Formation of Heterogeneous Thickness Modulations During Epitaxial Growth of LPCVD-Si1−xGex/Si Quantum Well Structures

1992 ◽  
Vol 263 ◽  
Author(s):  
L. Vescan ◽  
W. Jäger ◽  
C. Dieker ◽  
K. Schmidt ◽  
A. Hartmann ◽  
...  
Keyword(s):  
Quantum Well ◽  
Three Dimensional ◽  
Chemical Vapor ◽  
Misfit Dislocations ◽  
Preferential Growth ◽  
Quantum Well Structures ◽  
Transmission Electron ◽  
Pressure Chemical ◽  
Dimensional Growth ◽  
Photoluminescence Studies

ABSTRACTTransmission electron microscopy and photoluminescence studies were performed to determine the critical thickness for generation of misfit dislocations in Sil-xGex layers grown by low pressure chemical vapor deposition. Above a certain Ge content the transition from two dimensional to three-dimensional growth occurs before generation of misfit dislocations. For instance, for x ∼0.3 and a substrate temperature around 700°C island formation was observed to start at 1.8 nm. The formation of islands is attributed to the preferential growth of SiGe in areas with less lattice strain. Islands were observed to broaden the exciton photoluminescence of the quantum well structures.

Growth of SiGe/Si quantum well structures by atmospheric pressure chemical vapor deposition

1993 ◽  
Vol 22 (3) ◽  
pp. 303-308 ◽  
Author(s):  
D. A. Grützmacher ◽  
T. O. Sedgwick ◽  
A. Zaslavsky ◽  
A. R. Powell ◽  
R. A. Kiehl ◽  
...  
Keyword(s):  
Chemical Vapor Deposition ◽  
Quantum Well ◽  
Vapor Deposition ◽  
Atmospheric Pressure ◽  
Chemical Vapor ◽  
Quantum Well Structures ◽  
Pressure Chemical

Thermal Stability Of SiGe/Si Quantum Well Structures Grown By APCVD

1998 ◽  
Vol 533 ◽  
Author(s):  
Q. X. Zhao ◽  
O. Nur ◽  
U. Södervall ◽  
C. J. Patel ◽  
M. Willandera ◽  
...  
Keyword(s):  
Quantum Well ◽  
Atmospheric Pressure ◽  
Annealing Temperature ◽  
Secondary Ion Mass Spectrometry ◽  
Chemical Vapor ◽  
Quantum Well Structures ◽  
Pressure Chemical ◽  
Different Temperatures ◽  
Secondary Ion ◽  
Thermal Stability Of

AbstractSingle and double Si1-xGexx/Si quantum well (QW) structures, which were grown by atmospheric pressure chemical vapor deposition (APCVD), are characterized by photoluminescence and secondary ion mass spectrometry. Systematic post-growth annealing treatments were carried out at temperatures between 600°C and 1100°C in pure N2 ambient. The interdiffusion between the Si layer and the Si1-xGex, well layers occurs at the annealing temperature around 900°C. The diffusion coefficient is deduced at different temperatures from SIMS measurements for single QW structures. The activation energy is about 3.9 eV in the temperature range between 950°C and 1100°C. The double QW structures show a similar value, but the accurate value is more difficult to obtain because it is more complicated to analyze the SIMS profile of the double QW structures. The intensity of the exciton recombination related to carriers confined in the double QW structures decreases with increasing annealing temperatures and becomes strongly suppressed at 750°C. When the annealing temperature is increased further, the intensity of the QW emission recovers. The results indicate that nonradiative centers were generated at annealing temperature of about 750°C

Structural and Optical Properties of AlGaN/GaN Quantum-Well Structures Grown by MOCVD on Sapphire

1996 ◽  
Vol 449 ◽  
Author(s):  
R. Niebuhr ◽  
K. H. Bachem ◽  
D. Behr ◽  
C. Hoffmann ◽  
U. Kaufmann ◽  
...  
Keyword(s):  
Quantum Well ◽  
Quantum Wells ◽  
Chemical Vapor ◽  
Interface Roughness ◽  
Organic Chemical ◽  
Quantum Well Structures ◽  
Force Microscopy ◽  
Transmission Electron ◽  
Metal Organic ◽  
Step Flow Growth

ABSTRACTAlGaN/GaN single quantum wells (QW) have been grown on 2” sapphire substrates (c-plane) by metal-organic chemical vapor deposition (MOCVD). The well width was varied between 20 and 40 Å for barriers containing 4 % and 16 % of aluminium. Cathodoluminescence (CL) and Photoluminescence (PL) spectra of the samples show, as expected, a shift of the quantum well emission to higher energies with decreasing well width, whereas the barrier luminescence stays at constant energy. Examination of the QWs by resonant Raman spectroscopy tuned to the gap of the well, clearly shows the GaN A1(LO) phonon besides the AlGaN A1(LO) phonon from the barrier. For a well width of 20 Å we observe a shift of the A1(LO) GaN phonon indicating a certain degree of intermixing at the GaN/AlGaN interface. Atomic Force Microscopy (AFM) reveals that the layers are growing in a 2-dimensional step flow growth mode with step heights of 3 and 6 Å corresponding to mono- and biatomic steps. High Resolution Transmission Electron Microscopy (HRTEM) micrographs of the 40 Å well show a very low interface roughness of 1–2 atomic layers.

Substrate Effects on the Kinetics of Solid Phase Crystallization In a-Si

1991 ◽  
Vol 230 ◽  
Author(s):  
L. Haji ◽  
P. Joubert ◽  
M. Guendouz ◽  
N. Duhamel ◽  
B. Loisel
Keyword(s):  
Indium Tin Oxide ◽  
Solid Phase ◽  
Three Dimensional ◽  
Chemical Vapor ◽  
X Ray Diffraction ◽  
Solid Phase Crystallization ◽  
Transmission Electron ◽  
Pressure Chemical ◽  
Drastic Effect ◽  
Kinetics Of

AbstractThe effect of substrate nature on the solid phase crystallization at 600 °C of a-Si deposited by low pressure chemical vapor deposition is investigated by x-ray diffraction and transmission electron microscopy. The nucleation rate varies slightly resulting to a weak variation in the final grain sizes as a function of the substrate type. In all cases the grain growth mode is found to be three dimensional. In contrary, a drastic effect of the substrate is observed for films deposited by plasma enhanced CVD. Fast crystallization is obtained on indium tin oxide (ITO) resulting to small grain poly-Si, whereas the crystallization is retarded on glass leading to an increase in the grain size.

Misfit dislocations in green-emitting InGaN/GaN quantum well structures

2005 ◽  
Vol 892 ◽  
Author(s):  
Pedro MFJ Costa ◽  
Ranjan Datta ◽  
Menno J Kappers ◽  
Mary E Vickers ◽  
Colin J Humphreys
Keyword(s):  
Quantum Well ◽  
Strain Relaxation ◽  
Vapour Phase ◽  
Misfit Dislocations ◽  
Single Quantum Well ◽  
Vapour Phase Epitaxy ◽  
Quantum Well Structures ◽  
Transmission Electron ◽  
Metal Organic ◽  
Organic Vapour

AbstractMisfit dislocations (MDs) have been observed using transmission electron microscopy (TEM) in InGaN/GaN quantum well (MQW) structures grown under different metal-organic vapour phase epitaxy (MOVPE) regimes and with In-contents equal to or higher than 20%. These dislocations are even observed in a single quantum well 3 nm thick with an In-content of 22%. Conversely, no MDs were observed in QW structures with an In-content of 16%. The presence of MDs in the QW stack leads to strain relaxation which has been confirmed in the indium-rich structures by high resolution X-ray diffraction (HRXRD).

Heteroepitaxial Nucleation and Growth of Ge ON Si(100) Surfaces Using Remote Plasma Enhanced Chemical Vapor Deposition

1988 ◽  
Vol 116 ◽  
Author(s):  
R.A. Rudder ◽  
S.V. Hattangady ◽  
D.J. Vitkavage ◽  
R.J. Markunas
Keyword(s):  
Chemical Vapor Deposition ◽  
Vapor Deposition ◽  
Photoelectron Spectroscopy ◽  
Three Dimensional ◽  
Chemical Vapor ◽  
Layer By Layer ◽  
Heteroepitaxial Growth ◽  
Remote Plasma ◽  
Dimensional Growth ◽  
Diffraction Patterns

Heteroepitaxial growth of Ge on Si(100) has been accomplished using remote plasma enhanced chemical vapor deposition at 300*#x00B0;C. Reconstructed surfaces with diffraction patterns showing non-uniform intensity variations along the lengths of the integral order streaks are observed during the first 100 Å of deposit. This observation of an atomically rough surface during the initial stages of growth is an indication of three-dimensional growth. As the epitaxial growth proceeds, the diffraction patterns become uniform with extensive streaking on both the integral and fractional order streaks. Subsequent growth, therefore, takes place in a layer-by-layer, two-dimensional mode. X-ray photoelectron spectroscopy of the early nucleation stages, less than 80 Å, show that there is uniform coverage with no evidence of island formation.

Growth of Si1−xGex, Strained Layers Using Atmospheric-Pressure CVD

1991 ◽  
Vol 220 ◽  
Author(s):  
F. Namavar ◽  
J. M. Manke ◽  
E. P. Kvam ◽  
M. M. Sanfacon ◽  
C. H. Perry ◽  
...  
Keyword(s):  
Atmospheric Pressure ◽  
Defect Density ◽  
Chemical Vapor ◽  
Good Growth ◽  
X Ray Diffraction ◽  
Strained Layers ◽  
Dislocation Glide ◽  
Transmission Electron ◽  
Pressure Chemical ◽  
Film Defect

ABSTRACTThe objective of this paper is to demonstrate the epitaxial growth of SiGe strained layers using atmospheric-pressure chemical vapor deposition (APCVD). We have grown SiGe layers with various thicknesses and Ge concentrations at temperatures ranging from 800–1000°C. The samples were studied using a variety of methods, including transmission electron microscopy (TEM), high resolution X-ray diffraction (HRXRD) and Raman spectroscopy (RS). Both HRXRD and RS results indicate that samples with about 10% Ge and a thickness of about 1000 Å are almost fully strained. TEM analyses of these samples indicate a film defect density less than 105/cm2. SIMS results indicate that the oxygen concentration in the epitaxial layers is lower than that found in CZ substrates.Our analyses also indicate that as-grown epitaxial Ge layers several microns thick have a defect density less than 107/cm2. The relatively low defect density in both SiGe and Ge layers grown on Si has been attributed to far higher dislocation glide velocity at the relatively elevated growth temperatures employed in CVD and to very good growth cleanliness.

scholarly journals Ge / SiGe Multi Quantum Well Fabrication by Using Reduced Pressure Chemical Vapor Deposition

2019 ◽  
Author(s):  
Y. Yamamoto ◽  
O. Skibitzki ◽  
M.A. Schubert ◽  
M. Scuderi ◽  
F. Reichmann ◽  
...  
Keyword(s):  
Chemical Vapor Deposition ◽  
Quantum Well ◽  
Vapor Deposition ◽  
Chemical Vapor ◽  
Reduced Pressure ◽  
Pressure Chemical ◽  
Multi Quantum Well

Fabrication and electrochemical characterization of super-capacitor based on three-dimensional composite structure of graphene and a vertical array of carbon nanotubes

2018 ◽  
Vol 52 (22) ◽  
pp. 3039-3044 ◽  
Author(s):  
Daniel Choi ◽  
Eui-Hyeok Yang ◽  
Waqas Gill ◽  
Aaron Berndt ◽  
Jung-Rae Park ◽  
...  
Keyword(s):  
Carbon Nanotubes ◽  
Vapor Deposition ◽  
Composite Structure ◽  
Graphene Layer ◽  
Three Dimensional ◽  
Chemical Vapor ◽  
Deposition Process ◽  
Silicon Substrates ◽  
Vertical Array ◽  
Pressure Chemical

We have demonstrated a three-dimensional composite structure of graphene and carbon nanotubes as electrodes for super-capacitors. The goal of this study is to fabricate and test the vertically grown carbon nanotubes on the graphene layer acting as a spacer to avoid self-aggregation of the graphene layers while realizing high active surface area for high energy density, specific capacitance, and power density. A vertical array of carbon nanotubes on silicon substrates was grown by a low-pressure chemical vapor deposition process using anodized aluminum oxide nanoporous template fabricated on silicon substrates. Subsequently, a graphene layer was grown by another low-pressure chemical vapor deposition process on top of a vertical array of carbon nanotubes. The Raman spectra confirmed the successful growth of carbon nanotubes followed by the growth of high-quality graphene. The average measured capacitance of the three-dimensional composite structure of graphene-carbon nanotube was 780 µFcm−2 at 100 mVs−1.

Photoluminescence and Transmission Electron Microscopy Methods for Characterization of Super-Multiperiod A3B5 Quantum Well Structures

2019 ◽  
Vol 53 (14) ◽  
pp. 1914-1917 ◽  
Author(s):  
L. I. Goray ◽  
E. V. Pirogov ◽  
E. V. Nikitina ◽  
E. V. Ubyivovk ◽  
L. G. Gerchikov ◽  
...  
Keyword(s):  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
Quantum Well ◽  
Quantum Well Structures ◽  
Transmission Electron
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