Interface Recombination in III/V Heterostructures Investigated Through the Power Dependence of Excitonic Photoluminescence

1991 ◽  
Vol 240 ◽  
Author(s):  
M. MüLlenborn ◽  
N. M. Haegel
Keyword(s):  
Charge Carrier ◽  
Lattice Mismatch ◽  
Gaas Layer ◽  
Generation Process ◽  
Carrier Distribution ◽  
Interface Recombination ◽  
Charge Carrier Diffusion ◽  
Photon Recycling ◽  
Excitonic Luminescence

ABSTRACTPhotoluminescence spectra of AlGaAs/GaAs heterostructures with layer thicknesses in the micrometer range show excitonic recombination peaks from the AlGaAs as well as the GaAs layer. Luminescence in the buried GaAs layer may be produced by charge carrier diffusion across the interface and/or photon recycling. We have monitored the luminescence intensity from both layers as a function of laser power in order to determine the dominant generation process in the GaAs layer. The ambi polar diffusion equation has been solved to derive the charge carrier distribution. Based on these data the relative intensities of the AlGaAs and the GaAs excitonic luminescence can be used to obtain information about the interface recombination in a nondestructive way. This characterization method has been applied to investigate the quality of GaAsP/GaAs interfaces as a function of increasing lattice mismatch and dislocation density.

Anisotropic Charge Carrier Diffusion Correlated to Ferroelastic Twin Domains in MAPbI3 Perovskite

2019 ◽  
Author(s):  
Ilka M. Hermes ◽  
Andreas Best ◽  
Julian Mars ◽  
Sarah M. Vorpahl ◽  
Markus Mezger ◽  
...  
Keyword(s):  
Charge Carrier ◽  
Carrier Diffusion ◽  
Charge Carrier Diffusion

scholarly journals Extracting in Situ Charge Carrier Diffusion Parameters in Perovskite Solar Cells with Light Modulated Techniques

2021 ◽  
pp. 2248-2255
Author(s):  
Agustín Bou ◽  
Haralds A̅boliņš ◽  
Arjun Ashoka ◽  
Héctor Cruanyes ◽  
Antonio Guerrero ◽  
...  
Keyword(s):  
Solar Cells ◽  
Charge Carrier ◽  
Perovskite Solar Cells ◽  
Carrier Diffusion ◽  
Diffusion Parameters ◽  
Charge Carrier Diffusion

A Tem study of GaN Grown by ELO on (0001) 6H-SiC

1999 ◽  
Vol 595 ◽  
Author(s):  
P. Ruterana ◽  
B. Beaumont ◽  
P. Gibart ◽  
Y. Melnik
Keyword(s):  
Basal Plane ◽  
Lattice Mismatch ◽  
Early Stage ◽  
Vapour Phase ◽  
Epitaxial Layers ◽  
Prismatic Plane ◽  
Vapour Phase Epitaxy ◽  
Hexagonal Shape ◽  
To Come

AbstractThe misfit between GaN and 6H-SiC is 3.5% instead of 16% with sapphire, the epitaxial layers have similar densities of defects on both substrates. Moreover, the lattice mismatch between AlN and 6H-SiC is only 1%. Therefore, epitaxial layer overgrowth (ELO) of GaN on AlN/6H-SiC could be a route to further improve the quality of epitaxial layers. AlN has been grown by Halide Vapour Phase Epitaxy (HVPE) on (0001) 6H-SiC, thereafter a dielectric SiO2 mask was deposited and circular openings were made by standard photolithography and reactive ion etching. We have examined GaN layers at an early stage of coalescence in order to identify which dislocations bend and try to understand why. The analysed islands have always the same hexagonal shape, limited by {0110} facets. The a type dislocations are found to fold many times from basal to the prismatic plane, whereas when a+c dislocations bend to the basal plane, they were not seen to come back to a prismatic one.

INFLUENCE OF THE LATTICE MISMATCH ON THE PHOTOLUMINESCENCE BAND-TAIL PARAMETER IN InGaAsP/InP HETEROSTRUCTURES

2001 ◽  
Vol 15 (17n19) ◽  
pp. 708-711
Author(s):  
A. IRIBARREN
Keyword(s):  
Linear Dependence ◽  
Lattice Mismatch ◽  
Semiconductor Heterostructures ◽  
Full Width ◽  
Half Maximum ◽  
Photoluminescence Spectra ◽  
Band Tail ◽  
Photoluminescence Band ◽  
Grown Layer

The compositional inhomogeneities in semiconductor heterostructures leads to diminishing the quality of the grown layer which reflects in the shape of the rocking curves, where the full width at half maximum (FWHM) of the peaks is larger. Consequently, the quality of the layers characterized by an increase of the disorder also reflects in the band-tail parameter ( E 0) of the photoluminescence spectra. A linear dependence of the FWHM with the lattice mismatch (Δa) was found. The dependence of E 0 as a function of FWHM are presented. It was found that E 0 keep constant up to Δ a / a ≅ 0.15% and FWHM ≅ 50" from where it begins to increase.

scholarly journals A Probabilistic Approach to Error Detection&Correction for Tree-Mapping Grammars

2018 ◽  
Vol 111 (1) ◽  
pp. 97-112
Author(s):  
Tim vor der Brück
Keyword(s):  
Error Detection ◽  
Basic Assumption ◽  
Probabilistic Approach ◽  
Large Set ◽  
Generation Process ◽  
Input Structure ◽  
Error Detection And Correction ◽  
Complete Failure ◽  
Automatic Error

Abstract Rule-based natural language generation denotes the process of converting a semantic input structure into a surface representation by means of a grammar. In the following, we assume that this grammar is handcrafted and not automatically created for instance by a deep neural network. Such a grammar might comprise of a large set of rules. A single error in these rules can already have a large impact on the quality of the generated sentences, potentially causing even a complete failure of the entire generation process. Searching for errors in these rules can be quite tedious and time-consuming due to potentially complex and recursive dependencies. This work proposes a statistical approach to recognizing errors and providing suggestions for correcting certain kinds of errors by cross-checking the grammar with the semantic input structure. The basic assumption is the correctness of the latter, which is usually a valid hypothesis due to the fact that these input structures are often automatically created. Our evaluation reveals that in many cases an automatic error detection and correction is indeed possible.

scholarly journals Influence of Low Temperature-Grown GaAs on Lateral Thermal Oxidation of Al0.98Ga0.02As

2000 ◽  
Vol 623 ◽  
Author(s):  
J. C. Ferrer ◽  
Z. Liliental-Weber ◽  
H. Reese ◽  
Y.J. Chiu ◽  
E. Hu
Keyword(s):  
Low Temperature ◽  
Thermal Oxidation ◽  
Oxidation Process ◽  
Gaas Layer ◽  
Transmission Electron ◽  
Low Temperature Gaas ◽  
Reference Samples ◽  
Thermal Oxidation Process ◽  
Low Temperature Grown Gaas

AbstractThe lateral thermal oxidation process of Al0.98Ga0.02As layers has been studied by transmission electron microscopy. Growing a low-temperature GaAs layer below the Al0.98Ga0.02As has been shown to result in better quality of the oxide/GaAs interfaces compared to reference samples. While the later have As precipitation above and below the oxide layer and roughness and voids at the oxide/GaAs interface, the structures with low-temperature have less As precipitation and develop interfaces without voids. These results are explained in terms of the diffusion of the As toward the low temperature layer. The effect of the addition of a Si02 cap layer is also discussed.

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