A New Approach to Grow Strain-Free GaAs on Si

1990 ◽  
Vol 202 ◽  
Author(s):  
Hyunchul Sohn ◽  
Eicke R. Weber ◽  
Jay Tu ◽  
Shyh Wang
Keyword(s):  
Residual Strain ◽  
Lattice Mismatch ◽  
Gaas Layer ◽  
Threading Dislocations ◽  
New Approach ◽  
Thermally Induced ◽  
Si Substrates ◽  
Growth Area ◽  
The Difference ◽  
Substrate Patterning

ABSTRACTThe major problems of the GaAs/Si heteroepitaxy are the high density of threading dislocations and the high residual strain in the GaAs epilayers. The residual strain in the epilayer is attributed to the difference in contraction during cooling down from the growth temperature. It was reported previously that the residual stress in GaAs epilayer could be reduced by reducing the growth area using substrate patterning. In this paper, we report a new approach to grow strain- free GaAs layer on Si substrates. The residual strain in GaAs/Si is tensile in nature, therefore we attempted to compensate this thermally induced strain by compressive lattice mismatched strain. The thermally induced strain in the GaAs layer was successfully compensated by the lattice- mismatch induced strain using In0.032Ga0.968As. By that method, we could grow thin strain- free GaAs layers on Si without patterning. The strain relieving effect was confirmed by photoluminescence experiment.

MOCVD Growth of III-V Compounds on Si Using Strained Superlattices

1986 ◽  
Vol 67 ◽  
Author(s):  
Shiro Sakai ◽  
Tetsuo Soga ◽  
Masanari Takeyasu ◽  
Masayoshi Umeno
Keyword(s):  
Electronic Properties ◽  
Intermediate Layer ◽  
Lattice Mismatch ◽  
Gaas Layer ◽  
X Ray Diffraction ◽  
X Ray ◽  
Double Heterostructure ◽  
Si Substrates ◽  
Mocvd Growth ◽  
Structural And Electronic Properties

ABSTRACTGaAs and GaAsP with the entire compositional range are grow on Si using an intermediate layer of GaAsP strained superlattices to relax the lattice mismatch. The orientation of the overgrown GaAs layer is found to be determined by the direction of the off-angle of the Si (100) surface. The grown layers are characterized by photoluminescence, x-ray diffraction, electro reflectance and DLTS. GaAs/GaAlAs double heterostructure lasers and GaAsP visible LED's are fabricated on Si substrates. The structural and electronic properties of the grown layers and the device performances are reported in this paper.

Defect Reduction by Thermal Cyclic Growth in GaAs Grown on Si by Movpe

1993 ◽  
Vol 325 ◽  
Author(s):  
W. KÜrner ◽  
R. Dieter ◽  
K. Zieger ◽  
F. Goroncy ◽  
A. DÖrnen ◽  
...  
Keyword(s):  
Thermal Expansion ◽  
Thermal Stress ◽  
Dislocation Density ◽  
Lattice Mismatch ◽  
Gaas Layer ◽  
Defect Reduction ◽  
Thermal Expansion Coefficients ◽  
Related Defect ◽  
Expansion Coefficients ◽  
The Difference

AbstractThe growth of GaAs epilayers on Si should combine the advantages of both materials. The lattice mismatch and the difference in thermal expansion coefficients, however, result in the yet unsolved problems of high dislocation density and thermal stress in the GaAs layer. Recently, considerable improvements have been achieved by a ‘thermal cyclic growth’ (TCG) process. In this study we focus on the reduction of high defect concentration and dislocation density. The improvement of the epilayer quality is verified by DLTS, PL and DCXD. Results of TEM and DLTS measurements lead to the identification of a dislocation related defect.

Structural and Electrical Properties of Heteroepitaxial HgCdTe/CdZnTe/GaAs/Si

1989 ◽  
Vol 161 ◽  
Author(s):  
S.M. Johnson ◽  
W.L. Ahlgren ◽  
M. H. Kalisher ◽  
J. B. James ◽  
W. J. Hamilton
Keyword(s):  
Electrical Properties ◽  
Hall Effect ◽  
Lattice Mismatch ◽  
Biaxial Tension ◽  
Gaas Layer ◽  
X Ray ◽  
Si Substrates ◽  
Structural And Electrical Properties ◽  
Before And After ◽  
Hall Effect Measurements

ABSTRACTThe structural and electrical properties of heteroepitaxial HgCdTe/CdZnTe/GaAs/Si were evaluated using high-resolution x-ray diffraction techniques and Hall-effect measurements as a function of temperature. Significant tilting of the layers was found for both {100} and {111} CdZnTe layers grown on misoriented {100}GaAs/Si substrates, consistent with the interpretation of a low-angle tilt boundary being formed at the interface to relieve the large lattice mismatch between the layers. The GaAs layer is in a state of biaxial tension before and after the growth of the CdZnTe layers. The x-ray FWHM of HgCdTe layers grown by LPE on these substrates was found to be reduced from that of the MOCVD-grown CdZnTe buffer layer due to both an annealing effect during LPE growth and to the increased distance of layer surface from the defective CdZnTe/GaAs interface. Hall-effect mobility for {100}HgCdTe layers was nearly identical to that of layers grown on bulk CdZnTe substrates. High-quality heterojunction infrared detectors have been fabricated using these materials.

Defects in β-SiC thin films grown on α-SiC substrates

1988 ◽  
Vol 46 ◽  
pp. 568-569
Author(s):  
Karren L. More
Keyword(s):  
Thin Films ◽  
Semiconductor Device ◽  
Lattice Mismatch ◽  
Chemical Vapor ◽  
Substrate Material ◽  
Growth Interface ◽  
Si Substrates ◽  
Thermal Expansion Coefficients ◽  
Device Applications ◽  
Expansion Coefficients

Beta-SiC is an ideal candidate material for use in semiconductor device applications. Currently, monocrystalline β-SiC thin films are epitaxially grown on {100} Si substrates by chemical vapor deposition (CVD). These films, however, contain a high density of defects such as stacking faults, microtwins, and antiphase boundaries (APBs) as a result of the 20% lattice mismatch across the growth interface and an 8% difference in thermal expansion coefficients between Si and SiC. An ideal substrate material for the growth of β-SiC is α-SiC. Unfortunately, high purity, bulk α-SiC single crystals are very difficult to grow. The major source of SiC suitable for use as a substrate material is the random growth of {0001} 6H α-SiC crystals in an Acheson furnace used to make SiC grit for abrasive applications. To prepare clean, atomically smooth surfaces, the substrates are oxidized at 1473 K in flowing 02 for 1.5 h which removes ∽50 nm of the as-grown surface. The natural {0001} surface can terminate as either a Si (0001) layer or as a C (0001) layer.

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.

Anisotropy of interfacial defects in the initial stage of MOVPE GaAs growth On Si

1990 ◽  
Vol 48 (4) ◽  
pp. 592-593
Author(s):  
C. Vannuffel ◽  
C. Schiller ◽  
J. P. Chevalier
Keyword(s):  
Early Stage ◽  
Threading Dislocations ◽  
Mbe Growth ◽  
Detailed Mechanism ◽  
Si Substrates ◽  
Initial Stage ◽  
Interfacial Defects ◽  
Interfacial Dislocations ◽  
Step Growth ◽  
Essential Problem

Recently, interest has focused on the epitaxy of GaAs on Si as a promising material for electronic applications, potentially for integration of optoelectronic devices on silicon wafers. The essential problem concerns the 4% misfit between the two materials, and this must be accommodated by a network of interfacial dislocations with the lowest number of threading dislocations. It is thus important to understand the detailed mechanism of the formation of this network, in order to eventually reduce the dislocation density at the top of the layers.MOVPE growth is carried out on slightly misoriented, (3.5°) from (001) towards , Si substrates. Here we report on the effect of this misorientation on the interfacial defects, at a very early stage of growth. Only the first stage, of the well-known two step growth process, is thus considered. Previously, we showed that full substrate coverage occured for GaAs thicknesses of 5 nm in contrast to MBE growth, where substantially greater thicknesses are required.

Inter-country inequality as a dynamic process and the problem of post-industrial development

2018 ◽  
pp. 5-29 ◽  
Author(s):  
L. M. Grigoryev ◽  
V. A. Pavlyushina
Keyword(s):  
Economic Growth ◽  
Political Institutions ◽  
Industrial Development ◽  
Modern World ◽  
New Approach ◽  
Development Level ◽  
The World ◽  
Long Time ◽  
The Difference ◽  
Post Industrial

The phenomenon of economic growth is studied by economists and statisticians in various aspects for a long time. Economic theory is devoted to assessing factors of growth in the tradition of R. Solow, R. Barrow, W. Easterly and others. During the last quarter of the century, however, the institutionalists, namely D. North, D. Wallis, B. Weingast as well as D. Acemoglu and J. Robinson, have shown the complexity of the problem of development on the part of socioeconomic and political institutions. As a result, solving the problem of how economic growth affects inequality between countries has proved extremely difficult. The modern world is very diverse in terms of development level, and the article offers a new approach to the formation of the idea of stylized facts using cluster analysis. The existing statistics allows to estimate on a unified basis the level of GDP production by 174 countries of the world for 1992—2016. The article presents a structured picture of the world: the distribution of countries in seven clusters, different in levels of development. During the period under review, there was a strong per capita GDP growth in PPP in the middle of the distribution, poverty in various countries declined markedly. At the same time, in 1992—2016, the difference increased not only between rich and poor groups of countries, but also between clusters.

Words are constructions, too: A construction-based approach to English ablaut reduplication

Linguistics ◽  
2020 ◽  
Vol 58 (6) ◽  
pp. 1701-1735
Author(s):  
Jeroen van de Weijer ◽  
Weiyun Wei ◽  
Yumeng Wang ◽  
Guangyuan Ren ◽  
Yunyun Ran
Keyword(s):  
New Approach ◽  
The Difference

AbstractIn this article we present a new approach to words of the type zigzag, chitchat, etc. in English. Such words form a formal (phonological) and functional (semantic) pattern in English. We argue that this pattern should be analysed in a construction-based approach, which has clear advantages over other approaches, e.g. analyses involving extragrammaticality or a synchronically productive reduplication process. We propose to extend the construction-based approach beyond its original scope (syntactic constructions) to words that may even no longer be morphologically complex. Finally, we make a tentative suggestion about how the difference between productive and unproductive patterns could be captured in the construction-based approach.

Optical and structural prorerties of InAs epilayer on graded InGaAs

2001 ◽  
Vol 696 ◽  
Author(s):  
Gu Hyun Kim ◽  
Jung Bum Choi ◽  
Joo In Lee ◽  
Se-Kyung Kang ◽  
Seung Il Ban ◽  
...  
Keyword(s):  
Molecular Beam Epitaxy ◽  
Residual Strain ◽  
Molecular Beam ◽  
Lattice Mismatch ◽  
Peak Position ◽  
Excitation Intensity ◽  
Total Thickness ◽  
Ingaas Layer ◽  
X Ray Diffraction ◽  
X Ray

AbstractWe have studied infrared photoluminescence (PL) and x-ray diffraction (XRD) of 400 nm and 1500 nm thick InAs epilayers on GaAs, and 4 nm thick InAs on graded InGaAs layer with total thickness of 300 nm grown by molecular beam epitaxy. The PL peak positions of 400 nm, 1500 nm and 4 nm InAs epilayer measured at 10 K are blue-shifted from that of InAs bulk by 6.5, 4.5, and 6 meV, respectively, which can be largely explained by the residual strain in the epilayer. The residual strain caused by the lattice mismatch between InAs and GaAs or graded InGaAs/GaAs was observed from XRD measurements. While the PL peak position of 400 nm thick InAs layer is linearly shifted toward higher energy with increase in excitation intensity ranging from 10 to 140 mW, those of 4 nm InAs epilayer on InGaAs and 1500 nm InAs layer on GaAs is gradually blue-shifted and then, saturated above a power of 75 mW. These results suggest that adopting a graded InGaAs layer between InAs and GaAs can efficiently reduce the strain due to lattice mismatch in the structure of InAs/GaAs.

Role of grain boundaries in the epitaxial realignment of undoped and As-doped polycrystalline silicon films

1993 ◽  
Vol 8 (10) ◽  
pp. 2608-2612 ◽  
Author(s):  
C. Spinella ◽  
F. Benyaïch ◽  
A. Cacciato ◽  
E. Rimini ◽  
G. Fallico ◽  
...  
Keyword(s):  
Heat Treatment ◽  
Grain Structure ◽  
Native Oxide ◽  
Thermally Induced ◽  
Si Substrates ◽  
As Doping ◽  
Fine Grain ◽  
Si Films ◽  
Polycrystalline Silicon Films ◽  
Reduced Density

The early stages of the thermally induced epitaxial realignment of undoped and As-doped polycrystalline Si films deposited onto crystalline Si substrates were monitored by transmission electron microscopy. Under the effect of the heat treatment, the native oxide film at the poly-Si/c-Si interface begins to agglomerate into spherical beads. The grain boundary terminations at the interface are the preferred sites for the triggering of the realignment transformation which starts by the formation of epitaxial protuberances at these sites. This feature, in conjunction with the microstructure of the films during the first instants of the heat treatment, explains the occurrence of two different realignment modes. In undoped films the epitaxial protuberances, due to the fine grain structure, are closely distributed and grow together forming a rough interface moving toward the film's surface. For As-doped films, the larger grain size leaves a reduced density of realignment sites. Due to As doping some of these sites grow fast and form epitaxial columns that further grow laterally at the expense of the surrounding polycrystalline grains.

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