Revealing the Quantum-Confined Free Exciton A Anisotropic Emission in a CdS/CdS:SnS2 Superlattice Nanocone via Angle-Resolved Photoluminescence Spectroscopy

2022 ◽  
Author(s):  
Ye Tian ◽  
Yongyou Zhang ◽  
Hui Peng ◽  
Shangfei Yao ◽  
Tao Huang ◽  
...  
Keyword(s):  
Free Exciton ◽  
Photoluminescence Spectroscopy ◽  
Quantum Confined ◽  
Anisotropic Emission

scholarly journals Photoluminescence in quantum-confined SnO2 nanocrystals: Evidence of free exciton decay

2004 ◽  
Vol 84 (10) ◽  
pp. 1745-1747 ◽  
Author(s):  
E. J. H. Lee ◽  
C. Ribeiro ◽  
T. R. Giraldi ◽  
E. Longo ◽  
E. R. Leite ◽  
...  
Keyword(s):  
Free Exciton ◽  
Sno2 Nanocrystals ◽  
Exciton Decay ◽  
Quantum Confined

Spectroscopic Studies in InGaN Quantum Wells

1998 ◽  
Vol 537 ◽  
Author(s):  
S. E Chichibu ◽  
T. Sota ◽  
K. Wada ◽  
S. P DenBaars ◽  
S. Nakamura
Keyword(s):  
Absorption Spectrum ◽  
Quantum Wells ◽  
Stark Effect ◽  
Free Exciton ◽  
Stokes Shift ◽  
Molar Fraction ◽  
Potential Wells ◽  
Piezoelectric Polarization ◽  
Quantum Disk ◽  
Quantum Confined

AbstractFundamental electronic modulations in strained wurtzite If-nitride, in particular InxGa1-xN, quantum wells (QWs) were treated to explore the reason why practical InGaN devices emit bright luminescences in spite of the large threading dislocation (TD) density. The emission mechanisms were shown to vary depending on the well thickness L and InN molar fraction x. The electric field across the QW plane, F, which is a sum of the fields due to spontaneous and piezoelectric polarization and the pn junction field, causes the redshift of the ground state resonance energy through the quantum confined Stark effect (QCSE). The absorption spectrum is modulated by QCSE, quantum-confined Franz-Keldysh effect (QCFK), and Franz-Keldysh (FK) effect from the barrires when, for the first approximation, potential drop across the well (F/L) exceeds the valence band discontinuity, δEv. Under large F/L, holes are confined in the triangular potential well formed at one side of the well. This produces apparent Stokes-like shift in addition to the in-plane net Stokes shift on the absorption spectrum. The QCFK and FK further modulate the electronic structure of the wells with L greater than the three dimensional (3D) free exciton (FE) Bohr radius, aB. When F/L exceeds ΔEc, both electron (e) and hole (h) confined levels drop into the triangular potential wells at opposite sides of the wells, which reduces the wavefunction overlap. Doping of Si in the barriers partially screens the F resulting in a smaller Stokes-like shift, shorter recombination decay time, and higher emission efficiency. Finally, the use of InGaN was found to overcome the field-induced oscillator strength lowering due to the spontaneous and piezoelectric polarization. Effective in-plane localization of the QW excitons (confined excitons, or quantized excitons) in quantum disk (Q-disk) size potential minima, which are produced by nonrandom alloy potential fluctuation enhanced by the large bowing parameter and F, produces confined e-h pairs whose wavefunctions are still overlapped when L<aB. Their Coulomb interaction is more pronounced for F L<ΔEv.

scholarly journals Photoluminescence of 8H-SiC

2013 ◽  
Vol 740-742 ◽  
pp. 347-350 ◽  
Author(s):  
Anne Henry ◽  
Ivan G. Ivanov ◽  
Erik Janzén ◽  
Tomoaki Hatayama ◽  
Hiroshi Yano ◽  
...  
Keyword(s):  
Binding Energy ◽  
Low Temperature ◽  
Band Gap ◽  
Free Exciton ◽  
Photoluminescence Spectroscopy ◽  
Ionization Energies ◽  
Nitrogen Levels ◽  
Excitonic Band ◽  
Exciton Recombination

8H-SiC epilayers grown on small 8H-SiC Lely platelets are investigated optically using photoluminescence spectroscopy. At low temperature the near band gap emission detected in the 2.78 to 2.67 eV range contains sharp lines associated to nitrogen-bound-exciton recombination. Three different no-phonon lines are detected accompanied by their phonon replicas. Free-exciton replicas are also observed which allows the determination of the excitonic band gap. The binding energy of the bound excitons can thus be determined and the ionization energies of the three nitrogen levels in 8H-SiC are estimated and found to be rather shallow compared to the values for other hexagonal polytypes. Additional bound-exciton lines are observed when the experimental photoluminescence temperature is increased.

scholarly journals Spectroscopic Studies in InGaN Quantum Wells

1999 ◽  
Vol 4 (S1) ◽  
pp. 93-105 ◽  
Author(s):  
S. F. Chichibu ◽  
T. Sota ◽  
K. Wada ◽  
S. P. DenBaars ◽  
S. Nakamura
Keyword(s):  
Absorption Spectrum ◽  
Quantum Wells ◽  
Stark Effect ◽  
Free Exciton ◽  
Stokes Shift ◽  
Molar Fraction ◽  
Potential Wells ◽  
Piezoelectric Polarization ◽  
Quantum Disk ◽  
Quantum Confined

Fundamental electronic modulations in strained wurtzite III-nitride, in particular InxGa1−xN, quantum wells (QWs) were treated to explore the reason why practical InGaN devices emit bright luminescences in spite of the large threading dislocation (TD) density. The emission mechanisms were shown to vary depending on the well thickness L and InN molar fraction x. The electric field across the QW plane, F, which is a sum of the fields due to spontaneous and piezoelectric polarization and the pn junction field, causes the redshift of the ground state resonance energy through the quantum confined Stark effect (QCSE). The absorption spectrum is modulated by QCSE, quantum-confined Franz-Keldysh effect (QCFK), and Franz-Keldysh (FK) effect from the barrires when, for the first approximation, potential drop across the well (FL) exceeds the valence band discontinuity, EV. Under large FL, holes are confined in the triangular potential well formed at one side of the well. This produces apparent Stokes-like shift in addition to the in-plane net Stokes shift on the absorption spectrum. The QCFK and FK further modulate the electronic structure of the wells with L greater than the three dimensional (3D) free exciton (FE) Bohr radius, aB. When FL exceeds EC, both electron (e) and hole (h) confined levels drop into the triangular potential wells at opposite sides of the wells, which reduces the wavefunction overlap. Doping of Si in the barriers partially screens the F resulting in a smaller Stokes-like shift, shorter recombination decay time, and higher emission efficiency. Finally, the use of InGaN was found to overcome the field-induced oscillator strength lowering due to the spontaneous and piezoelectric polarization. Effective in-plane localization of the QW excitons (confined excitons, or quantized excitons) in quantum disk (Q-disk) size potential minima, which are produced by nonrandom alloy potential fluctuation enhanced by the large bowing parameter and F, produces confined e-h pairs whose wavefunctions are still overlapped when L<aB. Their Coulomb interaction is more pronounced for FL<EV.

The quantum confined Pockels effect in GaAs-based multi-quantum wells

1999 ◽  
Vol 09 (PR2) ◽  
pp. Pr2-37 ◽  
Author(s):  
O. Krebs ◽  
P. Voisin ◽  
D. Rondi ◽  
J. L. Gentner ◽  
L. Goldstein ◽  
...  
Keyword(s):  
Quantum Wells ◽  
Pockels Effect ◽  
Quantum Confined

Light-Induced Drift of Quantum-Confined Electrons in Semiconductor Heterostructures

1990 ◽  
Author(s):  
Mark I. Stockman ◽  
Lakshmi N. Pandey ◽  
Thomas F. George
Keyword(s):  
Semiconductor Heterostructures ◽  
Quantum Confined
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