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 Electric Field Distribution in strained p-i-n GaN/InGaN multiple quantum well structures.

1999 ◽  
Vol 4 (1) ◽  
Author(s):  
A.N. Cartwright ◽  
Paul M. Sweeney ◽  
Thomas Prunty ◽  
David P. Bour ◽  
Michael Kneissl
Keyword(s):  
Quantum Well ◽  
Electric Field Distribution ◽  
Theoretical Calculations ◽  
Multiple Quantum Well ◽  
Multiple Quantum ◽  
Time Resolved ◽  
Quantum Well Structures ◽  
Piezoelectric Field ◽  
Piezoelectric Fields ◽  
Time Resolved Photoluminescence

The presence of piezoelectric fields within p-i-n GaN/InGaN multiple quantum well structures is discussed. Time integrated and time-resolved photoluminescence measurements and theoretical calculations of the effect of these fields is presented. Furthermore, a description of how these fields influence the carrier dynamics and a discussion of how the piezoelectric field effects the design of GaN/InGaN devices is presented.

EXCITONIC SIDE BANDS OF INNER-SHELL EXCITATIONS IN RARE GAS SOLIDS

2002 ◽  
Vol 09 (02) ◽  
pp. 1333-1338 ◽  
Author(s):  
S. VIELHAUER ◽  
M. KIRM ◽  
V. KISAND ◽  
E. NEGODIN ◽  
E. SOMBROWSKI ◽  
...  
Keyword(s):  
Free Exciton ◽  
Rare Gas ◽  
Excitation Threshold ◽  
Energy Position ◽  
Excitation Spectra ◽  
Electron Hole ◽  
Time Resolved ◽  
Ionization Limit ◽  
Time Resolved Photoluminescence ◽  
Hole Recombination

Valence-exciton luminescence under inner-shell excitation of the rare gas solids Xe, Kr, and Ar has been measured using time-resolved photoluminescence. Two different processes for exciton creation can be distinguished: creation of "prompt" excitons immediately after excitation (within the experimental time resolution), and creation of "delayed" excitons through electron–hole recombination. The decay structure of the exciton emission in the range of inner-shell excitation is characterized by the coexistence of the two processes. Time-resolved excitation spectra near the 2p edge in Ar, the 3d edge in Kr, and the 4d edge in Xe are discussed. The process of prompt exciton creation is strongly enhanced above an excitation threshold at the energy position of the ionization limit of the core state plus the energy of the valence free exciton.

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.

Time Resolved Photoluminescence from Patterned GaAs/AlGaAs Multiple Quantum Well Structures

1993 ◽  
Vol 326 ◽  
Author(s):  
Xuelong Cao ◽  
Ahn Goo Choo ◽  
L. M. Smith ◽  
Howard E. Jackson ◽  
P. Chen ◽  
...  
Keyword(s):  
Quantum Well ◽  
Multiple Quantum Well ◽  
Multiple Quantum ◽  
Time Resolved ◽  
Quantum Well Structures ◽  
Time Resolved Photoluminescence

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.

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