InGaAs/InP Multiquantum well Structures Grown by Trichloride Vapor Phase Epitaxy

1989 ◽  
Vol 145 ◽  
Author(s):  
K. W. Wang ◽  
V. D. Mattera ◽  
K. Tai ◽  
S. N. G. Chu ◽  
D. D. Roccasecca ◽  
...  
Keyword(s):  
High Speed ◽  
High Performance ◽  
Stark Effect ◽  
Optical Modulators ◽  
Double Crystal ◽  
Cross Sectional ◽  
High Modulation ◽  
Transmission Electron ◽  
Device Applications ◽  
Multiquantum Well

AbstractLong wavelength (l.3pm<X<l.551un) InGaAs/InP multiquantum well (MQW) PIN structures in which the quantum confined Stark effect can be observed, are of particular interest because of their potential for high modulation contrast ratios and high speed operation. The chemistry of trichloride VPE lends itself to the growth of high purity InGaAsP heterostructures which are essential for the realization of high performance optical modulators and switches. In this study, we investigate the application of multi-frit trichloride VPE for the highly uniform epitaxial growth of InGaAs/InP MQW structures on two-inch InP substrates for advanced photonic device applications. The growth of MQW structures with various well thicknesses was studied as was the effect of substrate orientation. The structures have been characterized by infrared absorption and photoluminescence spectroscopy, cross-sectional transmission electron microscopy and double crystal x-ray diffraction.

scholarly journals Heterogeneously-Integrated Optical Phase Shifters for Next-Generation Modulators and Switches on a Silicon Photonics Platform: A Review

Micromachines ◽  
2021 ◽  
Vol 12 (6) ◽  
pp. 625
Author(s):  
Younghyun Kim ◽  
Jae-Hoon Han ◽  
Daehwan Ahn ◽  
Sanghyeon Kim
Keyword(s):  
Silicon Photonics ◽  
High Speed ◽  
High Performance ◽  
Phase Shifter ◽  
Phase Shifters ◽  
Next Generation ◽  
Optical Modulators ◽  
Optical Phase ◽  
High Modulation ◽  
Integrated Optical

The realization of a silicon optical phase shifter marked a cornerstone for the development of silicon photonics, and it is expected that optical interconnects based on the technology relax the explosive datacom growth in data centers. High-performance silicon optical modulators and switches, integrated into a chip, play a very important role in optical transceivers, encoding electrical signals onto the light at high speed and routing the optical signals, respectively. The development of the devices is continuously required to meet the ever-increasing data traffic at higher performance and lower cost. Therefore, heterogeneous integration is one of the highly promising approaches, expected to enable high modulation efficiency, low loss, low power consumption, small device footprint, etc. Therefore, we review heterogeneously integrated optical modulators and switches for the next-generation silicon photonic platform.

Recombination of Localized Excitons in InGaN Single- and Multiquantum-Well Structures

1996 ◽  
Vol 449 ◽  
Author(s):  
S. Chichibu ◽  
T. Azuhata ◽  
T. Sota ◽  
S. Nakamura
Keyword(s):  
Quantum Well ◽  
Stark Effect ◽  
Molar Fraction ◽  
Green Light ◽  
Localized States ◽  
Single Quantum Well ◽  
Light Emitting ◽  
Transmission Electron ◽  
Localized Excitons ◽  
Multiquantum Well

ABSTRACTSpontaneous emission mechanisms of InGaN single quantum well (SQW) blue and green light emitting diodes (LEDs) and multiquantum well (MQW) laser diode (LD) structures were investigated. Their static electroluminescence (EL) peak was assigned to the recombination of excitons localized at certain potential minima in the quantum well (QW). The transmission electron micrographs (TEM) indicated fluctuation of In molar fraction in the QWs. The blueshift of the EL peak caused by the increase of the driving current was explained by combined effects of the quantum-confinement Stark effect and band filling of the localized states by excitons.

Analysis of epitaxial CoSi2/Si and Si/CoSi2/Si heterostructures

1986 ◽  
Vol 44 ◽  
pp. 730-731
Author(s):  
N. Lewis ◽  
E. L. Hall ◽  
B. D. Hunt ◽  
L. J. Schowalter
Keyword(s):  
Integrated Circuits ◽  
Ohmic Contacts ◽  
Fluorite Structure ◽  
Metal Silicide ◽  
Cross Sectional ◽  
Metal Base ◽  
Substrate Side ◽  
Transmission Electron ◽  
Device Applications

The formation of thin epitaxial metal silicide layers on Si and Si/metal silicide/Si heterostructures has received considerable attention recently for applications as ohmic contacts, permeable and metal base transistors and 3-D integrated circuits. Cobalt disilioide (CoSi2) is promising for these applications because its cubic fluorite structure is similar to that of Si. In addition, the lattice parameters of CoSi2 and Si are reasonably close (-1.2% mismatch at room temperature) making this system attractive for epitaxial growth. The quality of the epitaxial layers is particularly important for device applications. In this paper the microstructures of several CoSi2/Si and Si/CoSi2/Si specimens were investigated using transmission electron microscopy. Planar and cross-sectional samples were prepared. The planar specimens were first mechanically ground from the Si substrate side and then ion-milled in argon.

Microstructure and Size Distribution of Compound Semiconductor Nanocrystals Synthesized by Ion Implantation

1998 ◽  
Vol 536 ◽  
Author(s):  
A. Meldrum ◽  
S. P. Withrow ◽  
R. A. Zuhr ◽  
C. W. White ◽  
L. A. Boatnerl ◽  
...  
Keyword(s):  
Ion Implantation ◽  
Semiconductor Nanocrystals ◽  
Compound Semiconductor ◽  
Fused Silica ◽  
Silica Matrix ◽  
Cross Sectional ◽  
Transmission Electron ◽  
Host Materials ◽  
Device Applications ◽  
Versatile Technique

AbstractIon implantation is a versatile technique by which compound semiconductor nanocrystals may be synthesized in a wide variety of host materials. The component elements that form the compound of interest are implanted sequentially into the host, and nanocrystalline precipitates then form during thermal annealing. Using this technique, we have synthesized compound semiconductor nanocrystal precipitates of ZnS, CdS, PbS, and CdSe in a fused silica matrix. The resulting microstructures and size distributions were investigated by cross-sectional transmission electron microscopy. Several unusual microstructures were observed, including a band of relatively large nanocrystals at the end of the implant profile for ZnS and CdSe, polycrystalline agglomerates of a new phase such as γ-Zn 2SiO4, and the formation of central voids inside CdS nanocrystals. While each of these microstructures is of fundamental interest, such structures are generally not desirable for potential device applications for which a uniform, monodispersed array of nanocrystals is required. Methods were investigated by which these unusual microstructures could be eliminated.

Microstructural And Microchemical Analysis of Chalcopyrite Cu(In,Ga)Se2 Films

2003 ◽  
Vol 763 ◽  
Author(s):  
Chun-Ming Li ◽  
Chang-Hui Lei ◽  
Ian M. Robertson ◽  
Angus Rockett
Keyword(s):  
Grain Boundaries ◽  
High Performance ◽  
Structural Defects ◽  
Ion Milling ◽  
Mechanical Grinding ◽  
Cross Sectional ◽  
Plan View ◽  
Microchemical Analysis ◽  
Transmission Electron ◽  
Means Of Transmission

AbstractThe microstructure and microchemistry of Cu(In, Ga)Se2 (CIGS) films have been analyzed by means of transmission electron microscopy (TEM). Specimens were obtained from a number of groups producing high-performance solar cells from these materials. Both plan-view and cross-sectional TEM samples were prepared by mechanical grinding and ion milling. Twins can be found easily within the films while dislocations are present only in a few grains and with low density. No extended structural defects such as stacking faults were discovered. X-ray energy dispersive spectroscopy was used to study the chemical composition of grains and grain boundaries. Experimental results showed no difference between the composition in the grain interiors and the grain boundary. In addition, there is no obvious enhancement of oxygen and sodium at grain boundaries. Structural depth dependences were also not found.

Epitaxial Thin Films And Heterostrcutures of Various Isotropic Metallic Oxides for Device Applications

1994 ◽  
Vol 341 ◽  
Author(s):  
C. B. Eom ◽  
Julia M. Phillips ◽  
R. J. Cava
Keyword(s):  
Thin Films ◽  
Cuprate Superconductors ◽  
Superconducting Devices ◽  
Epitaxial Thin Films ◽  
Metallic Oxide ◽  
Cross Sectional ◽  
Lattice Match ◽  
Metallic Oxides ◽  
Transmission Electron ◽  
Device Applications

AbstractWe have grown epitaxial thin films of various isotropic metallic oxides such as Sr1-xCaxRuO3 and La8-xSrxCu8O2Oin situ by 90° off-axis sputtering. These metallic oxides are pseudo-cubic perovskites with essentially isotropic properties, which could be ideal normal metals for SNS junctions in superconducting devices and for electrodes in ferroelectric devices. We have fabricated epitaxial ferroelectric heterostructures [SrRuO3/Pb(Zr0. 52 Ti0.4 8) O3 /SrRuO3] employing isotropic metallic oxide (SrRuO3) electrodes on substrates of (100) SrTiO3 and (100) Si with an yttria stabilized zirconia buffer layer. They exhibit superior fatigue characteristics over those made with metal electrodes, showing little degradation over 10 cycles, with a large remnant polarization (27 μC/cm2 ). We have also grown epitaxial superconducting heterostructures (YBa2Cu3O7 / La8-xSrxCu8O2O / YBa2Cu3O7 ) with a copper-oxide-based isotropic metallic oxide (La8-xSrxCu8O20) normal metal barrier. X-ray diffraction and cross-sectional transmission electron microscopy reveal these heterostructures to have high crystalline quality and clean interfaces. This material will facilitate fabrication of ideal SNS Josephson junctions with low boundary resistance due to its excellent chemical compatibility and lattice match with cuprate superconductors and will be useful for determining the source of interface resistance in such heterostructures.

scholarly journals Fluid Flow Characteristics of a Co-Flow Fluidic Slot Jet Thrust Augmentation Propulsion System

2020 ◽  
Author(s):  
Brian Garrett ◽  
Kareem Ahmed
Keyword(s):  
Fluid Flow ◽  
Turbulent Mixing ◽  
High Speed ◽  
High Performance ◽  
Flow Characteristics ◽  
Propulsion System ◽  
Secondary Flows ◽  
High Momentum ◽  
Cross Sectional ◽  
Bulk Fluid

Abstract The UAV industry is booming with investments in research and development on improving UAV systems. Current UAV machines are developed according to the quadcopter design which consists of a rotary propulsion system providing lift needed for flight. This design has some flaws; namely safety concerns and noise/vibration production both of which come stem from the rotary propulsion system. As such, a novel propulsion system using slip stream air passed through high performance slot jets is proposed and an analysis of the fluid characteristics is presented in this report. The test section for the experiment is developed using 3D printed ABS plastic airfoils modified with internal cavities where pressurized air is introduced and then expelled through slot jets on the pressure side of the airfoils. Entrainment processes develop in the system through high momentum fluid introduction into a sedentary secondary fluid. Entrainment is governed by pressure gradients and turbulent mixing and so turbulent quantities that measure these processes are extracted and analyzed according to the independent variable’s effects on these quantities. Pitot probe testing extracted one dimensional fluid information and PIV analysis is used to characterize the two-dimensional flow aspects. High slot jet velocities are seen to develop flows dominated by convection pushing momentum mixing downstream reducing the mixing in the system while low slot jet speeds exhibit higher mass fluxes and thrust development. Confinement spacing is seen to cause a decrease in flow velocity and thrust as the spacing is decreased for high speed runs. The most constricted cross sectional runs showed high momentum mixing and developed combined self-similar flow through higher boundary layer interactions and pressures, but this also hurts thrust development by minimizing secondary flows. The Angle of Attack of the assembly proved to be the most important variable. Outward angling showed the influence of coanda effects but also demonstrated the highest bulk fluid flow with turbulence driven momentum mixing. Inward angling created combined fluid flow downstream with high momentum mixing upstream driven by pressure. Minimal mixing is seen when the airfoils are not angled, and high recirculation zones occur along the boundaries. The optimal setup is seen when the airfoils are angled outwards where the highest thrust and bulk fluid movement is developed driven by the turbulent mixing induced by the increasing cross sectional area of the system.

Lateral Epitaxial Overgrowth of InAs on (100) GaAs Substrates

2002 ◽  
Vol 744 ◽  
Author(s):  
Ganesan Suryanarayanan ◽  
Anish A. Khandekar ◽  
Brian E. Hawkins ◽  
Thomas F. Kuech ◽  
Susan E. Babcock
Keyword(s):  
Electron Microscopy ◽  
Extended Defects ◽  
Double Crystal ◽  
Cross Sectional ◽  
Lateral Epitaxial Overgrowth ◽  
X Ray ◽  
Gaas Substrates ◽  
Transmission Electron ◽  
Order Of Magnitude ◽  
Inas Thin Films

ABSTRACTThe microstructure of epitaxial InAs thin films grown by MOCVD on mask-patterned “LEO” (lateral epitaxial overgrowth) GaAs and on unpatterned GaAs substrates was studied using double-crystal x-ray diffraction, scanning electron microscopy and cross-sectional transmission electron microscopy. This paper describes the improvement in crystal quality (factor of 20 reduction in x-ray rocking curve width), the order of magnitude reduction in dislocation density, and the rearrangement of the remaining extended defects that were observed in the LEO material when compared to the film grown on the unpatterned wafer.

High-speed and low-driving-voltage InGaAs/InAlAs multiquantum well optical modulators

1991 ◽  
Vol 27 (23) ◽  
pp. 2162 ◽  
Author(s):  
I. Kotaka ◽  
K. Wakita ◽  
K. Kawano ◽  
M. Asai ◽  
M. Naganuma
Keyword(s):  
High Speed ◽  
Driving Voltage ◽  
Optical Modulators ◽  
Multiquantum Well

scholarly journals Synthesis and Characterization of Graphene Oxide Derivatives via Functionalization Reaction with Hexamethylene Diisocyanate

Nanomaterials ◽  
2018 ◽  
Vol 8 (11) ◽  
pp. 870 ◽  
Author(s):  
Jose Luceño-Sánchez ◽  
Georgiana Maties ◽  
Camino Gonzalez-Arellano ◽  
Ana Diez-Pascual
Keyword(s):  
Graphene Oxide ◽  
High Performance ◽  
Hexamethylene Diisocyanate ◽  
Covalent Attachment ◽  
Aprotic Solvents ◽  
Transmission Electron ◽  
Device Applications ◽  
Oxygen Groups ◽  
Functionalization Reaction

Graphene oxide (GO), the oxidized form of graphene, shows unique properties including high mechanical strength, optical transparency, amphiphilicity and surface functionalization capability that make it attractive in fields ranging from medicine to optoelectronic devices and solar cells. However, its insolubility in non-polar and polar aprotic solvents hinders some applications. To solve this issue, novel functionalization strategies are pursued. In this regard, this study deals with the preparation and characterization of hexamethylene diisocyanate (HDI)-functionalized GO. Different reaction conditions were tested to optimize the functionalization degree (FD), and detailed characterizations were conducted via elemental analysis, Fourier-transformed infrared (FT-IR) and Raman spectroscopies to confirm the success of the functionalization reaction. The morphology of HDI-GO was investigated by transmission electron microscopy (TEM), which revealed an increase in the flake thickness with increasing FD. The HDI-GO showed a more hydrophobic nature than pristine GO and could be suspended in polar aprotic solvents such as N,N-dimethylformamide (DMF), N-methylpyrrolidone (NMP) and dimethyl sulfoxide (DMSO) as well as in low polar/non-polar solvents like tetrahydrofuran (THF), chloroform and toluene; further, the dispersibility improved upon increasing FD. Thermogravimetric analysis (TGA) confirmed that the covalent attachment of HDI greatly improves the thermal stability of GO, ascribed to the crosslinking between adjacent sheets, which is interesting for long-term electronics and electrothermal device applications. The HDI-GO samples can further react with organic molecules or polymers via the remaining oxygen groups, hence are ideal candidates as nanofillers for high-performance GO-based polymer nanocomposites.

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