Photoluminescence of MBE and MOCVD ZnTe Films on GaAs

1987 ◽  
Vol 102 ◽  
Author(s):  
B. A. Wilson ◽  
Carl E. Bonner ◽  
R. D. Feldman ◽  
R. F. Austin ◽  
D. W. Kisker ◽  
...  
Keyword(s):  
Low Temperature ◽  
Growth Temperature ◽  
Growth Conditions ◽  
Growth Chamber ◽  
Mbe Growth ◽  
Pl Spectra ◽  
Gaas Substrates ◽  
Optimal Value ◽  
Stress Levels ◽  
Low Temperature Photoluminescence

ABSTRACTWe present low-temperature photoluminescence (PL) spectra of MBE and MOCVD ZnTe layers deposited on (100) GaAs substrates under different growth conditions. Strong bands associated with Zn vacancies are observed in the MBE materials, while the MOCVD spectra are dominated by sharp impurity-related lines. Stress levels less than 0.1 kbar are determined for both the MBE and MOCVD layers. A study of the effects of the Zn:Te ratio in the MBE growth chamber reveals an optimal value of −2.2 for a growth temperature of 325°C.

Point Defect Changes in CuGaSe2 Induced by Gas Annealing

2003 ◽  
Vol 763 ◽  
Author(s):  
Akimasa Yamada ◽  
Akihiko Nishio ◽  
Paul. Fons ◽  
Hajime Shibata ◽  
Koji Matsubara ◽  
...  
Keyword(s):  
Low Temperature ◽  
Point Defect ◽  
Intrinsic Defect ◽  
Pl Spectra ◽  
Gaas Substrates ◽  
Cap Layer ◽  
Defect Species ◽  
Low Temperature Photoluminescence

AbstractEpitaxial CuGaSe2 films were grown on GaAs substrates under Cu-excess conditions to obtain stoichiometric compositions. The films were annealed in Ar, Sex or O2 ambients with or without a Cu or Cu-Se cap layer with the intention of changing the intrinsic defect concentrations. Samples were evaluated using low-temperature photoluminescence (PL) measurements. Annealing of the samples dramatically changed the PL spectra indicating that not only interdiffusion had occurred, but defect species and populations were changed. Comprehensive consideration of the changes led to the conclusion that the emissions at 1.62 eV, 1.66 eV and in the range from 1.2 to 1.4 eV are related to specific defects of Se vacancies, Cu vacancy-Se vacancy complexes and interstitial Cu, respectively.

Temperature Dependent Quasi-Periodic Facetting of AlAs Grown by MBE on (100) GaAs Substrates

1993 ◽  
Vol 312 ◽  
Author(s):  
Richard Mirin ◽  
Mohan Krishnamurthy ◽  
James Ibbetson ◽  
Arthur Gossard ◽  
John English ◽  
...  
Keyword(s):  
Growth Conditions ◽  
High Energy ◽  
High Energy Electron ◽  
Temperature Dependent ◽  
Cross Sectional ◽  
Mbe Growth ◽  
Atomic Force ◽  
Gaas Substrates ◽  
Transmission Electron ◽  
Facet Formation

AbstractHigh temperature (≥ 650°C) MBE growth of AlAs and AlAs/GaAs superlattices on (100) GaAs is shown to lead to quasi-periodic facetting. We demonstrate that the facetting is only due to the AlAs layers, and growth of GaAs on top of the facets replanarizes the surface. We show that the roughness between the AlAs and GaAs layers increases with increasing number of periods in the superlattice. The roughness increases to form distinct facets, which rapidly grow at the expense of the (100) surface. Within a few periods of the initial facet formation, the (100) surface has disappeared and only the facet planes are visible in cross-sectional transmission electron micrographs. At this point, the reflection high-energy electron diffraction pattern is spotty, and the specular spot is a distinct chevron. We also show that the facetting becomes more pronounced as the substrate temperature is increased from 620°C to 710°C. Atomic force micrographs show that the valleys enclosed by the facets can be several microns long, but they may also be only several nanometers long, depending on the growth conditions.

Study of Diffusion Length and Alloy Segregation in MOCVD AlGaAs

1987 ◽  
Vol 102 ◽  
Author(s):  
J. L. Bradshaw ◽  
W. J. Choyke ◽  
Z. C. Feng ◽  
D. L. Meier ◽  
R. L. Messham
Keyword(s):  
Low Temperature ◽  
Diffusion Length ◽  
Electron Diffusion ◽  
Direct Excitation ◽  
Gaas Substrates ◽  
Electron Diffusion Length ◽  
Alloy Segregation ◽  
Low Temperature Photoluminescence

ABSTRACTVarious thicknesses of AlGaAs are grown on GaAs substrates by MOCVD. Low temperature photoluminescence of the substrate is observed even for layers of AlGaAs 24μm thick. Direct excitation by the 488.0 nm pumping radiation and excitation by reradiation from the AlGaAs are eliminated as causes. From photoluminescence and EBIC studies, evidence is given to show that the substrate luminescence is caused by a much larger than expected electron diffusion length. A small trace of GaAs luminescence may be due to alloy segregation in the AlGaAs films themselves.

Investigation of Roughness at InP/InAs Interfaces

1992 ◽  
Vol 280 ◽  
Author(s):  
M.J.S.P. Brasil ◽  
R. E. Nahory ◽  
M. C. Tamargo ◽  
S. Schwarz
Keyword(s):  
Low Temperature ◽  
Quantum Wells ◽  
Mass Spectroscopy ◽  
Growth Temperature ◽  
Interface Roughness ◽  
Chemical Beam Epitaxy ◽  
Photoluminescence Spectra ◽  
Multiple Line ◽  
Secondary Ion ◽  
Low Temperature Photoluminescence

ABSTRACTWe have investigated the interface roughness of single thin InP/InAs quantum wells grown by Chemical Beam Epitaxy. We report results of low temperature photoluminescence and secondary ion mass spectroscopy. The interface roughness is characterized by multiple-line photoluminescence spectra and is very sensitive to parameters such as the growth temperature. Details of the interface roughness are discussed based on the shifts of the excitonic energies observed by photoluminescence.

Influence of n-Type Doping Levels on Carrier Lifetime in 4H-SiC Epitaxial Layers

2017 ◽  
Vol 897 ◽  
pp. 238-241 ◽  
Author(s):  
Louise Lilja ◽  
Ildiko Farkas ◽  
Ian Booker ◽  
Jawad ul Hassan ◽  
Erik Janzén ◽  
...  
Keyword(s):  
Low Temperature ◽  
Deep Level Transient Spectroscopy ◽  
Doping Level ◽  
Carrier Lifetime ◽  
Deep Level ◽  
Growth Conditions ◽  
Epitaxial Layers ◽  
Drastic Decrease ◽  
Transient Spectroscopy ◽  
Low Temperature Photoluminescence

In this study we have grown thick 4H-SiC epitaxial layers with different n-type doping levels in the range 1E15 cm-3 to mid 1E18 cm-3, in order to investigate the influence on carrier lifetime. The epilayers were grown with identical growth conditions except the doping level on comparable substrates, in order to minimize the influence of other parameters than the n-type doping level. We have found a drastic decrease in carrier lifetime with increasing n-type doping level. Epilayers were further characterized with low temperature photoluminescence and deep level transient spectroscopy.

Growth of Thick Ge Epilayers on Si(100) Substrates Utilizing Two-Step Approach by Ultrahigh Vacuum Chemical Vapor Deposition

2013 ◽  
Vol 860-863 ◽  
pp. 890-893
Author(s):  
Zhi Wen Zhou ◽  
Yue Zhong Zhang ◽  
Xiao Xia Shen
Keyword(s):  
Chemical Vapor Deposition ◽  
Low Temperature ◽  
Growth Temperature ◽  
Vapor Deposition ◽  
Compressive Strain ◽  
Ultrahigh Vacuum ◽  
Chemical Vapor ◽  
Growth Conditions ◽  
Buffer Layers ◽  
Threading Dislocation

Ge epilayers on low temperature (LT) Ge buffer layers were grown by ultrahigh vacuum chemical vapor deposition using the two-step approach. Effects of the growth temperature and the thickness of the low temperature Ge buffers were studied. It was demonstrated that it was unable to obtain flat LT Ge buffers just through lowering the growth temperature due to the ultraslow grow rate that 3D islands formation couldnt be prohibited. However, the rough LT Ge surface was smoothed by subsequent growth at elevated temperature if the LT Ge layer was thick enough and the compressive strain was relaxed largely, and the detrimental Si-Ge intermixing was effectively prohibited as well. When using proper growth conditions for the low temperature Ge buffer, thick Ge epilayer with a low threading dislocation density and a smooth surface was obtained.

scholarly journals Effects of MOVPE Growth Conditions on GaN Layers Doped with Germanium

2020 ◽  
Author(s):  
Dario Schiavon ◽  
Elżbieta Litwin-Staszewska ◽  
Rafał Jakieła ◽  
Szymon Grzanka ◽  
Piotr Perlin
Keyword(s):  
Growth Rate ◽  
High Temperature ◽  
Low Temperature ◽  
Surface Morphology ◽  
Growth Temperature ◽  
High Growth ◽  
Growth Conditions ◽  
High Growth Rate ◽  
Pit Formation ◽  
Movpe Growth

The effect of growth temperature and precursor flows on the doping level and surface morphology of Ge-doped GaN layers was researched. The results show that germanium is more readily incorporated at low temperature, high growth rate and high V/III ratio, thus revealing a similar behavior to what was previously observed for indium. V-pit formation can be blocked at high temperature but also at low V/III ratio, the latter of which however causing step bunching.

scholarly journals Optimization of MBE Growth Conditions of In0.52Al0.48As Waveguide Layers for InGaAs/InAlAs/InP Quantum Cascade Lasers

Materials ◽  
2019 ◽  
Vol 12 (10) ◽  
pp. 1621 ◽  
Author(s):  
Piotr Gutowski ◽  
Iwona Sankowska ◽  
Tomasz Słupiński ◽  
Dorota Pierścińska ◽  
Kamil Pierściński ◽  
...  
Keyword(s):  
Active Region ◽  
Growth Temperature ◽  
Quantum Cascade Lasers ◽  
Growth Conditions ◽  
Interface Roughness ◽  
Reciprocal Space Mapping ◽  
Mbe Growth ◽  
Quantum Cascade ◽  
Free Material ◽  
Cascade Lasers

We investigate molecular beam epitaxy (MBE) growth conditions of micrometers-thick In0.52Al0.48As designed for waveguide of InGaAs/InAlAs/InP quantum cascade lasers. The effects of growth temperature and V/III ratio on the surface morphology and defect structure were studied. The growth conditions which were developed for the growth of cascaded In0.53Ga0.47As/In0.52Al0.48As active region, e.g., growth temperature of Tg = 520 °C and V/III ratio of 12, turned out to be not optimum for the growth of thick In0.52Al0.48As waveguide layers. It has been observed that, after exceeding ~1 µm thickness, the quality of In0.52Al0.48As layers deteriorates. The in-situ optical reflectometry showed increasing surface roughness caused by defect forming, which was further confirmed by high resolution X-ray reciprocal space mapping, optical microscopy and atomic force microscopy. The presented optimization of growth conditions of In0.52Al0.48As waveguide layer led to the growth of defect free material, with good optical quality. This has been achieved by decreasing the growth temperature to Tg = 480 °C with appropriate increasing V/III ratio. At the same time, the growth conditions of the cascade active region of the laser were left unchanged. The lasers grown using new recipes have shown lower threshold currents and improved slope efficiency. We relate this performance improvement to reduction of the electron scattering on the interface roughness and decreased waveguide absorption losses.

AlInAs Band Gap Modulations Observed by Tem and Optical Measurements

1995 ◽  
Vol 417 ◽  
Author(s):  
E. Bearzi ◽  
T. Benyattou ◽  
C. Bru-Chevallier ◽  
G. Guillot ◽  
J. C. Harmand ◽  
...  
Keyword(s):  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
Optical Properties ◽  
Low Temperature ◽  
Band Gap ◽  
Growth Temperature ◽  
Optical Measurements ◽  
Mbe Growth ◽  
Composition Modulation ◽  
Transmission Electron

AbstractAt a low MBE growth temperature (400°C), an anisotropic composition modulation has been observed by Transmission Electron Microscopy (TEM) on AIlnAs layers. Optical measurements have been performed on these samples and compared with classical AllnAs grown at 530°C. We show the clustering “organization” on the low temperature layers and we propose some hypothesis to explain the composition modulation effects on the AlInAs optical properties.

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