Near Gap Photoluminescence of GaAs Grown Directly on InP

1989 ◽  
Vol 145 ◽  
Author(s):  
M. Lamont Schnoes ◽  
T.D. Harris ◽  
W.S. Hobson ◽  
R. M. Lum ◽  
J. K. Klingert
Keyword(s):  
Thermal Expansion ◽  
Valence Band ◽  
Spectral Features ◽  
Thermal Expansion Mismatch ◽  
Photoluminescence Excitation ◽  
Carbon Impurity ◽  
The Third ◽  
Inp Substrates ◽  
Split Valence ◽  
Good Agreement

AbstractWe present a detailed photoluminescence and photoluminescence excitation study of GaAs grown directly on InP substrates by MOCVD. Reliable peak assignments are determined. With these peak assignments, we measure strain and strain uniformity, identify impurities, and assess material quality. Most samples exhibit three distinct spectral features. The two highest energy features are the strain split valence band, the third feature is a carbon impurity. The observed splitting is in good agreement with the value predicted from the thermal expansion mismatch.

Band-Edge Luminescence of MOCVD GaAs Grown Directly on Silicon

1987 ◽  
Vol 102 ◽  
Author(s):  
M. G. Lamont ◽  
T. D. Harris ◽  
R. Sauer ◽  
R. M. Lum ◽  
J. K. Klingert
Keyword(s):  
Temperature Variation ◽  
Valence Band ◽  
Selective Excitation ◽  
Substrate Thickness ◽  
Spectral Features ◽  
Photoluminescence Excitation ◽  
Si Substrates ◽  
Band Edge Luminescence ◽  
Split Valence ◽  
Thick Layers

ABSTRACTWe report a detailed study using photoluminescence and photoluminescence excitation of MOCVD GaAs grown directly on Si substrates. Temperature variation and selective excitation allow reliable assignment of spectral features. This assignment permits measurements of strain and strain uniformity, identification of impurities, and assessment of general materials quality. In 2–5μm thick layers similar spectra are observed with little variation from substrate character. Most samples show one of the two split valence band features plus defect recombination, always including carbon. Strain uniformity varies widely and correlates with substrate thickness. The range of spectra observed from a variety of samples, and guidelines for interpretation of nonresonantly excited spectra will be discussed.

Microstructural and Microchemical Characterization of Nickel Sulfide Inclusions in Plate Glass

1991 ◽  
Vol 49 ◽  
pp. 962-963
Author(s):  
J. Cooper ◽  
O. Popoola ◽  
W. M. Kriven
Keyword(s):  
Thermal Expansion ◽  
Phase Transformation ◽  
Glass Matrix ◽  
Nickel Sulfide ◽  
Plate Glass ◽  
Thermal Expansion Mismatch ◽  
Volume Increase ◽  
Β Phase ◽  
Microchemical Characterization

Nickel sulfide inclusions have been implicated in the spontaneous fracture of large windows of tempered plate glass. Two alternative explanations for the fracture-initiating behaviour of these inclusions have been proposed: (1) the volume increase which accompanies the α to β phase transformation in stoichiometric NiS, and (2) the thermal expansion mismatch between the nickel sulfide phases and the glass matrix. The microstructure and microchemistry of the small inclusions (80 to 250 μm spheres), needed to determine the cause of fracture, have not been well characterized hitherto. The aim of this communication is to report a detailed TEM and EDS study of the inclusions.

scholarly journals Unravelling thermal stress due to thermal expansion mismatch in metal–organic frameworks for methane storage

2021 ◽  
Author(s):  
Jelle Wieme ◽  
Veronique Van Speybroeck
Keyword(s):  
Thermal Expansion ◽  
Thermal Stress ◽  
Pressure Coefficient ◽  
Metal Organic Frameworks ◽  
Methane Storage ◽  
Thermal Expansion Mismatch ◽  
Thermal Pressure ◽  
Temperature Changes ◽  
Metal Organic ◽  
The Impact

Thermal stress is present in metal–organic frameworks undergoing temperature changes during adsorption and desorption. We computed the thermal pressure coefficient as a proxy for this phenomenon and discuss the impact of thermal expansion mismatch.

scholarly journals Valence Band Mixing in GaAs/AlGaAs Quantum Wells Adjacent to Self-Assembled InAlAs Antidots

2019 ◽  
Vol 2019 ◽  
pp. 1-7
Author(s):  
Takuya Kawazu
Keyword(s):  
Optical Properties ◽  
Quantum Wells ◽  
Valence Band ◽  
Energy Barrier ◽  
Heavy Hole ◽  
Electronic States ◽  
Light Hole ◽  
Photoluminescence Excitation ◽  
Band Mixing ◽  
Valence Band Mixing

Optical properties of GaAs/AlGaAs quantum wells (QWs) in the vicinity of InAlAs quantum dots (QDs) were studied and compared with a theoretical model to clarify how the QD strain affects the electronic states in the nearby QW. In0.4Al0.6As QDs are embedded at the top of the QWs; the QD layer acts as a source of strain as well as an energy barrier. Photoluminescence excitation (PLE) measurements showed that the QD formation leads to the increase in the ratio Ie-lh/Ie-hh of the PLE intensities for the light hole (lh) and the heavy hole (hh), indicating the presence of the valence band mixing. We also theoretically calculated the hh-lh mixing in the QW due to the nearby QD strain and evaluated the PLE ratio Ie-lh/Ie-hh.

Alucone Interlayers to Minimize Stress Caused by Thermal Expansion Mismatch between Al2O3 Films and Teflon Substrates

2013 ◽  
Vol 5 (3) ◽  
pp. 1165-1173 ◽  
Author(s):  
Shih-Hui Jen ◽  
Steven M. George ◽  
Robert S. McLean ◽  
Peter F. Carcia
Keyword(s):  
Thermal Expansion ◽  
Thermal Expansion Mismatch ◽  
Al2o3 Films

Reaktionskinetik des Energietransportes zwischen Rekombinationszentren von Elektroluminophoren

1965 ◽  
Vol 20 (12) ◽  
pp. 1648-1654 ◽  
Author(s):  
I. Broser ◽  
H.-E. Gumlich ◽  
R. Moser
Keyword(s):  
Valence Band ◽  
Luminescence Quenching ◽  
Iron Group ◽  
Field Frequency ◽  
Kinetics Of ◽  
Good Agreement

The kinetics of holes in electroluminescence has been calculated by means of simple two- and three-level-models. As a result an equation is given which describes the ratio of intensity of different emission bands and the degree of luminescence quenching by iron group elements as a function of field frequency and temperature. The calculated curves are in good agreement with the values observed in ZnS containing Cu, Mn, Fe, Co, Ni respectively. The kinetics has been used to calculate the energetic separation of acceptor levels from the valence band and other constants.

New Developments for the Description of Oil Leakages by Advective Migration From Submarine Pipelines

2009 ◽  
Vol 131 (3) ◽  
Author(s):  
Renan Martins Baptista ◽  
Ricardo Antonio Francisco Machado ◽  
Marintho Bastos Quadri ◽  
Ariovaldo Bolzan ◽  
André Lourenço Nogueira ◽  
...  
Keyword(s):  
Horizontal Plane ◽  
Immiscible Displacement ◽  
Preliminary Evaluation ◽  
Leakage Detection ◽  
New Developments ◽  
Gravitational Flow ◽  
The Third ◽  
Alternative Approach ◽  
High Standards ◽  
Good Agreement

The significant growth in offshore operations increases the risk of a pipeline rupture, even considering the high standards of safety involved. Throughout a submarine leakage, four different amounts of oil may be accounted. The first one is the oil volume released until the leakage detection. The second one is the volume leaked throughout mitigation initiatives (e.g., pump shutdown and valve closure). The third parcel is the amount released by gravitational flow. Finally, the fourth and last amount of oil is released due to the water-oil entrainment, generally known as advective migration. Normally, a considerable amount of oil is released in this step. It begins just after the internal pipeline pressure becomes equal to the external one. The present work continues to introduce a mathematical alternative approach, based on the theories of perturbation and unstable immiscible displacement, to accurately estimate the leakage kinetics and the amount of oil released by the advective migration phenomenon. Situations considering different hole sizes and thicknesses were tested experimentally and through simulations. Additional experiments were accomplished using smooth and rough edge surfaces, besides different slopes (using the horizontal plane as reference). Those experiments permitted a preliminary evaluation of the importance of these factors. The results obtained with the model showed good agreement with the experimental data in many situations considered.

Shape forming by thermal expansion mismatch and shape memory locking in polymer/elastomer laminates

2017 ◽  
Vol 26 (10) ◽  
pp. 105027 ◽  
Author(s):  
Chao Yuan ◽  
Zhen Ding ◽  
T J Wang ◽  
Martin L Dunn ◽  
H Jerry Qi
Keyword(s):  
Thermal Expansion ◽  
Shape Memory ◽  
Thermal Expansion Mismatch

Rapid shear alignment of sub-10 nm cylinder-forming block copolymer films based on thermal expansion mismatch

Nano Futures ◽  
2018 ◽  
Vol 1 (3) ◽  
pp. 035006
Author(s):  
Samuel M Nicaise ◽  
Karim R Gadelrab ◽  
Amir Tavakkoli K G ◽  
Caroline A Ross ◽  
Alfredo Alexander-Katz ◽  
...  
Keyword(s):  
Thermal Expansion ◽  
Block Copolymer ◽  
Thermal Expansion Mismatch ◽  
Shear Alignment ◽  
Copolymer Films
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