Band Gaps, Effective Masses, and Band Offsets in Lattice Matched Heterojunctions

1991 ◽  
Vol 128 (2) ◽  
pp. K89-K93 ◽  
Author(s):  
L. Hrivnák
Keyword(s):  
Band Gaps ◽  
Band Offsets ◽  
Effective Masses ◽  
Lattice Matched

Band Gaps, Band‐Offsets, Disorder, Stability Region, and Point Defects in II‐IV‐N 2 Semiconductors

2019 ◽  
Vol 216 (15) ◽  
pp. 1800875 ◽  
Author(s):  
Sai Lyu ◽  
Dmitry Skachkov ◽  
Kathleen Kash ◽  
Eric W. Blanton ◽  
Walter R. L. Lambrecht
Keyword(s):  
Point Defects ◽  
Stability Region ◽  
Band Gaps ◽  
Band Offsets

scholarly journals First–Principles Investigation of the Structural, Elastic, Electronic, and Optical Properties of α– and β–SrZrS3: Implications for Photovoltaic Applications

Materials ◽  
2020 ◽  
Vol 13 (4) ◽  
pp. 978
Author(s):  
Henry Igwebuike Eya ◽  
Esidor Ntsoenzok ◽  
Nelson Y. Dzade
Keyword(s):  
Optical Properties ◽  
First Principles ◽  
Density Functional ◽  
Visible Region ◽  
Charge Carriers ◽  
Band Gaps ◽  
Strong Light ◽  
Electronic And Optical Properties ◽  
Optical Absorbance ◽  
Effective Masses

Transition metal perovskite chalcogenides are attractive solar absorber materials for renewable energy applications. Herein, we present the first–principles screened hybrid density functional theory analyses of the structural, elastic, electronic and optical properties of the two structure modifications of strontium zirconium sulfide (needle–like α–SrZrS3 and distorted β–SrZrS3 phases). Through the analysis of the predicted electronic structures, we show that both α– and β–SrZrS3 materials are direct band gaps absorbers, with calculated band gaps of 1.38, and 1.95 eV, respectively, in close agreement with estimates from diffuse–reflectance measurements. A strong light absorption in the visible region is predicted for the α– and β–SrZrS3, as reflected in their high optical absorbance (in the order of 105 cm−1), with the β–SrZrS3 phase showing stronger absorption than the α–SrZrS3 phase. We also report the first theoretical prediction of effective masses of photo-generated charge carriers in α– and β–SrZrS3 materials. Predicted small effective masses of holes and electrons at the valence, and conduction bands, respectively, point to high mobility (high conductivity) and low recombination rate of photo-generated charge carriers in α– and β–SrZrS3 materials, which are necessary for efficient photovoltaic conversion.

scholarly journals Verification of band offsets and electron effective masses in GaAsN/GaAs quantum wells: Spectroscopic experiment versus 10-band k·p modeling

2013 ◽  
Vol 113 (23) ◽  
pp. 233508 ◽  
Author(s):  
K. Ryczko ◽  
G. Sęk ◽  
P. Sitarek ◽  
A. Mika ◽  
J. Misiewicz ◽  
...  
Keyword(s):  
Quantum Wells ◽  
Band Offsets ◽  
Effective Masses ◽  
Experiment Versus

A thermoelastic model for strain effects on bandgaps and band offsets in heterostructure core/shell quantum dots

2019 ◽  
Vol 86 (3) ◽  
pp. 30401 ◽  
Author(s):  
Hilmi Ünlü
Keyword(s):  
Quantum Dots ◽  
Elastic Moduli ◽  
Band Gaps ◽  
Core Shell ◽  
Type Ii ◽  
Core Diameter ◽  
Band Offsets ◽  
Thermoelastic Model ◽  
Proposed Model ◽  
Core Band

A thermoelastic model is proposed to determine elastic strain effects on electronic properties of spherical Type I and Type II heterostructure core/shell quantum dots (QDs) as a function of dimensions of constituent semiconductors at any temperature. Proposed model takes into account the difference between lattice constants, linear expansion coefficients and anisotropy of elastic moduli (Young's modulus and Poisson's ratio) of constituent semiconductors, respectively. In analogous to lattice mismatch, we introduce so called the elastic anisotropy mismatch in heterostructures. Compressive strain acting on core (shell) side of heterointerfaces in CdSe/CdS, CdSe/ZnS, and ZnSe/ZnS QDs increases (decreases) as shell diameter is increased, which causes increase (decrease) in core bandgap as sell (core) diameter is increased in these nanostructures. Furthermore, there is a parabolic increase in conduction band offsets and core bandgaps in CdSe/CdS, CdSe/ZnS, and ZnSe/ZnS QDs and decrease in conduction band offset and core bandgap of ZnSe/CdS QD as core (shell) diameter increases for fixed shell (core) diameter. Comparison shows that using isotropic elastic moduli in determining band offsets and core band gaps gives better agreement with experiment than anisotropic elastic moduli for core bandgaps of CdSe/CdS, CdSe/ZnS, ZnSe/ZnS, and ZnSe/CdS core/shell QDs. Furthermore, we also show that the strain-modified two band effective mass approximation can be used to determine band offsets by using measured core band gaps in core/shell heterostructure QDs with Type II interface band alignment. Excellent agreement between predicted and measured core bandgaps in CdSe and ZnSe based core/shell QDs suggests that proposed model can be a good design tool for process simulation of core/shell heterostructure QDs.

Electronic structures of Zn1-xGaxO1-xNx and band offsets of ZnO/Zn1-xGaxO1-xNx heterojunction across the entire concentration range from first principles

2021 ◽  
Author(s):  
Tianjiao Li ◽  
Xiaojie Liu ◽  
Yin Wang ◽  
Ronggen Cao ◽  
Haitao Yin
Keyword(s):  
First Principles ◽  
Electronic Structures ◽  
Band Gaps ◽  
Entire Concentration Range ◽  
Band Offsets ◽  
Optoelectronics Devices

Band offsets at the heterointerfaces play a key role in defining the functionality of optoelectronics devices. In this work, the band gaps of wurtzite Zn1-xGaxO1-xNx alloys and the band offsets...

Electrons in a square lattice

2021 ◽  
pp. 352-362
Author(s):  
Geoffrey Brooker
Keyword(s):  
Periodic Potential ◽  
Band Gaps ◽  
Three Dimensions ◽  
Square Lattice ◽  
One Dimension ◽  
Two Dimensional ◽  
Effective Masses ◽  
Overlapping Bands

“Electrons in a square lattice” describes how a two-dimensional square lattice gives a helpful case intermediate between one dimension and the complication of three dimensions. The “empty lattice” divides up k-space into Brillouin zones in anticipation of a periodic potential whose period is given but whose magnitude is at this stage zero. A wooden model uses height to represent energy. Rearranging the model's pieces into the reduced-zone scheme displays how electrons can have surprising energy–wavevector relations, including overlapping bands, anisotropic effective masses, and indirect band gaps.

Improved tight-binding parameters of III-V semiconductor alloys and their application to type-II superlattices

2021 ◽  
Author(s):  
Akitaka Sawamura ◽  
Takashi Kato ◽  
Satofumi SOUMA
Keyword(s):  
Absorption Coefficient ◽  
Energy Levels ◽  
Tight Binding ◽  
Band Gaps ◽  
Type Ii ◽  
Binding Parameters ◽  
Semiconductor Alloys ◽  
Effective Masses ◽  
Type Ii Superlattices ◽  
Ternary Semiconductor

Abstract A simple tight-binding method for ternary semiconductor alloys is generalized to calculate the properties of the semiconductor alloys accurately. Specifically independently adjustable parameters, which represent compositional disorder, are incorporated in all the ternary tight-binding parameters. Energy levels and effective masses agree well with the reference values only by the proposed method. We have applied the method to calculate the band gaps and a spectrum of the absorption coefficient of (InAs)/(GaInSb) type-II superlattices. The calculated band-gaps agree well with the experimental ones and we could well reproduce the shape of the absorption coefficient spectrum calculated by an empirical pseudopotential scheme.

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