Study of delocalized and localized states in ZnSeO layers with photoluminescence, micro-photoluminescence, and time-resolved photoluminescence

2019 ◽  
Vol 125 (20) ◽  
pp. 205702 ◽  
Author(s):  
M. Wełna ◽  
M. Baranowski ◽  
R. Kudrawiec
Keyword(s):  
Localized States ◽  
Time Resolved ◽  
Time Resolved Photoluminescence

scholarly journals Regions of Different Confinement in Low-Dimensional AlyInxGa1−x−yN Quantum Structures

2007 ◽  
Vol 2007 ◽  
pp. 1-6 ◽  
Author(s):  
A. Gröning ◽  
V. Pérez-Solórzano ◽  
M. Jetter ◽  
H. Schweizer
Keyword(s):  
Growth Parameters ◽  
Growth Conditions ◽  
Localized States ◽  
Time Resolved ◽  
Organic Vapor ◽  
Growth Interruption ◽  
Metal Organic ◽  
Low Dimensional ◽  
Time Resolved Photoluminescence ◽  
State Filling

The optical properties of metal-organic vapor phase epitaxy grown AlyInxGa1−x−yN quantum dot structures have been studied by time-resolved photoluminescence experiments. We investigated the recombination dynamics of the photo-exited carriers in dependence of the growth parameters such as aluminium flow and the duration of the growth interruption after the dot deposition. Our results confirm the presence of localized states, where the degree of localization is strongly dependent on the growth conditions. To describe this behavior, we propose a band structure with coupled potentials for these nanostructures. Finally, we demonstrate state filling to prove the zero-dimensional character of the strongly localized states in our quaternary quantum dots.

Temperature and Time-Resolved Dependence of Photoluminescence in InGaN Quantum Dots

2013 ◽  
Vol 750-752 ◽  
pp. 927-930
Author(s):  
Cheng Chen ◽  
Zhi Ren Qiu ◽  
Xiang Ping Shu ◽  
Zeng Cheng Li ◽  
Jian Ping Liu ◽  
...  
Keyword(s):  
Decay Time ◽  
Peak Position ◽  
Localized States ◽  
Fast Decay ◽  
Time Resolved ◽  
Experimental Systems ◽  
Slow Decay ◽  
Double Exponential ◽  
Increasing Temperature ◽  
Time Resolved Photoluminescence

Temperature dependence of photoluminescence (PL) and time resolved photoluminescence (TRPL) were obtained by two experimental systems. The relative intensity and peak position of PL show S-shift variation with increasing temperature, which may result from temperature induce carriers redistribution. Fast decay time and slow decay time were fitted by double exponential function from decay curves of TRPL at different emission energy, and the decreasing trend of both fast decay and slow decay time with increasing photon energy is attributed to various channels of recombination in shallow and deep localized states.

Time-Resolved Photoluminescence Studies of InxGa1−xAs1−yNy

1999 ◽  
Vol 607 ◽  
Author(s):  
M. Smith ◽  
R. A. Mair ◽  
J.Y. Lin ◽  
H. X. Jiang ◽  
E. D. Jones ◽  
...  
Keyword(s):  
Metalorganic Chemical Vapor Deposition ◽  
Deposition Time ◽  
Chemical Vapor ◽  
Localized States ◽  
Time Resolved ◽  
Emission Energy ◽  
Annealing Conditions ◽  
Photoluminescence Studies ◽  
Recombination Lifetimes ◽  
Time Resolved Photoluminescence

AbstractTime-resolved photoluminescence spectroscopy has been used to investigate carrier decay dynamics in InxGa1−xAs1−yNy (x ∼ 0.03, y ∼ 0.01) epilayers grown on GaAs by metalorganic chemical vapor deposition. Time-resolved PL measurements, performed for various excitation intensities and sample temperatures, indicate that the broad PL emission at low temperature is dominated by localized exciton recombination. Lifetimes in the range of 0.07–0.34 ns are measured; these photoluminescence lifetimes are significantly shorter than corresponding values obtained for GaAs. In particular, we observe an emission energy dependence of the decay lifetime at 10 K, whereby the lifetime decreases with increasing emission energy across the PL spectrum. This behavior is characteristic of a distribution of localized states, which arises from alloy fluctuations. We have also studied the effects of post-growth rapid thermal annealing (RTA) on the integrated photoluminescence emission intensity, which indicate that the optimal annealing conditions is 690 °C when annealed for 120 seconds in a nitrogen ambient.

scholarly journals Time Resolved Photoluminescence of Si-doped High Al Mole Fraction AlGaN Epilayers Grown by Plasma-Enhanced Molecular Beam Epitaxy

2003 ◽  
Vol 798 ◽  
Author(s):  
Madalina Furis ◽  
Alexander N. Cartwright ◽  
Jeonghyun Hwang ◽  
William J. Schaff
Keyword(s):  
Mole Fraction ◽  
Slow Component ◽  
Localized States ◽  
Yellow Emission ◽  
Alloy Formation ◽  
Temperature Dependent ◽  
Time Resolved ◽  
Si Doped ◽  
Pl Spectrum ◽  
Time Resolved Photoluminescence

ABSTRACTWe report on detailed temperature dependent, time-resolved photoluminescence (TRPL) studies of Si-doped AlGaN epilayers. In these samples, the Al concentration varies from 25% to 66%. The samples were found to exhibit metallic-like temperature-independent conductivity. The deep level “yellow” emission, whose presence would indicate the existence of a large number of defects associated with growth, Si incorporation, and/or alloy formation, is absent. In addition to emission corresponding to the donor-bound exciton, the PL spectrum exhibits features associated with transitions involving localized carriers. This assignment of the emission mechanisms is based on the activation energies extracted from the temperature dependent photoluminescence (PL) quenching. Specifically, at room temperature the PL spectrum is dominated by transitions involving localized states. The localization energy varied from sample to sample and was observed to be between 115 meV to 200 meV. The PL intensity decay in the lower Al mole fraction epilayers exhibits a slow component associated with the presence of donor-bound excitons.

Exciton dynamics in thick GaN MOVPE epilayers deposited on sapphire.

1997 ◽  
Vol 2 ◽  
Author(s):  
J. Allègre ◽  
P. Lefebvre ◽  
J. Camassel ◽  
B. Beaumont ◽  
Pierre Gibart
Keyword(s):  
Layer Thickness ◽  
Buffer Layers ◽  
Rate Equations ◽  
Time Resolved ◽  
Versus Layer ◽  
Level Model ◽  
Shallow Impurities ◽  
Aln Buffer ◽  
Time Resolved Photoluminescence

Time-resolved photoluminescence spectra have been recorded on three GaN epitaxial layers of thickness 2.5 μm, 7 μm and 16 μm, at various temperatures ranging from 8K to 300K. The layers were deposited by MOVPE on (0001) sapphire substrates with standard AlN buffer layers. To achieve good homogeneities, the growth was in-situ monitored by laser reflectometry. All GaN layers showed sharp excitonic peaks in cw PL and three excitonic contributions were seen by reflectivity. The recombination dynamics of excitons depends strongly upon the layer thickness. For the thinnest layer, exponential decays with τ ~ 35 ps have been measured for both XA and XB free excitons. For the thickest layer, the decay becomes biexponential with τ1 ~ 80 ps and τ2 ~ 250 ps. These values are preserved up to room temperature. By solving coupled rate equations in a four-level model, this evolution is interpreted in terms of the reduction of density of both shallow impurities and deep traps, versus layer thickness, roughly following a L−1 law.

ZnCdO/ZnMgO and ZnO/AlGaN Heterostructures for UV and Visible Light Emitters

2005 ◽  
Vol 892 ◽  
Author(s):  
Andrei Osinsky ◽  
Jianwei Dong ◽  
J. Q. Xie ◽  
B. Hertog ◽  
A. M. Dabiran ◽  
...  
Keyword(s):  
Molecular Beam ◽  
Compositional Analysis ◽  
Optical Emission ◽  
Rf Plasma ◽  
Light Emitters ◽  
Time Resolved ◽  
Light Emitting ◽  
Spatially Resolved ◽  
Time Resolved Photoluminescence ◽  
Made In

AbstractThis paper reviews of some of the progress made in the development of ZnO-based light emitting diodes (LEDs). n-ZnO/p-AlGaN-based heterostructures have been successfully for the fabrication of UV emitting LEDs that have operated at temperatures up to 650K, suggesting an excitonic origin for the optical transitions. RF-plasma-assisted molecular beam epitaxy has been used to grow epitaxial CdxZn1-xO films on GaN/sapphire structure. These films have a single-crystal wurtzite structure as demonstrated by structural and compositional analysis. High quality CdxZn1-xO films were grown with up to x=0.78 mole fraction as determined by RBS and SIMS techniques. Optical emission ranging from purple (Cd0.05Zn0.95O) to yellow (Cd0.29Zn0.71O) was observed. Compositional fluctuations in a Cd0.16Zn0.84O films were not detected by spatially resolved CL measurements, although intensity fluctuation with features of ∼0.5 μm diameter were seen on the intensity maps. Time resolved photoluminescence shows multi-exponential decay with 21 psec. and 49±3 psec. lifetimes, suggesting that composition micro-fluctuations may be present in Cd0.16Zn0.84O film.

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