Effect of Substrate Misonrentation on Ordering in Ga0.5In0.5P

1994 ◽  
Vol 340 ◽  
Author(s):  
L.C. Su ◽  
I.H. Ho ◽  
G.B. Stringfellow ◽  
Y. Leng ◽  
C.C. Williams
Keyword(s):  
Growth Rate ◽  
Misorientation Angle ◽  
Growth Temperature ◽  
Electrostatic Force ◽  
Surface States ◽  
Energy Difference ◽  
Growth Conditions ◽  
Disordered Materials ◽  
Transmission Electron ◽  
Degree Of Order

ABSTRACTOrdering produced in Ga0.5ln0.5P epitaxial layers grown by OMVPE can be controlled by variations in the substrate misorientation as well as the growth temperature and the growth rate. The ordering produced at a growth temperature of 620°C and a relatively low growth rate of 0.5 μm/hr is found to depend strongly on both the direction and angle of substrate misorientation. Transmission electron microscope images and transmission electron diffraction (TED) patterns as well as electrostatic force microscopy (EFM) and photoluminescence (PL) has been studied for misorientation angles of 0, 3, 6, and 9° from (001) toward the (111)B, (111)A, and [010] directions in the lattice. Misorientation in the (111)B direction (to produce [110] steps) increases ordering for angles of up to approximately 4°. Increasing the misorientation angle in the (111)A direction actually leads to a decrease in the degree of order observed. Misorientation in the [010] direction also decreases the degree of order, although the effect is much less than observed for misorientation in the (111)A direction. The most highly ordered material produced under these growth conditions is for a misorientation angle of 3° in the (111)A direction. Increasing the growth temperature to 720°C produces completely disordered material. This wide variation in ordering behavior has allowed the growth of an order/disorder heterostructure for a substrate misorientation of 3° in the (111)A direction. The heterostructure consists of a Ga0.52In0.48P layer grown at 740°C followed by an ordered layer grown at 620°C. The x-ray diffraction results show that both layers are precisely lattice-matched to the GaAs substrate. TED patterns show that the first layer is completely disordered and the top layer is highly ordered, with only a single variant. EFM images of the order/disorder heterostructure show a pronounced contrast at the interface, attributed to the large difference in the nature of the surface states in the ordered and disordered materials. The 10 K PL spectrum consists of two sharp and distinct peaks at 1.995 and 1.830 eV from the disordered and ordered materials, respectively. The peak separation represents the largest energy difference between ordered and disordered materials reported to date. Such heterostructures may be useful for photonic devices.

Structure and Field Electron Emission of Carbon Nanotubes Dependent on Growth Temperature

2002 ◽  
Vol 728 ◽  
Author(s):  
Yoon Huh ◽  
Jeong Yong Lee ◽  
Tae Jae Lee ◽  
Seung Chul Lyu ◽  
Cheol Jin Lee
Keyword(s):  
Electron Microscopy ◽  
Carbon Nanotubes ◽  
Growth Rate ◽  
Growth Temperature ◽  
Silicon Oxide ◽  
Structural Characteristics ◽  
Average Diameter ◽  
Crystalline Perfection ◽  
Thermal Cvd ◽  
Transmission Electron

AbstractThis present work deals with the temperature dependence on the growth and structure of CNTs grown by thermal CVD. The vertically aligned CNTs are synthesized on iron (Fe)-deposited silicon oxide (SiO2) substrate by thermal CVD using acetylene gas at temperatures in the range 750-950°C. Configuration and structural characteristics of CNTs have been investigated using scanning electron microscopy (SEM) and transmission electron microscopy (TEM). As the growth temperature increases from 750 to 950°C, the growth rate and the average diameter increase while the density decreases by a factor of about 2. TEM images show that the relative amount of crystalline graphitic sheets increases with increasing the growth temperature and a higher degree of crystalline perfection can be achieved at 950°C. The HRTEM images reveal consistently that the degree of crystalline perfection increases progressively as the growth temperature increases. This result demonstrates that the growth rate, diameter, density, and crystallinity of carbon nanotubes can be controlled with the growth temperature.

Selective Epitaxy of AlxGa1−x as and AlxGal−x as Based Structures

1989 ◽  
Vol 158 ◽  
Author(s):  
M.S. Goorsky ◽  
T.F. Kuech ◽  
R. Potemski
Keyword(s):  
Growth Rate ◽  
Phase Composition ◽  
Quantum Wells ◽  
Gas Phase ◽  
Growth Temperature ◽  
Alloy Composition ◽  
Growth Conditions ◽  
Selective Epitaxy ◽  
Strong Function ◽  
Growth Temperature Range

ABSTRACTSelective epitaxy of AlxGa1−x As by MOVPE was accomplished using diethyl gallium chloride and diethyl aluminum chloride as the metalorganic precursors. Selective epitaxy was achieved for Al containing compounds under certain growth conditions, but AlAs growth was not selective. Quantum wells were selectively grown on masked substrates and unpatterned GaAs wafers; QW luminescence was observed from all samples. Additionally, near gap luminescence was observed from AlxGa1−x, As heterostructures over the entire 550 °C - 850 °C growth temperature range. The ternary alloy composition was found to be a strong function of the gas phase composition and growth temperature. A simple thermodynamic model explained the dependence of growth rate and composition on these parameters.

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.

Effect of the Growth Conditions on the Crystal Quality in Solution Growth of SiC Using Cr Solvent without Molten Si

2018 ◽  
Vol 924 ◽  
pp. 35-38 ◽  
Author(s):  
Koki Suzuki ◽  
Koang Yong Hyun ◽  
Toshinori Taishi
Keyword(s):  
Growth Rate ◽  
Growth Temperature ◽  
Growth Conditions ◽  
Solution Growth ◽  
Crystal Quality ◽  
Liquid Height

We have succeeded in solution growth of SiC from Cr solvent without Si using ceramic SiC as the SiC source. The effect of the growth conditions, such as the liquid height in the crucible, on the crystal quality in solution growth of SiC from Cr solvent was investigated. For a liquid height in the crucible of up to 10 mm, the growth rate increases with increasing liquid height and the SiC crystals are a single polytype, while the growth rate decreases and the crystals are polycrystalline for a liquid height above 10 mm. In the former case, the balance between dissolution and transportation of the solute are comparable. The latter case is expected to be transportation limited because transportation of free C and Si atoms is inhibited by excrescent crystals in solution and the increase in the distance for solute transportation. In addition, a higher growth temperature leads to growth of only 4H-SiC.

Stress engineering using AlN/GaN superlattices for epitaxy of GaN on 200 mm Si wafers

2014 ◽  
Vol 1736 ◽  
Author(s):  
Jie Su ◽  
Eric A. Armour ◽  
Balakrishnan Krishnan ◽  
Soo Min Lee ◽  
George D. Papasouliotis
Keyword(s):  
Growth Rate ◽  
Tensile Stress ◽  
Growth Temperature ◽  
Growth Conditions ◽  
Stress Control ◽  
Stress Engineering ◽  
Constant Period

ABSTRACTStress control using AlN/GaN superlattices (SLs) for epitaxy of GaN on 200 mm Si (111) substrates is reported. Crack-free 2 μm GaN layers were grown over structures containing 50 to 100 pairs of 3-5 nm AlN/10-30 nm GaN SLs. Compressive and tensile stress can be precisely adjusted by changing the thickness of the AlN and GaN layers in the SLs. For a constant period thickness, the effects of growth conditions, such as growth rate of GaN, V/III ratio during AlN growth, and growth temperature, on wafer stress were investigated.

Dependence of the Growth of Al2O3 Films on the Growth Conditions in the ALE-Like Process

1992 ◽  
Vol 284 ◽  
Author(s):  
Jia-Fa Fan ◽  
Koichi Toyoda
Keyword(s):  
Thin Films ◽  
Growth Rate ◽  
Electrical Properties ◽  
Growth Temperature ◽  
Chemical Bonding ◽  
Bonding Strength ◽  
Molecular Beams ◽  
Growth Conditions ◽  
Al2o3 Films

ABSTRACTEffects of the growth conditions on the growth and the quality of thin films of Al2O3 were investigated in the ALE-like process. It has been found that the growth rate remains nearly independent of the growth conditions when the pulse heights are 80–120 mTorr and 20–160 mTorr for H2O2 and TMA respectively, the pulse duration longer than 0.3 s, the base pressure below 1 mTorr, and the growth temperature higher than 150°C. Also, we found that the density, the chemical bonding strength, and the electrical properties improved markedly with raising the growth temperature although the growth rate remained nearly constant. In addition, area-selective growth and partly polycrystalline films were favorably obtained by using pulsed molecular beams of TMA and H2O2 in the growth.

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

Materials ◽  
2021 ◽  
Vol 14 (2) ◽  
pp. 354
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 flow 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.

Influence of MBE Growth Conditions on Dislocation Densities of GaAs/Ge Epilayers Grown on Silicon Substrates

1985 ◽  
Vol 43 ◽  
pp. 364-365
Author(s):  
K.M. Hones ◽  
P. Sheldon ◽  
B.G. Yacobi ◽  
A. Mason
Keyword(s):  
High Efficiency ◽  
Lattice Mismatch ◽  
Low Cost ◽  
Growth Conditions ◽  
Nonradiative Recombination ◽  
Device Structure ◽  
Si Substrates ◽  
Transmission Electron ◽  
Dislocation Densities ◽  
Dislocation Type

There is increasing interest in growing epitaxial GaAs on Si substrates. Such a device structure would allow low-cost substrates to be used for high-efficiency cascade- junction solar cells. However, high-defect densities may result from the large lattice mismatch (∼4%) between the GaAs epilayer and the silicon substrate. These defects can act as nonradiative recombination centers that can degrade the optical and electrical properties of the epitaxially grown GaAs. For this reason, it is important to optimize epilayer growth conditions in order to minimize resulting dislocation densities. The purpose of this paper is to provide an indication of the quality of the epitaxially grown GaAs layers by using transmission electron microscopy (TEM) to examine dislocation type and density as a function of various growth conditions. In this study an intermediate Ge layer was used to avoid nucleation difficulties observed for GaAs growth directly on Si substrates. GaAs/Ge epilayers were grown by molecular beam epitaxy (MBE) on Si substrates in a manner similar to that described previously.

Diffraction from arrays of antiphase boundaries in ordered III-V alloys

1987 ◽  
Vol 45 ◽  
pp. 312-313
Author(s):  
T. S. Kuan
Keyword(s):  
High Surface ◽  
Growth Conditions ◽  
Ternary Alloys ◽  
Local Growth ◽  
Antiphase Boundaries ◽  
Surface Mobility ◽  
Ordered Phases ◽  
Diffraction Patterns ◽  
Atomically Flat ◽  
Degree Of Order

Recent electron diffraction studies have found ordered phases in AlxGa1-xAs, GaAsxSb1-x, and InxGa1-xAs alloy systems, and these ordered phases are likely to be found in many other III-V ternary alloys as well. The presence of ordered phases in these alloys was detected in the diffraction patterns through the appearance of superstructure reflections between the Bragg peaks (Fig. 1). The ordered phase observed in the AlxGa1-xAs and InxGa1-xAs systems is of the CuAu-I type, whereas in GaAsxSb1-x this phase and a chalcopyrite type ordered phase can be present simultaneously. The degree of order in these alloys is strongly dependent on the growth conditions, and during the growth of these alloys, high surface mobility of the depositing species is essential for the onset of ordering. Thus, the growth on atomically flat (110) surfaces usually produces much stronger ordering than the growth on (100) surfaces. The degree of order is also affected by the presence of antiphase boundaries (APBs) in the ordered phase. As shown in Fig. 2(a), a perfectly ordered In0.5Ga0.5As structure grown along the <110> direction consists of alternating InAs and GaAs monolayers, but due to local growth fluctuations, two types of APBs can occur: one involves two consecutive InAs monolayers and the other involves two consecutive GaAs monolayers.

Defect morphology in thick relaxed layers of InGaAs on GaAs

1990 ◽  
Vol 48 (4) ◽  
pp. 668-669
Author(s):  
R H Dixon ◽  
P Kidd ◽  
P J Goodhew
Keyword(s):  
Electron Microscopy ◽  
Surface Morphology ◽  
Growth Conditions ◽  
X Ray Diffraction ◽  
Double Crystal ◽  
Strained Layers ◽  
Good Surface ◽  
Transmission Electron ◽  
Device Structures ◽  
Surface Morphologies

Thick relaxed InGaAs layers grown epitaxially on GaAs are potentially useful substrates for growing high indium percentage strained layers. It is important that these relaxed layers are defect free and have a good surface morphology for the subsequent growth of device structures.3μm relaxed layers of InxGa1-xAs were grown on semi - insulating GaAs substrates by Molecular Beam Epitaxy (MBE), where the indium composition ranged from x=0.1 to 1.0. The interface, bulk and surface of the layers have been examined in planar view and cross-section by Transmission Electron Microscopy (TEM). The surface morphologies have been characterised by Scanning Electron Microscopy (SEM), and the bulk lattice perfection of the layers assessed using Double Crystal X-ray Diffraction (DCXRD).The surface morphology has been found to correlate with the growth conditions, with the type of defects grown-in to the layer (e.g. stacking faults, microtwins), and with the nature and density of dislocations in the interface.

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