Free and Bound Excitons in GaN Epitaxial Films

1996 ◽  
Vol 449 ◽  
Author(s):  
B.K. Meyer
Keyword(s):  
Thermal Activation ◽  
Chemical Nature ◽  
Epitaxial Films ◽  
Binding Energies ◽  
Temperature Dependent ◽  
Neutral Donor ◽  
Exciton Localization ◽  
Sapphire Substrates ◽  
Shallow Donors ◽  
Shallow Impurities

ABSTRACTWe report on photoluminescence experiments on hexagonal GaN epitaxial films grown on 6H-SiC and sapphire substrates by organo-metallic and hydide vapor phase epitaxy. At low temperatures we observe free and neutral donor bound exciton transitions which allow to establish properties of the free excitons and localisation energies of the bound excitons involving different shallow donors. From temperature dependent luminescence experiments thermal activation energies are determined which measure the exciton localization and donor binding energies. The localization energies of the excitons scale with the respective donor binding energies (Haynes rule). The inter-impurity transitions of neutral donors are observed in fourier transform infra-red absorption. Three shallow donors with binding energies of 34.7 meV, 55 meV and 58 meV can be seen. We present evidence for the chemical nature of the shallow impurities.

Temperature Dependence of Bound Exciton Emissions in GaN

1998 ◽  
Vol 537 ◽  
Author(s):  
D. G. Chtchekine ◽  
G. D. Gilliland ◽  
Z. C. Feng ◽  
S. J. Chua ◽  
D. J. Wolford ◽  
...  
Keyword(s):  
Activation Energy ◽  
Thermal Activation ◽  
Free Exciton ◽  
Shallow Donor ◽  
Temperature Dependent ◽  
Exciton Dissociation ◽  
Localization Energy ◽  
Exciton Localization ◽  
Neutral Acceptor ◽  
Temperature Dependent Photoluminescence

AbstractThe dissociation channels of two prominent bound exciton complexes in wurtzite GaN thin films are determined via an extensive temperature dependent photoluminescence study. The shallow donor bound exciton dissociation at low temperatures (T ≤ 50 K) is found to be dominated by the release of a free exciton with thermal activation energy consistent with the exciton localization energy. At higher temperatures a second dissociation channel with activation energy EA = 28 ± 2 meV is observed. The dissociation of a bound exciton complex with exciton localization energy Exloc = 11.7 meV is also dominated by the release of a free exciton. In contrast to previous studies evidence is presented against the hypothesis of this emission being due to the exciton bound to an ionized donor. We find that it originates most likely from an exciton bound to a neutral acceptor.

Light- and Heavy-Hole Bound Exciton Transitions and Free to Bound Transitions in GaxAl1-xAs/GaAs Quantum Wells

1989 ◽  
Vol 163 ◽  
Author(s):  
Donald C. Reynolds ◽  
K.K. Bajaj
Keyword(s):  
Quantum Wells ◽  
Heavy Hole ◽  
Free Exciton ◽  
Light Hole ◽  
Binding Energies ◽  
Temperature Dependent ◽  
Neutral Donor ◽  
Free Hole ◽  
Quantum Well Structures ◽  
Exciton Transitions

AbstractExcitons bound to neutral donors in AlxGa1-xAs/GaAs quantum wells were observed by high resolution resonant excitation photoluminescence, and temperature dependent photoluminescence measurements. Changes in the binding energy of excitons are observed when the donors are located in the center of the well, at the edge of the well, or in the center of the barrier. The variations in these binding energies are reported as a function of well size from 75–350Å. The binding energies increased as the well size was reduced to about 100Å, with further reductions in well size they decreased.Light-hole free excitons bound to neutral donors were observed in AlxGa1-xAs/GaAs quantum wells. The transitions were observed, using selective excitation photoluminescence spectroscopy, in the energy region between the light-hole and heavy-hole free exciton transitions where no other intrinsic transitions exist. The neutral donor-bound heavy-hole free-exciton transitions were also observed when the light-hole bound exciton transitions were observed. Quantum well structures which showed no evidence of a heavy-hole donor bound exciton also showed no evidence of a light-hole donor bound exciton.Free to bound transitions, free hole to bound electron, have also been observed in the AlxGa1-xAs/GaAs quantum wells. The diamagnetic shift of these transitions was used to distinguish them from excitonic transitions.

Temperature Dependent Hall Measurements on PLD Thin Films

2006 ◽  
Vol 957 ◽  
Author(s):  
Holger von Wenckstern ◽  
Matthias Brandt ◽  
Gregor Zimmermann ◽  
Jörg Lenzner ◽  
Holger Hochmuth ◽  
...  
Keyword(s):  
Thin Films ◽  
Oxygen Partial Pressure ◽  
Partial Pressure ◽  
Thermal Activation ◽  
Pulsed Laser ◽  
Thermal Activation Energy ◽  
Laser Deposition ◽  
Temperature Dependent ◽  
Sapphire Substrates ◽  
Partial Pressures

ABSTRACTThe electrical properties of epitaxial ZnO thin films grown on sapphire substrates by pulsed laser deposition were investigated by temperature dependent Hall measurents. The thin films investigated were grown at different oxygen partial pressures ranging from 10-2 mbar to 1 mbar. The formation of a degenerate layer, determining the low temperature Hall data, depends on the oxygen partial pressure applied during growth. Further, the formation of such a layer can be correlated to the grain size of the samples. The thermal activation energy of dominant donors decreases in tendency with increasing oxygen partial pressure p(O2); it is about 100 meV for p(O2) ≤ 3 × 10-2 mbar and about 30 meV for p(O2) ≥ 0.1 mar. The concentration of donors and compensating acceptors increases with increasing p(O2).

Photoluminescence and acceptor level state of p-type nitrogen-doped MgZnO films

2007 ◽  
Vol 22 (10) ◽  
pp. 2791-2795 ◽  
Author(s):  
Z.P. Wei ◽  
B. Yao ◽  
X.H. Wang ◽  
Z.Z. Zhang ◽  
Y.M. Lu ◽  
...  
Keyword(s):  
Energy Shift ◽  
Binding Energies ◽  
Temperature Dependent ◽  
Neutral Donor ◽  
Exciton Emission ◽  
Nitrogen Doped ◽  
Acceptor Energy Level ◽  
P Type ◽  
Type Conduction ◽  
Neutral Acceptor

A wurtzite nitrogen-doped MgZnO (MgZnO:N) film was grown by plasma-assisted molecular-beam epitaxy (PAMBE) on c-plane sapphire using radical NO as oxygen source and nitrogen dopant. The as-grown film shows n-type conduction at room temperature, but transforms into p-type conduction after annealed. Photoluminescence (PL) spectrum measured at 80 K is dominated by neutral donor-bound exciton emission (D0X) located at 3.522 eV for the n-type MgZnO:N film, but by neutral acceptor-bound exciton emission (A0X) located at 3.515 eV for the p-type MgZnO:N film. By fitting exciton emission intensity of temperature-dependent PL spectra, the binding energies of the D0X and A0X were estimated to be 32 and 43 meV, respectively. Based on the energy shift of exciton emission, the band gap of the MgZnO:N film is estimated to be 3.613 eV, which is 179 meV larger than that of ZnO. Using the Haynes rule, the acceptor energy level of the MgZnO:N film was evaluated to be about 176 meV above the valence band.

scholarly journals Temperature Dependence of Bound Exciton Emissions in GaN

1999 ◽  
Vol 4 (S1) ◽  
pp. 733-738 ◽  
Author(s):  
D. G. Chtchekine ◽  
G. D. Gilliland ◽  
Z. C. Feng ◽  
S. J. Chua ◽  
D. J. Wolford ◽  
...  
Keyword(s):  
Activation Energy ◽  
Thermal Activation ◽  
Free Exciton ◽  
Shallow Donor ◽  
Temperature Dependent ◽  
Exciton Dissociation ◽  
Localization Energy ◽  
Exciton Localization ◽  
Neutral Acceptor ◽  
Temperature Dependent Photoluminescence

The dissociation channels of two prominent bound exciton complexes in wurtzite GaN thin films are determined via an extensive temperature dependent photoluminescence study. The shallow donor bound exciton dissociation at low temperatures (T ≤ 50 K) is found to be dominated by the release of a free exciton with thermal activation energy consistent with the exciton localization energy. At higher temperatures a second dissociation channel with activation energy EA = 28 ± 2 meV is observed. The dissociation of a bound exciton complex with exciton localization energy EXloc = 11.7 meV is also dominated by the release of a free exciton. In contrast to previous studies evidence is presented against the hypothesis of this emission being due to the exciton bound to an ionized donor. We find that it originates most likely from an exciton bound to a neutral acceptor.

Temperature-dependent Raman and photoluminescence of β-Ga2O3 doped with shallow donors and deep acceptors impurities

2021 ◽  
pp. 160665
Author(s):  
Kun Zhang ◽  
Zongwei Xu ◽  
Junlei Zhao ◽  
Hong Wang ◽  
Jianmin Hao ◽  
...  
Keyword(s):  
Temperature Dependent ◽  
Shallow Donors

Chemical lift-off of GaN epitaxial films grown on c-sapphire substrates with CrN buffer layers

2008 ◽  
Vol 5 (6) ◽  
pp. 1659-1661 ◽  
Author(s):  
H. Goto ◽  
S. W. Lee ◽  
H. J. Lee ◽  
Hyo-Jong Lee ◽  
J. S. Ha ◽  
...  
Keyword(s):  
Epitaxial Films ◽  
Buffer Layers ◽  
Sapphire Substrates ◽  
Lift Off

Halide Vapor Phase Epitaxy α‐ and ε‐Ga 2 O 3 Epitaxial Films Grown on Patterned Sapphire Substrates

2020 ◽  
Vol 217 (14) ◽  
pp. 1900892 ◽  
Author(s):  
Sevastian Shapenkov ◽  
Oleg Vyvenko ◽  
Evgeny Ubyivovk ◽  
Oleg Medvedev ◽  
Georgiy Varygin ◽  
...  
Keyword(s):  
Vapor Phase ◽  
Epitaxial Films ◽  
Vapor Phase Epitaxy ◽  
Sapphire Substrates ◽  
Patterned Sapphire Substrates

scholarly journals Photoluminescence excitation spectroscopy of GaN thin layers as a function of temperature

1997 ◽  
Vol 2 ◽  
Author(s):  
C. Guénaud ◽  
E. Deleporte ◽  
M. Voos ◽  
C. Delalande ◽  
B. Beaumont ◽  
...  
Keyword(s):  
Optical Properties ◽  
Low Temperature ◽  
Thin Layers ◽  
Photoluminescence Excitation ◽  
Temperature Dependent ◽  
Electron Hole ◽  
Yellow Band ◽  
Neutral Donor ◽  
Photoluminescence Line ◽  
Temperature Dependent Photoluminescence

We report on photoluminescence and photoluminescence excitation experiments performed on hexagonal GaN layers grown on a Sapphire substrate. Information about extrinsic and intrinsic optical properties have been obtained. We show that, at low temperature, the fundamental A excitons are preferentially involved in the relaxation towards the neutral donor bound exciton photoluminescence line, while electron-hole pairs rather participate in the relaxation towards D0−A0 emission and the yellow band. The relaxation from the A exciton towards the yellow band and D0−A0 emission is made easier by temperature. The band structure of the GaN layers has been determined from temperature dependent photoluminescence excitation spectroscopy: A and C excitons and A continuum band gap have been identified up to 210K.

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