Time-Resolved Photoluminescence of GaN / Ga0.93Al0 .07N Quantum Wells

1997 ◽  
Vol 482 ◽  
Author(s):  
P. Lefebvre ◽  
J. Allègre ◽  
B. Gil ◽  
A. Kavokine ◽  
H. Mathieu ◽  
...  
Keyword(s):  
Quantum Wells ◽  
Radiative Lifetime ◽  
Temperature Limit ◽  
Multiple Quantum ◽  
Carrier Localization ◽  
Substantial Variation ◽  
Time Resolved ◽  
Potential Fluctuations ◽  
Alloy Disorder ◽  
Time Resolved Photoluminescence

AbstractThe recombination dynamics of excitons in GaN / Ga0.93Al0.07N multiple quantum wells is studied versus lattice temperature. The average decay time of photoluminescence measured at 8K is of ∼330 ps, with a substantial variation of times within the emission line. This is interpreted in terms of carrier localization due to alloy disorder and to well width and depth variations. The radiative lifetime τr of excitons in the wells is found to increase linearly with temperature, with ∂τr / ∂T = 20.5 ± 0.7 ps.K−1. The radiative lifetime of free excitons in the low-temperature limit is deduced to be 2.4 ps, consistent with a longitudinal-transverse splitting ћωLT in GaN of 0.6 meV, in excellent agreement with recent estimations. The ratio of the lifetimes of localized and free excitons is found coherent with the picture of electrons and holes independently localized on short-range defects, instead of excitons localized as a whole on long-range potential fluctuations.

Optical Transitions and Recombination Lifetimes in GaN and InGaN Epilayers, and InGaN/GaN and GaN/AlGaN Multiple Quantum Wells

1996 ◽  
Vol 449 ◽  
Author(s):  
M. Smith ◽  
J. Y. Lin ◽  
H. X. Jiang ◽  
A. Khan ◽  
Q. Chen ◽  
...  
Keyword(s):  
Quantum Wells ◽  
Chemical Vapor ◽  
Multiple Quantum Wells ◽  
Organic Chemical ◽  
Multiple Quantum ◽  
Optical Transitions ◽  
Time Resolved ◽  
Metal Organic ◽  
Recombination Lifetimes ◽  
Time Resolved Photoluminescence

ABSTRACTTime-resolved photoluminescence (PL) has been employed to study the optical transitions and their dynamical processes in GaN and InxGa1-xN epilayers, and GaN/GaN and GaN/ALxGa1-xN multiple quantum wells (MQW). We compare the results from both metal-organic chemical vapor deposition (MOCVD) and molecular beam epitaxy (MBE) grown samples. In addition, results are also compared with GaAs/ALxGa1-xAs MQW. It was found for all samples that the low temperature emission lines were dominated by radiative recombination transitions of either localized or free excitons, which demonstrates the high quality and purity of these III-nitride materials.

Optical Properties of Ingan/GaN Multi Quantum Well Structures

1997 ◽  
Vol 482 ◽  
Author(s):  
J. P. Bergman ◽  
N. Saksulv ◽  
J. Dalfors ◽  
P. O. Holtz ◽  
B. Monemar ◽  
...  
Keyword(s):  
Quantum Wells ◽  
Multiple Quantum ◽  
Recombination Rates ◽  
Energy Position ◽  
Electron Hole ◽  
Time Resolved ◽  
Quantum Well Structures ◽  
Lower Energy Band ◽  
Time Resolved Photoluminescence ◽  
Multi Quantum Well

AbstractA set of GaN/InGaN multiple quantum wells (QWs) with well thickness 30 Å and barrier thickness 60 Å were grown by MOCVD on sapphire substrates. The n-type Si doping of the InGaN QWs was varied, in order to produce a different electron concentration in the QWs for the different samples. Optical spectra were obtained by time resolved photoluminescence spectroscopy. The data show weak excitonic spectra from the QWs as well as a broad deeper emission with a much stronger intensity. The spectral shape becomes narrower and the energy position shifts to higher energies with increasing doping. The two different emissions are not easily separated in CW or time integrated spectra, but are clearly observed in a time resolved spectral measurement due to their different recombination rates. The deeper emission has a long and non-exponential decay, with an average decay time in the order of several hundred nanoseconds. The higher energy exciton emission has a much faster decay of about 1 ns. The lower energy band is tentatively explained as due to separately localized electron-hole (e-h) pairs in the QW.

scholarly journals Time-resolved photoluminescence of quaternary AlInGaN-based multiple quantum wells

2002 ◽  
Vol 80 (21) ◽  
pp. 3943-3945 ◽  
Author(s):  
Mee-Yi Ryu ◽  
C. Q. Chen ◽  
E. Kuokstis ◽  
J. W. Yang ◽  
G. Simin ◽  
...  
Keyword(s):  
Quantum Wells ◽  
Multiple Quantum Wells ◽  
Multiple Quantum ◽  
Time Resolved ◽  
Time Resolved Photoluminescence

scholarly journals Room-Temperature Time–Resolved Photoluminescence Studies of UV Emission from GaN/AlN Quantum Wells

2002 ◽  
Vol 743 ◽  
Author(s):  
Madalina Furis ◽  
Fei Chen ◽  
Alexander N. Cartwright ◽  
Hong Wu ◽  
William J. Schaff
Keyword(s):  
Quantum Wells ◽  
Room Temperature ◽  
Spatial Separation ◽  
Multiple Quantum ◽  
Carrier Injection ◽  
Time Resolved ◽  
Uv Emission ◽  
Time Resolved Photoluminescence ◽  
Temperature Time ◽  
Ir Light

ABSTRACTRoom temperature time-resolved photoluminescence (TRPL) studies of multiple quantum well (MQW) structures of the binaries GaN and AlN grown by molecular beam epitaxy are reported. The eventual application of these structures is for GaN intersubband IR light emitters. However, as an initial study, the structures are evaluated at UV to investigate materials parameters relevant to IR light emission. The nominally 0.9, 1.3 and 1.5 nm GaN quantum wells are clad by 6nm of AlN on top of a thick AlN buffer grown on sapphire. All samples consisted of 20 quantum wells. The observed peak energy of the emission spectrum is in excellent agreement with a model that includes the strong confinement present in these structures and the existence of the large built-in piezoelectric field and spontaneous polarization present inside the wells. Furthermore, consistent with screening of the in-well field as carriers are injected in the well, a clear blue shift of the emission is observed at short times after carrier injection. Subsequently, as the carriers recombine, the peak emission red-shifts and the screening of the field is reduced. Moreover, the observed lifetimes were energy dependent as should be expected from field dependent elongation of lifetimes due to spatial separation of the injected carriers. Specifically, the decay time at high energies can be fitted by a stretched exponential with a beta value of 0.8 which is consistent with carrier spatial separation. The lifetimes obtained from the fitting are of the order of 1ns, longer than the reported recombination lifetimes in similar GaN/AlGaN MQW's. On the low energy side of the PL feature the intensity time decay becomes exponential with lifetimes ranging from 3 to 10ns. The strong UV emission at room temperature makes these structures promising for UV emitters.

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