Erbium energy levels relative to the band gap of gadolinium oxide

AbstractDefect energy levels of oxygen vacancies in various high K oxides HfO2, ZrO2, La2O3 and SrTiO3 have been calculated using methods which give the correct band gap, such as the screened exchange and weighted density approximation.

Download Full-text

Electronic Structure for a Distorted Chain

Canadian Journal of Physics ◽

10.1139/p72-149 ◽

1972 ◽

Vol 50 (11) ◽

pp. 1078-1081

Author(s):

T. C. Wong ◽

B. Y. Tong

Keyword(s):

Electronic Structure ◽

Band Gap ◽

Density Of States ◽

Energy Levels ◽

Linear Chain ◽

Integrated Density Of States ◽

Counting Method ◽

Model Liquid ◽

Impurity Atoms ◽

Specific Manner

A linear chain with impurities randomly distributed along it is studied by means of the node counting method. The host atoms as well as the impurity atoms are represented by negative δ-function potentials with different strengths. The solvent atoms are distorted in a specific manner about each impurity atom. The integrated density of states are calculated near a band gap for different impurity concentrations and for various degrees of distortion. It was found that without distortion the gap remains practically structureless, whereas with distortion the energy levels diffuse into the gap. The results are qualitatively similar to that of a model liquid.

Download Full-text

Analysis of electronic structure and optical properties of N-doped SiO2 based on DFT calculations

Modern Physics Letters B ◽

10.1142/s0217984915501006 ◽

2015 ◽

Vol 29 (19) ◽

pp. 1550100 ◽

Cited By ~ 1

Author(s):

Sui-Shuan Zhang ◽

Zong-Yan Zhao ◽

Pei-Zhi Yang

Keyword(s):

Optical Properties ◽

Electronic Structure ◽

Band Gap ◽

Impurity Concentration ◽

Nitrogen Concentration ◽

Energy Levels ◽

Optical Parameter ◽

Doping Effects ◽

N Doping ◽

The Relationship

The crystal structure, electronic structure and optical properties of N-doped [Formula: see text] with different N impurity concentrations were calculated by density function theory within GGA[Formula: see text]+[Formula: see text]U method. The crystal distortion, impurity formation energy, band gap, band width and optical parameter of N-doped [Formula: see text] are closely related with N impurity concentration. Based on the calculated results, there are three new impurity energy levels emerging in the band gap of N-doped [Formula: see text], which determine the electronic structure and optical properties. The variations of optical properties induced by N doping are predominately determined by the unsaturated impurity states, which are more obvious at higher N impurity concentration. In addition, all the doping effects of N in both [Formula: see text]-quartz [Formula: see text] and [Formula: see text]-quartz [Formula: see text] are very similar. According to these findings, one could understand the relationship between nitrogen concentration and optical parameter of [Formula: see text] materials, and design new optoelectrionic Si–O–N compounds.

Download Full-text

Deep Levels in Superlattices

MRS Proceedings ◽

10.1557/proc-163-349 ◽

1989 ◽

Vol 163 ◽

Cited By ~ 3

Author(s):

John D. Dow ◽

Shang Yuan Ren ◽

Jun Shen ◽

Min-Hsiung Tsai

Keyword(s):

Band Gap ◽

Quantum Confinement ◽

Deep Level ◽

Energy Levels ◽

Deep Trap ◽

Shallow Donor ◽

Deep Levels ◽

Band Gap Engineering ◽

Substitutional Impurities ◽

Superlattice Period

AbstractThe physics of deep levels in semiconductors is reviewed, with emphasis on the fact that all substitutional impurities produce deep levels - some of which may not lie within the fundamental band gap. The character of a dopant changes when one of the deep levels moves into or out of the fundamental gap in response to a perturbation such as pressure or change of host composition. For example, Si on a Ga site in GaAs is a shallow donor, but becomes a deep trap for x>0.3 in AℓxGa1-xAs. Such shallow-deep transitions can be induced in superlattices by changing the period-widths and quantum confinement. A good rule of thumb for deep levels in superlattices is that the energy levels with respect to vacuum are relatively insensitive (on a >0.1 eV scale) to superlattice period-widths, but that the band edges of the superlattices are sensitive to changes of period. Hence the deep level positions relative to the band edges are sensitive to the period-widths, and shallow-deep transitions can be induced by band-gap engineering the superlattice periods.

Download Full-text

A Tale of Current and Voltage: Interplay of Band Gap and Energy Levels of Conjugated Polymers in Bulk Heterojunction Solar Cells

Macromolecules ◽

10.1021/ma101646r ◽

2010 ◽

Vol 43 (24) ◽

pp. 10390-10396 ◽

Cited By ~ 54

Author(s):

Huaxing Zhou ◽

Liqiang Yang ◽

Shubin Liu ◽

Wei You

Keyword(s):

Solar Cells ◽

Conjugated Polymers ◽

Band Gap ◽

Bulk Heterojunction ◽

Energy Levels ◽

Heterojunction Solar Cells ◽

Bulk Heterojunction Solar Cells

Download Full-text

Direct band gap energies and energy levels of Co2+ ion in ternary compound semiconductors by photoacoustic technique

Solid State Communications ◽

10.1016/0038-1098(88)90257-8 ◽

1988 ◽

Vol 68 (1) ◽

pp. 123-126 ◽

Cited By ~ 4

Author(s):

Jae-Eun Kim ◽

Hae Young Park ◽

Chang-Dae Kim ◽

Hyung-Gon Kim ◽

Wha-Tek Kim ◽

...

Keyword(s):

Band Gap ◽

Ternary Compound ◽

Energy Levels ◽

Compound Semiconductors ◽

Photoacoustic Technique ◽

Direct Band Gap ◽

Direct Band

Download Full-text

Low band gap copolymers based on thiophene and quinoxaline: Their electronic energy levels and photovoltaic application

Journal of Polymer Science Part A Polymer Chemistry ◽

10.1002/pola.23419 ◽

2009 ◽

Vol 47 (13) ◽

pp. 3399-3408 ◽

Cited By ~ 32

Author(s):

Qiang Peng ◽

Jun Xu ◽

Wenxu Zheng

Keyword(s):

Band Gap ◽

Energy Levels ◽

Electronic Energy ◽

Low Band Gap ◽

Photovoltaic Application ◽

Electronic Energy Levels

Download Full-text

The Effect of Defect Disorder on the Electronic Structure of Rutile TiO2-x

Defect and Diffusion Forum ◽

10.4028/www.scientific.net/ddf.251-252.1 ◽

2006 ◽

Vol 251-252 ◽

pp. 1-12 ◽

Cited By ~ 4

Author(s):

Faruque M. Hossain ◽

Graeme E. Murch ◽

L. Sheppard ◽

Janusz Nowotny

Keyword(s):

Electronic Structure ◽

Band Gap ◽

Point Defects ◽

Density Functional ◽

Defect Formation ◽

Energy Levels ◽

Defect Energy ◽

Defect Disorder ◽

Effect Of Oxygen ◽

Formation Energies

The purpose of this work is to study the effect of bulk point defects on the electronic structure of rutile TiO2. The paper is focused on the effect of oxygen nonstoichiometry in the form of oxygen vacancies, Ti interstitials and Ti vacancies and related defect disorder on the band gap width and on the local energy levels inside the band gap. Ab initio density functional theory is used to calculate the formation energies of such intrinsic defects and to detect the positions of these defect induced energy levels in order to visualize the tendency of forming local mid-gap bands. Apart from the formation energy of the Ti vacancies (where experimental data do not exist) our calculated results of the defect formation energies are in fair agreement with the experimental results and the defect energy levels consistently support the experimental observations. The calculated results indicate that the exact position of defect energy levels depends on the estimated band gap and also the charge state of the point defects of TiO2.

Download Full-text