scholarly journals Space‐ and time‐resolved photoluminescence of In‐alloyed GaAs using photoluminescence excitation correlation spectroscopy

1989 ◽  
Vol 66 (2) ◽  
pp. 838-844 ◽  
Author(s):  
M. B. Johnson ◽  
T. C. McGill ◽  
A. T. Hunter
Keyword(s):  
Correlation Spectroscopy ◽  
Photoluminescence Excitation ◽  
Time Resolved ◽  
Space And Time ◽  
Time Resolved Photoluminescence

Space and Time Resolved Photoluminescence of Defects at Dislocations in In-Alloyed GaAs Substrate Material

1987 ◽  
Vol 104 ◽  
Author(s):  
Matthew B. Johnson ◽  
A. T. Hunter ◽  
T. C. McGill
Keyword(s):  
Gaas Substrate ◽  
Surface Recombination ◽  
Substrate Material ◽  
Outer Radius ◽  
Time Resolved ◽  
Space And Time ◽  
Dislocation Cluster ◽  
Pl Intensity ◽  
Time Resolved Photoluminescence ◽  
Intensity Contrast

ABSTRACTWe report a study of dislocations in In-alloyed GaAs substrate material using space and time resolved photoluminescence (PL). PL intensity maps show that an isolated dislocation cluster is in the center of a dark region with a 50μm radius surrounded by a bright region with an outer radius of 150μm. Lifetime measurements were made in the bright and dark regions. Values as long as 3.5 ns and as short as 250 psec were observed in adjacent bright and dark regions. These measurements indicate that the PL intensity contrast is explained by lifetime variations in these features. This supports the view that the dislocation cluster acts as a source and sink for defects which govern the lifetime in the surrounding material. Temperature dependence of the lifetime indicates two different defects may be involved. Both of these produce deep levels, neither one of which is EL2. A surface passivation technique is used to show that surface recombination is not important to the PL intensity contrast.

Pressure Dependence of a Deep Excitonic Level in Silicon

1989 ◽  
Vol 163 ◽  
Author(s):  
G.A. Northrop ◽  
D.J. Wolford
Keyword(s):  
Hydrostatic Pressure ◽  
Pressure Dependence ◽  
Luminescence Intensity ◽  
Deep Level ◽  
Optically Active ◽  
Photoluminescence Excitation ◽  
Time Resolved ◽  
Time Resolved Photoluminescence ◽  
Effect Of Hydrostatic Pressure ◽  
High Hydrostatic Pressures

AbstractCertain optically active defects in silicon provide a unique opportunity to observe, in detail, the effect of hydrostatic pressure on a deep level. We present a photoluminescence (5 – 100K) study of one such defect, the I, radiation-damage center, under high hydrostatic pressures (1–50 kbar). While the energy variation of this level indicates the expected mutli-band nature typical of a deep level, a severe and continuous reduction in the observed luminescence intensity was also observed. Temperature dependence, time resolved photoluminescence, and photoluminescence excitation spectroscopy are employed to attempt to discern the mechanism involved.

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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