thermoelectric applications due to their high weighted mobilities and power factors, which is known to be correlated to valley degeneracy in the electronic band structure. However, there are over 50 known semiconducting half-Heusler phases, and it is not clear how the chemical composition affects the electronic structure. While all the n-type electronic structures have their conduction band minimum at either the Γ- or X-point, there is more diversity in the p-type electronic structures, and the valence band maximum can be at either the Γ-, L-, or W-point. Here, we use high throughput computation and machine learning to compare the valence bands of known half-Heusler compounds and discover new chemical guidelines for promoting the highly degenerate W-point to the valence band maximum. We do this by constructing an “orbital phase diagram” to cluster the variety of electronic structures expressed by these phases into groups, based on the atomic orbitals that contribute most to their valence bands. Then, with the aid of machine learning, we develop new chemical rules that predict the location of the valence band maximum in each of the phases. These rules can be used to engineer band structures with band convergence and high valley degeneracy.

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.

scholarly journals An antibonding valence band maximum enables defect-tolerant and stable GeSe photovoltaics

2021 ◽  
Vol 12 (1) ◽  
Author(s):  
Shun-Chang Liu ◽  
Chen-Min Dai ◽  
Yimeng Min ◽  
Yi Hou ◽  
Andrew H. Proppe ◽  
...  
Keyword(s):  
Solar Cells ◽  
Valence Band ◽  
Surface Passivation ◽  
Defect Density ◽  
Perovskite Solar Cells ◽  
Valence Band Maximum ◽  
Ambient Conditions ◽  
Band Maximum ◽  
Point Tracking ◽  
Power Point

AbstractIn lead–halide perovskites, antibonding states at the valence band maximum (VBM)—the result of Pb 6s-I 5p coupling—enable defect-tolerant properties; however, questions surrounding stability, and a reliance on lead, remain challenges for perovskite solar cells. Here, we report that binary GeSe has a perovskite-like antibonding VBM arising from Ge 4s-Se 4p coupling; and that it exhibits similarly shallow bulk defects combined with high stability. We find that the deep defect density in bulk GeSe is ~1012 cm−3. We devise therefore a surface passivation strategy, and find that the resulting GeSe solar cells achieve a certified power conversion efficiency of 5.2%, 3.7 times higher than the best previously-reported GeSe photovoltaics. Unencapsulated devices show no efficiency loss after 12 months of storage in ambient conditions; 1100 hours under maximum power point tracking; a total ultraviolet irradiation dosage of 15 kWh m−2; and 60 thermal cycles from −40 to 85 °C.

scholarly journals Synthesis of ZnO doped high valence S element and study of photogenerated charges properties

RSC Advances ◽  
2019 ◽  
Vol 9 (8) ◽  
pp. 4422-4427 ◽  
Author(s):  
Lijing Zhang ◽  
Xiufang Zhu ◽  
Zhihui Wang ◽  
Shan Yun ◽  
Tan Guo ◽  
...  
Keyword(s):  
Uniform Distribution ◽  
Valence Band ◽  
Valence Band Maximum ◽  
Band Maximum

The uniform distribution of S dopants elevated the valence band maximum by mixing S 3p with the upper valence band states of ZnO. The valence band maxima of S–ZnO was 0.37 eV higher than that of ZnO.

Valence-band maximum in the layered semiconductor WSe2: Application of constant-energy contour mapping by photoemission

1996 ◽  
Vol 53 (24) ◽  
pp. R16152-R16155 ◽  
Author(s):  
Th. Straub ◽  
K. Fauth ◽  
Th. Finteis ◽  
M. Hengsberger ◽  
R. Claessen ◽  
...  
Keyword(s):  
Valence Band ◽  
Valence Band Maximum ◽  
Layered Semiconductor ◽  
Constant Energy ◽  
Band Maximum ◽  
Contour Mapping ◽  
Energy Contour
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