Structural Properties of (GaIn)(AsN)/GaAs MQW Structures Grown by MOVPE

1999 ◽  
Vol 595 ◽  
Author(s):  
C. Giannini ◽  
E. Carlino ◽  
L. Tapfer ◽  
F. Höhnsdorf ◽  
J. Koch ◽  
...  
Keyword(s):  
High Resolution ◽  
Structural Properties ◽  
Secondary Ion Mass Spectrometry ◽  
Defect Density ◽  
Vapour Phase ◽  
Structural Quality ◽  
Material System ◽  
Vapour Phase Epitaxy ◽  
High Resolution Tem ◽  
Strain Modulation

AbstractIn this work, we investigate the structural properties of (GaIn)(AsN)/GaAs multiplequantum wells (MQW) grown at low temperature by metalorganic vapour phase epitaxy. The structural properties, in particular the In- and N-incorporation, the lattice strain (strain modulation), the structural perfection of the metastable (GaIn)(AsN) material system and the structural quality of the (GaIn)(AsN)/GaAs interfaces are investigated by means of high-resolution x-ray diffraction, transmission electron microscopy (TEM), and secondary ion mass spectrometry. We demonstrate that (GaIn)(AsN) layers of high structural quality can be fabricated up to lattice mismatches of 4%. Our experiments reveal that N and In atoms are localized in the quaternary material and no evidences of In-segregation or N-interdiffusion could be found. TEM analyses reveal a low defect density in the highly strained layers, but no clustering or interface undulation could be detected. High-resolution TEM images show that (GaIn)(AsN)/GaAs interfaces are slightly rougher than GaAs/(GaIn)(AsN) ones.

scholarly journals Structural Properties of (GaIn)(AsN)/GaAs MQW Structures Grown by MOVPE

2000 ◽  
Vol 5 (S1) ◽  
pp. 259-265 ◽  
Author(s):  
C. Giannini ◽  
E. Carlino ◽  
L. Tapfer ◽  
F. Höhnsdorf ◽  
J. Koch ◽  
...  
Keyword(s):  
High Resolution ◽  
Quantum Wells ◽  
Structural Properties ◽  
Secondary Ion Mass Spectrometry ◽  
Defect Density ◽  
Vapour Phase ◽  
Structural Quality ◽  
Multiple Quantum ◽  
Material System ◽  
Vapour Phase Epitaxy

In this work, we investigate the structural properties of (GaIn)(AsN)/GaAs multiple quantum wells (MQW) grown at low temperature by metalorganic vapour phase epitaxy. The structural properties, in particular the In- and N-incorporation, the lattice strain (strain modulation), the structural perfection of the metastable (GaIn)(AsN) material system and the structural quality of the (GaIn)(AsN)/GaAs interfaces are investigated by means of high-resolution x-ray diffraction, transmission electron microscopy (TEM), and secondary ion mass spectrometry. We demonstrate that (GaIn)(AsN) layers of high structural quality can be fabricated up to lattice mismatches of 4%. Our experiments reveal that N and In atoms are localized in the quaternary material and no evidences of In-segregation or N-interdiffusion could be found. TEM analyses reveal a low defect density in the highly strained layers, but no clustering or interface undulation could be detected. High-resolution TEM images show that (GaIn)(AsN)/GaAs interfaces are slightly rougher than GaAs/(GaIn)(AsN) ones.

scholarly journals Role of dislocations in nitride laser diodes with different indium content

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Agata Bojarska-Cieślińska ◽  
Łucja Marona ◽  
Julita Smalc-Koziorowska ◽  
Szymon Grzanka ◽  
Jan Weyher ◽  
...  
Keyword(s):  
Quantum Wells ◽  
Defect Density ◽  
Laser Diodes ◽  
Diffusion Path ◽  
Vapour Phase ◽  
Indium Content ◽  
Nonradiative Recombination ◽  
Light Emitters ◽  
Vapour Phase Epitaxy

AbstractIn this work we investigate the role of threading dislocations in nitride light emitters with different indium composition. We compare the properties of laser diodes grown on the low defect density GaN substrate with their counterparts grown on sapphire substrate in the same epitaxial process. All structures were produced by metalorganic vapour phase epitaxy and emit light in the range 383–477 nm. We observe that intensity of electroluminescence is strong in the whole spectral region for devices grown on GaN, but decreases rapidly for the devices on sapphire and emitting at wavelength shorter than 420 nm. We interpret this behaviour in terms of increasing importance of dislocation related nonradiative recombination for low indium content structures. Our studies show that edge dislocations are the main source of nonradiative recombination. We observe that long wavelength emitting structures are characterized by higher average light intensity in cathodoluminescence and better thermal stability. These findings indicate that diffusion path of carriers in these samples is shorter, limiting the amount of carriers reaching nonradiative recombination centers. According to TEM images only mixed dislocations open into the V-pits, usually above the multi quantum wells thus not influencing directly the emission.

Studies of Critical Current Density Enhancement in (Cax Y1−x)Ba2Cu4O8 (1:2:4)

1991 ◽  
Vol 235 ◽  
Author(s):  
P. K. Narwankar ◽  
M. R. Chandrachood ◽  
M. Fendorf ◽  
D. E. Morris ◽  
A. P. B. Sinha ◽  
...  
Keyword(s):  
High Resolution ◽  
Critical Current Density ◽  
Critical Current ◽  
Current Density ◽  
Defect Density ◽  
High Density ◽  
Planar Defects ◽  
High Defect Density ◽  
Density Enhancement ◽  
High Resolution Tem

ABSTRACTSamples with the stoichiometry (CaxY1−x)Ba2Cu4O8, x = 0, 0.1 were synthesized at P(O2) = 25 and 200 bar. High Resolution TEM images for the samples synthesized at 25 bar show a high density of planar defects as compared to almost defect free microstructure of Ca0.1Y0.9Ba2Cu4O8 synthesized at 200 bar. The intragrain critical current density of the high defect density samples is however about 100 times lower that that of Ca0.1Y0.9Ba2Cu4O8 synthesized at P(O2) = 200 bar.

scholarly journals Гетероструктуры квантово-каскадных лазеров с неселективным заращиванием методом газофазной эпитаксии

2021 ◽  
Vol 47 (24) ◽  
pp. 46
Author(s):  
А.В. Бабичев ◽  
А.Г. Гладышев ◽  
Д.В. Денисов ◽  
В.В. Дюделев ◽  
Д.А. Михайлов ◽  
...  
Keyword(s):  
Quantum Cascade Laser ◽  
Surface Defects ◽  
Vapour Phase ◽  
Threshold Current ◽  
Threshold Current Density ◽  
Structural Quality ◽  
Vapour Phase Epitaxy ◽  
Quantum Cascade ◽  
Laser Heterostructures ◽  
Cleaved Facets

The possibility of fabrication of 4.6 µm spectral range quantum-cascade laser heterostructures by molecular-beam epitaxy technique with non-selective overgrowth by the metalorganic vapour-phase epitaxy is shown. The active region of the laser was formed on the basis of a heteropair of In0.67Ga0.33As/In0.36Al0.64As solid alloys. The waveguide claddings are formed by indium phosphide. The results of surface defects inspection and X-ray diffraction analysis of quantum-cascade laser heterostructures allow to conclude that the structural quality of the heterostructures is high and the estimated value of the root mean square surface roughness does not exceed 0.7 nm. Lasers with four cleaved facets exhibit lasing at room temperature with a relatively low threshold current density of the order of 1 kA /cm2.

scholarly journals Domain Structure of Thick GaN Layers Grown by Hydride Vapor Phase Epitaxy

1999 ◽  
Vol 4 (S1) ◽  
pp. 197-202
Author(s):  
T. Paskova ◽  
E.B. Svedberg ◽  
L.D. Madsen ◽  
R. Yakimova ◽  
I.G. Ivanov ◽  
...  
Keyword(s):  
Growth Rate ◽  
Growth Rates ◽  
High Growth ◽  
Vapour Phase ◽  
Hydride Vapor Phase Epitaxy ◽  
Spiral Growth ◽  
Structural Quality ◽  
Vapour Phase Epitaxy ◽  
Force Microscopy ◽  
Atomic Force

The crystal structure and surface morphology of hydride vapour phase epitaxy grown thick (12-105 μm) GaN layers have been investigated as a function of growth rate using several structure sensitive techniques like atomic force microscopy (AFM), x-ray diffraction (XRD) in ω-2θ and ω-rocking curve measurements as well as low temperature photoluminescence (PL). PL and XRD measurements reveal rather narrow lines: full width at half maximum (FWHM) values of the strongest donor-bound exciton line are in the range from 6.0 to1.8 meV and ω-2θ FWHM values are between 80 and 23 arcsec indicating good structural quality of the films. The ω-rocking curves show a single peak for the thinnest films with a FWHM of 250 arcsec and multiple peaks with FWHM of about 250-350 arcsec in thicker films indicating the formation of several high-quality domains when increasing either thickness or growth rate. Optical microscopy and AFM images reveal a domain type of morphology and also show an appearance of spiral hillocks in layers grown at growth rates exceeding a critical value. We interpret these results as dominating 2D multilayer growth at low growth rates, and competing 2D multilayer and spiral growth mechanisms at high growth rates.

Improvements in the structural quality of Al0.48In0.52As grown by low pressure metal-organic vapour-phase epitaxy

1988 ◽  
Vol 3 (3) ◽  
pp. 223-226 ◽  
Author(s):  
J I Davies ◽  
P D Hodson ◽  
A C Marshall ◽  
M D Scott ◽  
R J M Griffiths
Keyword(s):  
Low Pressure ◽  
Vapour Phase ◽  
Structural Quality ◽  
Vapour Phase Epitaxy ◽  
Metal Organic ◽  
Organic Vapour

GaN and AlN Layers Grown by Nano Epitaxial Lateral Overgrowth Technique on Porous Substrates

1999 ◽  
Vol 595 ◽  
Author(s):  
M. Mynbaeva ◽  
A. Titkov ◽  
A. Kryzhanovski ◽  
A. Zubrilov ◽  
V. Ratnikov ◽  
...  
Keyword(s):  
Surface Morphology ◽  
Defect Density ◽  
Crack Density ◽  
Vapour Phase ◽  
Epitaxial Lateral Overgrowth ◽  
Vapour Phase Epitaxy ◽  
Nano Scale ◽  
Density Reduction ◽  
Lateral Overgrowth ◽  
Porous Substrates

AbstractDefect density and stress reduction in heteroepitaxial GaN and AlN materials is one of the main issues in group III nitride technology. Recently, significant progress in defect density reduction in GaN layers has been achieved using lateral overgrowth technique. In this paper, we describe a novel technique based on nano-scale epitaxial lateral overgrowth.GaN layers were overgrown by hydride vapour phase epitaxy (HVPE) on porous GaN. Porous GaN was formed by anodization of GaN layers grown previously on SiC ŝubstrates. Pore's size was in nano-scale range.Thickness of overgrown layers ranged from 2 to 120 microns. It was shown that GaN layers overgrown on porous GaN have good surface morphology and high crystalline quality. The surface of overgrown GaN material was uniform and flat without any traces of porous structure. Raman spectroscopy measurements indicated that the stress in the layers grown on porous GaN was reduced down to 0.1 - 0.2 GPa, while the stress in the layers grown directly on 6H-SiC substrates remains at its usual level of about 1.3 GPa.Preliminary experiments were done on HVPE growth of AlN layer on porous substrates. Improvement of surface morphology and crack density reduction has been observed.

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