scholarly journals First-principle calculations of effective mass of silicon crystal with vacancy defects

2016 ◽  
Vol 34 (4) ◽  
pp. 916-923 ◽  
Author(s):  
Shuying Zhong ◽  
Musheng Wu ◽  
Xueling Lei
Keyword(s):  
Valence Band ◽  
Crystalline Silicon ◽  
Valence Band Maximum ◽  
Energy Bands ◽  
Electron Hole ◽  
Vacancy Defects ◽  
Band Maximum ◽  
Effective Masses ◽  
Jahn Teller ◽  
Gap States

AbstractThe energy band structures and electron (hole) effective masses of perfect crystalline silicon and silicon with various vacancy defects are investigated by using the plane-wave pseudopotential method based on density functional theory. Our results show that the effect of monovacancy and divacancy on the energy band structure of crystalline silicon is primarily reflected in producing the gap states and the local states in valence band maximum. It also causes breaking the symmetry of energy bands resulting from the Jahn-Teller effect, while only producing the gap states for the crystalline silicon with hexavacancy ring. However, vacancy point defects could not essentially affect the effective masses that are derived from the native energy bands of crystalline silicon, except for the production of defect states. Simultaneously, the Jahn-Teller distortions only affect the gap states and the local states in valence band maximum, but do not change the symmetry of conduction band minimum and the nonlocal states in valence band maximum, thus the symmetry of the effective masses. In addition, we study the electron (hole) effective masses for the gap states and the local states in valence band maximum.

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

Effects of the band offset on interfacial deep levels

1988 ◽  
Vol 3 (1) ◽  
pp. 164-166
Author(s):  
Richard P. Beres ◽  
Roland E. Allen ◽  
John D. Dow
Keyword(s):  
Valence Band ◽  
Energy Levels ◽  
Valence Band Maximum ◽  
Deep Levels ◽  
Band Offset ◽  
Valence Band Offset ◽  
Band Maximum ◽  
Antisite Defects

The energy levels of antisite defects at a GaAs/Ge (110) interface are calculated and shown to be essentially unaltered with respect to the GaAs valence band maximum by different choices of the valence band offset.

CATION ANTISITE DEFECTS AND ANTISITE-BASED-DEFECT COMPLEXES IN GaAs

1990 ◽  
Vol 04 (18) ◽  
pp. 1133-1136
Author(s):  
S.B. ZHANG
Keyword(s):  
Structural Change ◽  
Fermi Level ◽  
Valence Band ◽  
Valence Band Maximum ◽  
Recent Theory ◽  
Band Maximum ◽  
Defect Complexes ◽  
Atomic Exchange ◽  
Antisite Defects

Recent theory predicted that the Ga and B antisites in GaAs are bistable. As the Fermi level is lowered towards the valence-band maximum, a structural change from fourfold to threefold coordination will occur. The Ga antisite will undergo an atomic exchange in the presence of an As interstitial.

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.

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