From the Kohn–Sham band gap to the fundamental gap in solids. An integer electron approach

2017 ◽  
Vol 19 (24) ◽  
pp. 15639-15656 ◽  
Author(s):  
E. J. Baerends
Keyword(s):  
Band Gap ◽  
Conduction Band ◽  
Electron Crystal

The upshift Δ of the level at the bottom of the conduction band (the LUMO) from the neutral N-electron crystal to the negative N + 1 system, and therefore the fundamental gap εLUMO(N + 1) − εHOMO(N) = I − A, can be calculated simply and cheaply from the response part of vxc.

scholarly journals Effect of Yb Concentration on the Structural, Magnetic and Optoelectronic Properties of Yb Doped ZnO: First Principles Calculation

2021 ◽  
Author(s):  
Mohamed Achehboune ◽  
Mohammed Khenfouch ◽  
Issam Boukhoubza ◽  
Issam Derkaoui ◽  
Bakang Moses Mothudi ◽  
...  
Keyword(s):  
Band Gap ◽  
Conduction Band ◽  
Density Functional ◽  
Blue Shift ◽  
First Principles Calculation ◽  
Theoretical Research ◽  
Generalized Gradient ◽  
Functional Theory ◽  
Doped Zno ◽  
Good Agreement

Abstract Density functional theory-based investigation of the electronic, magnetic, and optical characteristics in pure and ytterbium (Yb) doped ZnO has been carried out by the plane-wave pseudopotential technique with generalized gradient approximation. The calculated lattice parameters and band gap of pure ZnO are in good agreement with the experimental results. The energy band-gap increases with the increase of Yb concentration. The Fermi level moves upward into the conduction band after doping with Yb, which shows the properties of an n-type se miconductor. New defects were created in the band-gap near the conduction band attributed to the Yb-4f states. The magnetic properties of ZnO were found to be affected by Yb doping; ferromagnetic property was observed for 4.17% Yb due to spin polarization of Yb-4f electrons. The calculated optical properties imply that Yb doped causes a blue shift of the absorption peaks, significantly enhances the absorption of the visible light, and the blue shift of the reflectivity spectrum was observed. Besides, a better transmittance of approximately 88% was observed for 4.17% Yb doped ZnO system. The refractive index and the extinction coefficient were observed to decrease as the Yb dopant concentration increased. As a result, we believe that our findings will be useful in understanding the doping impact in ZnO and will motivate further theoretical research.

Study of Band Alignment at CBD-CdS/Cu(In1-xGax)Se2 (x = 0.2 - 1.0) Interfaces by Photoemission and Inverse Photoemission Spectroscopy

2007 ◽  
Vol 1012 ◽  
Author(s):  
Shimpei Teshima ◽  
Hirotake Kashiwabara ◽  
Keimei Masamoto ◽  
Kazuya Kikunaga ◽  
Kazunori Takeshita ◽  
...  
Keyword(s):  
Band Gap ◽  
Conduction Band ◽  
Valence Band Maximum ◽  
Band Gap Energy ◽  
Band Alignment ◽  
Photoemission Spectroscopy ◽  
Gap Energy ◽  
Conduction Band Offset ◽  
Inverse Photoemission ◽  
Inverse Photoemission Spectroscopy

AbstractDependence of band alignments at interfaces between CdS by chemical bath deposition and Cu(In1-xGax)Se2 by conventional 3-stage co-evaporation on Ga substitution ratio x from 0.2 to 1.0 has been systematically studied by means of photoemission spectroscopy (PES) and inverse photoemission spectroscopy (IPES). For the specimens of the In-rich CIGS, conduction band minimum (CBM) by CIGS was lower than that of CdS. Conduction band offset of them was positive about +0.3 ~ +0.4 eV. Almost flat conduction band alignment was realized at x = 0.4 ~ 0.5. On the other hand, at the interfaces over the Ga-rich CIGS, CBM of CIGS was higher than that of CdS, and CBO became negative. The present study reveals that the decrease of CBO with a rise of x presents over the wide rage of x, which results in the sign change of CBO around 0.4 ~ 0.45. In the Ga-rich interfaces, the minimum of band gap energy, which corresponded to energy spacing between CBM of CdS and valence band maximum of CIGS, was almost identical against the change of band gap energy of CIGS. Additionally, local accumulation of oxygen related impurities was observed at the Ga-rich samples, which might cause the local rise of band edges in central region of the interface.

Exploring Burstein–Moss type effects in nickel doped hematite dendrite nanostructures for enhanced photo-electrochemical water splitting

2019 ◽  
Vol 21 (36) ◽  
pp. 20463-20477 ◽  
Author(s):  
Soniya Gahlawat ◽  
Jaspreet Singh ◽  
Ashok Kumar Yadav ◽  
Pravin P. Ingole
Keyword(s):  
Optical Properties ◽  
Band Gap ◽  
Water Splitting ◽  
Conduction Band ◽  
Optical Band Gap ◽  
Doped Semiconductors ◽  
Electrochemical Water Splitting

The Burstein–Moss suggests which that the optical band gap of degenerately doped semiconductors increases when all states close to the conduction band get populated is important to obtain different optical properties for the same material.

scholarly journals Optical properties of nanocrystal films: blue shifted transitions as signature of strong coupling

2020 ◽  
Vol 2 (1) ◽  
pp. 384-393
Author(s):  
Erik S. Skibinsky-Gitlin ◽  
Salvador Rodríguez-Bolívar ◽  
Marco Califano ◽  
Francisco M. Gómez-Campos
Keyword(s):  
Optical Properties ◽  
Band Gap ◽  
Strong Coupling ◽  
Conduction Band ◽  
Red Shift ◽  
Nanocrystal Films ◽  
Interdot Coupling

Large blue shifts in the intra-conduction-band transitions and the red shift of the band gap absorption are both the manifestation of strong interdot coupling in the film.

scholarly journals Phase transition-induced band edge engineering of BiVO4 to split pure water under visible light

2015 ◽  
Vol 112 (45) ◽  
pp. 13774-13778 ◽  
Author(s):  
Won Jun Jo ◽  
Hyun Joon Kang ◽  
Ki-Jeong Kong ◽  
Yun Seog Lee ◽  
Hunmin Park ◽  
...  
Keyword(s):  
Phase Transition ◽  
Visible Light ◽  
Band Gap ◽  
Conduction Band ◽  
Density Functional ◽  
Density Functional Theory Calculation ◽  
Pure Water ◽  
Volume Growth ◽  
Band Edge ◽  
Conduction Band Edge

Through phase transition-induced band edge engineering by dual doping with In and Mo, a new greenish BiVO4 (Bi1-XInXV1-XMoXO4) is developed that has a larger band gap energy than the usual yellow scheelite monoclinic BiVO4 as well as a higher (more negative) conduction band than H+/H2 potential [0 VRHE (reversible hydrogen electrode) at pH 7]. Hence, it can extract H2 from pure water by visible light-driven overall water splitting without using any sacrificial reagents. The density functional theory calculation indicates that In3+/Mo6+ dual doping triggers partial phase transformation from pure monoclinic BiVO4 to a mixture of monoclinic BiVO4 and tetragonal BiVO4, which sequentially leads to unit cell volume growth, compressive lattice strain increase, conduction band edge uplift, and band gap widening.

Band alignment at CdS/wide-band-gap Cu(In,Ga)Se2 hetero-junction by using PES/IPES

2005 ◽  
Vol 865 ◽  
Author(s):  
S.H. Kong ◽  
H. kashiwabara ◽  
K. Ohki ◽  
K. Itoh ◽  
T. Okuda ◽  
...  
Keyword(s):  
Band Gap ◽  
Conduction Band ◽  
Ion Beam ◽  
Wide Band ◽  
Valence Band Maximum ◽  
Conduction Band Minimum ◽  
Band Alignment ◽  
Interface Region ◽  
Photoemission Spectroscopy ◽  
Wide Gap

AbstractDirect characterization of band alignment at chemical bath deposition (CBD)-CdS/Cu0.93 (In1-xGax)Se2 has been carried out by photoemission spectroscopy (PES) and inverse photoemission spectroscopy (IPES). Ar ion beam etching at the condition of the low ion kinetic energy of 350 eV yields a removal of surface contamination as well as successful measurement of the intrinsic properties of each layer and the interfaces. Especially interior regions of the wide gap CIGS layers with a band gap of 1.4 ∼ 1.6 eV were successfully exposed. IPES spectra revealed that the conduction band offset (CBO) at the interface region of the wide gap CIGS with x = 0.60 and 0.75 was negative, where the conduction band minimum of CdS was lower than that of CIGS. It was also observed that the energy spacing between conduction band minimum (CBM) of CdS layer and valence band maximum (VBM) of Cu0.93(In0.25Ga0.75)Se2 layer at interface region was no wider than that of the interface over the Cu0.93(In0.60Ga0.40)Se2 layer.

Electronic Structure and Surface Properties of SrBi2Ta2O9 and Related Oxides

1997 ◽  
Vol 493 ◽  
Author(s):  
J Robertson ◽  
C W Chen
Keyword(s):  
Electronic Structure ◽  
Band Gap ◽  
Conduction Band ◽  
Tight Binding ◽  
Schottky Barriers ◽  
Band Edge ◽  
Conduction Band Edge ◽  
Edge States ◽  
Tight Binding Method ◽  
S States

ABSTRACTThe electronic structure of SrBi2Ta2O9 and related oxides such as SrBi2Nb2O9, Bi2WO6 and Bi3Ti4O12 have been calculated by the tight-binding method. In each case, the band gap is about 4.1 eV and the band edge states occur on the Bi-O layers and consist of mixed O p/Bi s states at the top of the valence band and Bi p states at the bottom of the conduction band. The main difference between the compounds is that Nb 5d and Ti 4d states in the Nb and Ti compounds lie lower than the Ta 6d states in the conduction band. The surface pinning levels are found to pin Schottky barriers 0.8 eV below the conduction band edge.

scholarly journals Влияние фтора на плотность состояний на границе раздела анодный оксидный слой/In-=SUB=-0.53-=/SUB=-Ga-=SUB=-0.47-=/SUB=-As

2021 ◽  
Vol 47 (10) ◽  
pp. 11
Author(s):  
М.С. Аксенов ◽  
Н.А. Валишева ◽  
А.П. Ковчавцев
Keyword(s):  
Fermi Level ◽  
Band Gap ◽  
Conduction Band ◽  
Annealing Temperature ◽  
State Density ◽  
The State ◽  
Conduction Band Bottom

It is shown that the fluorine-containing anodic layers on the n-In0.53Ga0.47As surface, in contrast to the anodic layers without fluorine, form a SiO2/InGaAs interface with an unpinned Fermi level, the state density on which decreases during annealing at a temperature of 300 °C to values (2-4) 1011 and (4-5) 1012 eV-1cm-2 near conduction band bottom and the band gap middle, respectively. An increase in the annealing temperature leads to a reverse increase in the state density (350 ºС) and pinning of the Fermi level (400 ºС).

scholarly journals Спектры пленок SmS в дальней и средней ИК областях

2019 ◽  
Vol 53 (11) ◽  
pp. 1544
Author(s):  
Ю.В. Улашкевич ◽  
В.В. Каминский ◽  
С.М. Соловьев ◽  
Н.В. Шаренкова
Keyword(s):  
Thin Films ◽  
Band Structure ◽  
Band Gap ◽  
Conduction Band ◽  
Donor Impurity ◽  
Basic Features

AbstractThe basic features of the band structure observed in bulk samples are retained in polycrystalline SmS thin films. Specifically, the bottom of the conduction band is formed from s -type states and there exist donor impurity levels in the band gap, at an energy of 0.04–0.065 eV below the bottom of the conduction band.

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