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.

Heteroepitaxy of Ge on Cube-Textured Ni(001) Foils Through CaF2 Buffer Layer

MRS Advances ◽  
2016 ◽  
Vol 1 (43) ◽  
pp. 2947-2952
Author(s):  
L. Chen ◽  
Z.-H. Lu ◽  
T.-M. Lu ◽  
I. Bhat ◽  
S.B. Zhang ◽  
...  
Keyword(s):  
Buffer Layer ◽  
High Efficiency ◽  
Electron Backscatter Diffraction ◽  
Low Cost ◽  
High Quality ◽  
Tem Analysis ◽  
Transmission Electron ◽  
Electron Backscatter ◽  
Image Position ◽  
Backscatter Diffraction

ABSTRACTEpitaxial Ge films are useful as a substrate for high-efficiency solar cell applications. It is possible to grow epitaxial Ge films on low cost, cube textured Ni(001) sheets using CaF2(001) as a buffer layer. Transmission electron microscopy (TEM) analysis indicates that the CaF2(001) lattice has a 45o in-plane rotation relative to the Ni(001) lattice. The in-plane epitaxy relationships are CaF2[110]//Ni[100] and CaF2[$\bar 1$10]//Ni[010]. Energy dispersive spectroscopy (EDS) shows a sharp interface between Ge/CaF2 as well as between CaF2/Ni. Electron backscatter diffraction (EBSD) shows that the Ge(001) film has a large grain size (∼50 μm) with small angle grain boundaries (< 8o). The epitaxial Ge thin film has the potential to be used as a substrate to grow high quality III-V and II-VI semiconductors for optoelectronic applications.

scholarly journals Hybrid Organic-Inorganic Perovskites Open a New Era for Low-Cost, High Efficiency Solar Cells

2015 ◽  
Vol 2015 ◽  
pp. 1-10 ◽  
Author(s):  
Guiming Peng ◽  
Xueqing Xu ◽  
Gang Xu
Keyword(s):  
Solar Cells ◽  
Solar Energy ◽  
High Efficiency ◽  
Low Cost ◽  
Power Conversion ◽  
Perovskite Solar Cells ◽  
Device Structure ◽  
New Era ◽  
High Efficiency Solar Cells ◽  
Conversion Efficiencies

The ramping solar energy to electricity conversion efficiencies of hybrid organic-inorganic perovskite solar cells during the last five years have opened new doors to low-cost solar energy. The record power conversion efficiency has climbed to 19.3% in August 2014 and then jumped to 20.1% in November. In this review, the main achievements for perovskite solar cells categorized from a viewpoint of device structure are overviewed. The challenges and prospects for future development of this field are also briefly presented.

Microstructural and Electrical Characterization of Misfit Dislocations at the InAs/GaP Heterointerface

1997 ◽  
Vol 500 ◽  
Author(s):  
V. Gopal ◽  
T. P. Chin ◽  
A. L. Vasiliev ◽  
J. M. Woodall ◽  
E. P. Kvam
Keyword(s):  
Misfit Dislocation ◽  
Lattice Mismatch ◽  
Electrical Characterization ◽  
Growth Conditions ◽  
Misfit Dislocations ◽  
Ir Detectors ◽  
Mbe Growth ◽  
Transmission Electron ◽  
Hall Effect Measurements ◽  
Edge Dislocations

ABSTRACTInAs is a narrow band gap semiconductor with potential for such applications as IR detectors, low temperature transistors, etc‥ However, the lack of suitable substrates has hampered progress in the development of InAs based devices. In the present study, InAs was grown by Molecular Beam Epitaxy on (001) GaP substrates. Though this system has a high lattice mismatch, (∼11%), certain MBE growth conditions result in 80% relaxed InAs layers on GaP with the mismatch accommodated predominantly by 90° pure edge dislocations. Misfit dislocation microstructures were studied using Transmission Electron Microscopy. Electrical characterization using lateral conductance and Hall effect measurements were also performed. Preliminary results indicate the possibility of misfit dislocation related conductivity. The possible correlation between interface structure and electrical properties is discussed.

Novel synthesis of AlN nanowires with controlled diameters

2001 ◽  
Vol 16 (11) ◽  
pp. 3133-3138 ◽  
Author(s):  
Jun Liu ◽  
X. Zhang ◽  
Yingjiu Zhang ◽  
Rongrui He ◽  
Jing Zhu
Keyword(s):  
Electron Microscopy ◽  
Carbon Nanotubes ◽  
High Efficiency ◽  
Low Cost ◽  
X Ray Diffraction ◽  
Synthesis Mechanism ◽  
X Ray ◽  
Novel Synthesis ◽  
Transmission Electron ◽  
New Synthesis

A relatively low-cost, high-efficiency method is reported to synthesize AlN nanowires, using carbon nanotubes as templates. The AlN nanowires were fabricated at 1100 °C, for 60 min. The diameters of the product could be roughly controlled by the sizes of carbon nanotubes selected as starting materials. The AlN nanowires obtained were among the thinnest ever known. X-ray diffraction, selected-area diffraction, energy dispersive spectroscopy, and high-resolution transmission electron microscopy, etc. were employed to characterize the products, which were found to be single crystals with some defects. The axes of the nanowires are normal to {1010} crystal planes. A new synthesis mechanism is proposed.

3C-SiC Growth on (001) Si Substrates by Using a Multilayer Buffer

2013 ◽  
Vol 740-742 ◽  
pp. 263-266 ◽  
Author(s):  
Andrea Canino ◽  
Andrea Severino ◽  
Nicolò Piluso ◽  
Francesco La Via ◽  
Stefania Privitera ◽  
...  
Keyword(s):  
Driving Force ◽  
Lattice Mismatch ◽  
Low Cost ◽  
Structural Features ◽  
Silicon Substrates ◽  
Fundamental Issue ◽  
Si Substrates ◽  
N Doping ◽  
Silicon Based ◽  
Buffer Structure

3C-SiC shows encouraging physical properties for the development of low cost high power compatible silicon based technology. The fundamental capability of grown 3C-SiC on silicon substrates leads to the possibility of a full integration of Si based process technologies. This is the driving force for the efforts for development a high quality heteroepitaxial film. The fundamental issue is the reduction of defects and stress due to the lattice mismatch between the 3C-SiC epilayer and the Silicon substrate. In this paper we show a way to reduce macroscopic structural features and to enhance the material quality and the surface quality by simply using a process based on a multilayer (ML) buffer structure with n++ and n doping alternation. This process leads to an evident improvement of both surface roughness, morphology and crystal quality.

scholarly journals Technology for obtaining modified oil sorbents

2021 ◽  
Vol 82 (4) ◽  
pp. 247-253
Author(s):  
R. Mejri ◽  
Y. S. Peregudov ◽  
E. M. Gorbunova
Keyword(s):  
Magnetic Properties ◽  
High Efficiency ◽  
Low Cost ◽  
Oil Products ◽  
Solid Surfaces ◽  
Environmental Friendliness ◽  
Transmission Electron ◽  
Oil Sorbent ◽  
High Degree ◽  
Oil And Oil Products

Expediency of using natural glauconite material as a basis for the production of an environmentally friendly sorbent with hydrophobic and magnetic properties for liquidating oil and oil products spills mechanically and using a magnetic field has been substantiated and experimentally proved. Fractional, elemental and oxide compositions of the original mineral have been studied. The structure of glauconite fraction 0.045-0.1 mm has been investigated by transmission electron microscopy. It was found that the surface of the sample particles is heterogeneous with a large number of pores and cracks. Based on the experimental data, the optimal conditions for the production and use of powder and granular sorbents based on glauconite with specified properties were determined, at which a high degree of recovery (more than 90%) of oil with water and hard surfaces. The optimum temperature for obtaining a magnetic oil sorbent is 400 °C. The doses of stearic acid and iron (III) oxide were established at 5 wt. %, which provide hydrophobicity and magnetic properties to the synthesized sorbent. A high degree of oil (97%) and oil (98%) recovery when using a sorbent is achieved at a ratio of 1: 10 to sorbate. To eliminate oil and oil product spills, it is proposed to use granular ferromagnetic sorbents obtained by introducing carboxymethyl cellulose into the modified glauconite composition. oil and oil products granular sorbent increases in comparison with the original mineral by 1.2–2.2 times. Technological schemes for obtaining ferromagnetic hydrophobic and granular sorbents based on glauconite for collecting oil and oil products from water and solid surfaces have been developed. The synthesized sorbents are characterized by high efficiency, low cost, and environmental friendliness.

TEM study of buried yttrium silicide formed by ion implantation

1990 ◽  
Vol 48 (4) ◽  
pp. 570-571
Author(s):  
T.L. Alford ◽  
N.D. Theodore ◽  
J.C. Barbour ◽  
C.B. Carter ◽  
J.W. Mayer
Keyword(s):  
Ion Implantation ◽  
Large Scale ◽  
Schottky Barrier Height ◽  
Lattice Mismatch ◽  
Good Thermal Stability ◽  
Si Substrates ◽  
Transmission Electron ◽  
Metal Silicides ◽  
Vacuum Anneal ◽  
Buried Layers

Metal silicides are now used extensively in very-large-scale-integrated (VLSI) electronics due to their low resistivity, good thermal stability, and ability to form on Si. Of these silicides, yttrium silicide, YSi2-x has essentially 0% lattice mismatch with (111)Si, a low Schottky barrier height on n-type Si, and a unit cell based on the AlB2-type structure, but with 15-20% vacancies on the Si sublattice. Recent investigations of high-temperature ion implantation of yttrium ions into Si have emphasized the formation of buried-silicide layers. This study is focussed on the microstructure and defects in the vicinity of buried YSi2-x layers formed by Y-ion implantation into Si.Yttrium-silicide buried layers were formed by implanting 330 or 660 keV Y ions into (11l)Si substrates held at 450°C followed by a 1000°C, 1-hour vacuum anneal. The implant fluences varied from 1 to 3.6×l017 Y/cm2. Cross-section transmission electron microscopy (XTEM) analysis was carried out using a JEOL 4000EX electron microscope operating at 400 kV.

Rotated Epitaxy of 3C-SiC(111) on Si(110) Substrate Using Monomethylsilane-Based Gas-Source Molecular-Beam Epitaxy

2013 ◽  
Vol 740-742 ◽  
pp. 339-343 ◽  
Author(s):  
Shota Sambonsuge ◽  
Eiji Saito ◽  
Myung Ho Jung ◽  
Hirokazu Fukidome ◽  
Sergey Filimonov ◽  
...  
Keyword(s):  
Molecular Beam Epitaxy ◽  
Molecular Beam ◽  
Lattice Mismatch ◽  
Growth Conditions ◽  
Si Substrate ◽  
Si Substrates ◽  
High Interest ◽  
Gas Source ◽  
Gas Pressures

3C-SiC is the only polytype that grows heteroepitaxially on Si substrates and, therefore, it is of high interest for various potentail applications. However, the large (~20 %) lattice mismatch of SiC with the Si substrate causes a serious problem. In this respect, rotated epitaxy of 3C-SiC(111) on the Si(110) substrate is highly promising because it allows reduction of the lattice mismatch down to a few percent. We have systematically searched the growth conditions for the onset of this rotated epitaxy, and have found that the rotaed epitaxy occurrs at higher growth temperatures and at lower source-gas pressures. This result indicates that the rotated epitaxy occurs under growth conditions that are close to the equilibrium and is thefore thermodynamically, rather than kinetically, driven.

Dissociation of Misfit Dislocations in GeSi/{111}Si Interfaces

1993 ◽  
Vol 319 ◽  
Author(s):  
Frank Ernst
Keyword(s):  
Lattice Mismatch ◽  
Stacking Faults ◽  
Chemical Vapor ◽  
Interfacial Area ◽  
Dark Field ◽  
Dislocation Network ◽  
Misfit Dislocations ◽  
Si Substrates ◽  
Weak Beam ◽  
Transmission Electron

AbstractThe accommodation of lattice mismatch is studied in Ge0.15Si0.85 layers grown epitaxially on {111}-oriented Si substrates by chemical vapor deposition (CVD) at 1100°C. Weak beam dark field microscopy reveals a regular misfit dislocation network, which resembles the honeycomb network of edge-type dislocations anticipated by the O-lattice theory. In contrast to the latter, however, the real network exhibits extended nodes where the misfit dislocations dissociate into misfit partial dislocations. Between the partials, high resolution transmission electron microscopy (HRTEM) reveals intrinsic and extrinsic stacking faults. Owing to the presence of these stacking faults, three different atomistic structures of the GeSi/Si interface coexist and compete for the interfacial area according to their energy. The observed configuration is shown to minimize the total energy of the interface.

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