Low Temperature Photoluminescence Studies of Narrow Bandgap Gaassbn Quantum Wells on GaAs

2002 ◽  
Vol 744 ◽  
Author(s):  
K.E. Waldrip ◽  
E.D. Jones ◽  
N.A. Modine ◽  
F. Jalali ◽  
J.F. Klem ◽  
...  
Keyword(s):  
Low Temperature ◽  
Quantum Wells ◽  
Band Gap ◽  
First Principles ◽  
Structure Calculation ◽  
Ex Situ ◽  
Band Structure Calculation ◽  
Narrow Bandgap ◽  
Order Of Magnitude ◽  
Photoluminescence Studies

We present low-temperature (T = 4K) photoluminescence studies of the effect of adding nitrogen to 6-nm-wide single-strained GaAsSb quantum wells on GaAs. The samples were grown by both MBE and MOCVD tech-niques. The nominal Sb concentration is about 30%. Adding about 1 to 2% N drastically reduced the bandgap energies from 1 to 0.75 eV, or 1.20 to 1.64 μm. Upon performing ex situ rapid thermal anneals, 825°C for 10s, the band gap energies as well as the photoluminescence intensities increased. The intensities increased by an order of magnitude for the annealed samples and the band gap energies increased by about 50 - 100 meV, depending on growth temperatures. The photoluminescence linewidths tended to decrease upon annealing. Preliminary results of a first-principles band structure calculation for the GaAsSbN system are also presented.

scholarly journals Influence of Secondary Phases in Kesterite-Cu2ZnSnS4Absorber Material Based on the First Principles Calculation

2015 ◽  
Vol 2015 ◽  
pp. 1-6 ◽  
Author(s):  
Wujisiguleng Bao ◽  
Masaya Ichimura
Keyword(s):  
Band Structure ◽  
Band Gap ◽  
First Principles ◽  
Structure Calculation ◽  
First Principles Calculation ◽  
Band Structure Calculation ◽  
Type I ◽  
Secondary Phases ◽  
Recombination Site ◽  
Absorber Material

The influence of secondary phases of ZnS and Cu2SnS3(CTS) in Cu2ZnSnS4(CZTS) absorber material has been studied by calculating the band offsets at the CTS/CZTS/ZnS multilayer heterojunction interfaces on the basis of the first principles band structure calculation. The ZnS/CZTS heterointerface is of type I and since ZnS has a larger band gap than that of CZTS, the ZnS phase in CZTS is predicted to be resistive barriers for carriers. The CTS/CZTS heterointerface is of type I; that is, the band gap of CTS is located within the band gap of CZTS. Therefore, the CTS phase will act as a recombination site in CZTS.

AB-INITIO BAND STRUCTURE CALCULATION FOR MAGNETIC MULTILAYERS

1993 ◽  
Vol 07 (01n03) ◽  
pp. 456-459 ◽  
Author(s):  
J. STICHT ◽  
F. HERMAN ◽  
J. KÜBLER
Keyword(s):  
Magnetic Properties ◽  
Band Structure ◽  
Total Energy ◽  
Ab Initio ◽  
Coupling Strength ◽  
First Principles ◽  
Exchange Coupling ◽  
Magnetic Multilayers ◽  
Structure Calculation ◽  
Band Structure Calculation

The magnetic properties of magnetic multilayers are studied using first principles total energy calculations. In this paper we present our results for bcc Fe multilayers with a (001) stacking direction. Using Nb as a spacer material we find an oscillating exchange coupling with a period of about 4.6 Å( ≈3 Nb monolayers). A detailed study of the magetic moments in the Nb spacer is given. Furthermore we discuss the dependence of the exchange coupling strength as a function of the thickness of the Fe slabs.

FIRST-PRINCIPLES STUDIES ON THE ELECTRONIC STRUCTURE OF BaCuSi2O6

2010 ◽  
Vol 24 (14) ◽  
pp. 2205-2210
Author(s):  
T. JEONG
Keyword(s):  
Electronic Structure ◽  
First Principles ◽  
Density Functional ◽  
Local Density ◽  
Structure Calculation ◽  
Band Structure Calculation ◽  
Density Approximation ◽  
Structure And Properties ◽  
Functional Theory ◽  
The Density Functional Theory

The electronic properties of BaCuSi 2 O 6 are studied by band structure calculation based on the density functional theory within local density approximation. We find that the electronic structure and properties are dominated by the layered character of the crystal structure arising from the in plane Cu 3d and O 2p electron interactions.

MID-IR Photodetectors Based on InAs/InGaSb Type-II Quantum Wells

1997 ◽  
Vol 484 ◽  
Author(s):  
G. J. Brown ◽  
M. Ahoujja ◽  
F. Szmulowicz ◽  
W. C. Mitchel ◽  
C. H. Lin
Keyword(s):  
Quantum Wells ◽  
Band Gap ◽  
Energy Band ◽  
Structural Parameters ◽  
X Ray Diffraction ◽  
Energy Band Gap ◽  
X Ray ◽  
Hall Measurements ◽  
Before And After ◽  
Order Of Magnitude

AbstractWe report on the growth and characterization of InAs/InxGal..Sb strained-layer superlattices (SLS) designed with a photoresponse cut-off wavelength of IOlim. The structural parameters, layer thicknesses and compositions, were chosen to optimize the infrared absorption for a superlattice with an energy band gap of 120 meV. The energy band structure and optimized absorption coefficient were determined with an 8×8 envelope function approximation model. The superlattices were grown by molecular beam epitaxy and were comprised of 100 periods of 43.6Å InAs and 17.2Å In.23Ga.77Sb lattice-matched to the GaSb substrates. In order to reduce the background carrier concentrations in this material, superlattices grown with different substrate temperatures were compared before and after annealing. This set of superlattice materials was characterized using x-ray diffraction, photoresponse and Hall measurements. The measured photoresponse cut-off energies of 116 ± 6 meV is in good agreement with the predicted energy band gap for the superlattice as designed. The intensity of the measured mid-infrared photoresponse was found to improve by an order of magnitude for the superlattice grown at the lower substrate temperature and then annealed at 520 °C for 10 minutes. However, the x-ray diffraction spectra were very similar before and after annealing. The temperature dependent Hall measurements at low temperatures (<25K) were dominated by holes with quasi two-dimensional behavior. An admirably low background carrier concentration of 1×1012 cm−2 was measured at low temperature.

Band structure calculation of InGaAsN//GaAs, InGaAsN//GaAsP//GaAs and InGaAsN//InGaAsP//InP strained quantum wells

2004 ◽  
Vol 151 (5) ◽  
pp. 402-406 ◽  
Author(s):  
H. Carrère ◽  
T. Amand ◽  
J. Barrau ◽  
X. Marie ◽  
J.-C. Harmand ◽  
...  
Keyword(s):  
Band Structure ◽  
Quantum Wells ◽  
Structure Calculation ◽  
Band Structure Calculation ◽  
Strained Quantum Wells
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