Surface Reconstruction and Morphology of Hydrogen Sulfide Treated GaAs (001) Substrate

1996 ◽  
Vol 448 ◽  
Author(s):  
Jun Suda ◽  
Yoichi Kawakami ◽  
Shizuo Fujita ◽  
Shigeo Fujita
Keyword(s):  
Hydrogen Sulfide ◽  
Surface Reconstruction ◽  
Substrate Surface ◽  
High Vacuum ◽  
High Energy ◽  
Gaas Surface ◽  
Ex Situ ◽  
Force Microscopy ◽  
Atomic Force ◽  
Strained Quantum Well

AbstractWe report several new results in hydrogen sulfide (H2S) treatment of a GaAs (001) substrate. Surface reconstruction and morphology were investigated by in situ reflection high energy electron diffraction (RHEED) and ex situ atomic force microscopy (AFM) in terms of the annealing temperature and the H2S irradiation sequence. A (4 × 3) GaAs surface was obtained by annealing the substrate under H2S irradiation (4 × 10-7 Torr). The surface was atomically flat, i.e., large terraces with monolayer steps were clearly observed. A (2 × 6) S-terminated GaAs surface was obtained by irradiation H2S at 300°C on a Ga-terminated surface, which was formed by annealing at 580°C in high vacuum. The molecular beam epitaxy (MBE) growth of ZnSSe-based semiconductors on the (4 × 3) surface results in high quality structures such as a novel ZnSSe/ZnMgSSe tensile-strained quantum well (QW).

Properties of Metal / Polyphenylquinoxaline Interfaces

1994 ◽  
Vol 337 ◽  
Author(s):  
L. Bellard ◽  
J.M. Themlin ◽  
F. Palmino ◽  
A. Cros
Keyword(s):  
Metal Layer ◽  
High Vacuum ◽  
Polymer Surface ◽  
Pure Metal ◽  
Ultra High Vacuum ◽  
Ex Situ ◽  
Layer By Layer ◽  
Force Microscopy ◽  
Atomic Force

ABSTRACTWe have investigated the microscopic properties of copper and chromium layers deposited on polyphenylquinoxaline (PPQ). PPQ is a thermostable polymer used for multichip module applications. The metal is deposited under ultra-high vacuum conditions and analysed in-situ by X-ray photoemission (XPS) and atomic force microscopy (ex situ). Copper does not react significantly with the PPQ and tends to diffuse into the polymer matrix upon annealing. On the contrary, chromium strongly reacts with the polymer surface at room temperature. With increasing metal coverage, chromium grows in a layer-by-layer mode and the reacted interface is progressively burried under the pure metal layer.

Well-Ordered Self-Assembly Growth of Strain-Modulated SrTiO3 Thin Films: Templates for Complex Oxide Quantum Wires

2005 ◽  
Vol 475-479 ◽  
pp. 4255-4260 ◽  
Author(s):  
Yan Rong Li ◽  
Jin Long Li ◽  
Ying Zhang ◽  
Xin Wu Deng ◽  
Fan Yang ◽  
...  
Keyword(s):  
Compressive Stress ◽  
Self Assembly ◽  
Quantum Wires ◽  
Complex Oxide ◽  
High Energy ◽  
The Self ◽  
Ex Situ ◽  
Force Microscopy ◽  
Atomic Force ◽  
Self Assembled

Well-ordered self-assembled SrTiO3 thin film, as a template for complex oxide quantum wires, was fabricated on LaAlO3 (100) single crystal substrates with laser molecular beam epitaxy. The self-assembled growth was in-situ monitored by reflective high energy electron diffraction. The morphology evolutions of the films as a function of thickness were studied by ex-situ atomic force microscopy. As the thickness of the films increased from 3.875nm to 46.5nm gradually, the compressive stress-induced SrTiO3 films exhibited a periodic well-ordered ripple structure, which formed a unique nanoassembled template for the fabrication of quantum wires. Small angle X-ray scattering technique was employed to investigate the structure. Symmetric satellite peaks were discovered, indicating the well-ordered superstructure. In contrast, the similar superstructure was not observed during the growth of the tensile stress-induced LaAlO3 films on SrTiO3 substrates. The Compressive stress was considered as the main reason of the self-assembled growth, and systematical elucidation about strain mechanism was discussed. These results might provide an efficient method for the controllable formation of well-aligned template of quantum wire for complex oxide with desirable structure via proper modulation of strains.

MBE Growth of IV-VI Nanowires on a Self-organized Template

2010 ◽  
Vol 1258 ◽  
Author(s):  
Lee Andrew Elizondo ◽  
Patrick McCann ◽  
Joel Keay ◽  
Matthew Johnson
Keyword(s):  
Quantum Wires ◽  
High Energy ◽  
Ex Situ ◽  
Mbe Growth ◽  
One Dimensional ◽  
Force Microscopy ◽  
Self Organized ◽  
Atomic Force ◽  
Low Dimensional

AbstractWe present the experimental results for the first known molecular beam epitaxy (MBE) growth of quasi-one-dimensional PbSe wires on technologically relevant silicon.In this work, we describe the growth and characterization of low-dimensional IV-VI semiconductors as they evolve from one-dimensional dot/dot-chains to one-dimensional structures on a self-organized template epitaxially grown on Si(110). In situ and ex situ characterization were performed at various stages throughout growth by reflection high energy electron diffraction, scanning electron microscopy, and non-contact atomic force microscopy. Initial growths resulted in some preferential alignment of the PbSe dot-chains parallel to the self-organized template in the [-110] direction. By reducing the substrate temperature and increasing the supplemental Se flux, the morphology of dot-chains extend into lengthened one-dimensional structures. This is an important milestone in the fabrication of PbSe quantum wires on technologically relevant silicon.

STRUCTURAL AND MAGNETIC PROPERTIES OF EPITAXIAL Ni80Fe20 THIN FILMS ON Cu/Si

1995 ◽  
Vol 02 (04) ◽  
pp. 427-437 ◽  
Author(s):  
I. HASHIM ◽  
H.S. JOO ◽  
H.A. ATWATER
Keyword(s):  
Magnetic Properties ◽  
Domain Walls ◽  
High Energy ◽  
Ex Situ ◽  
Misfit Dislocations ◽  
Force Microscopy ◽  
Atomic Force ◽  
Transmission Electron ◽  
Crystal Films

Single-crystal films of permalloy ( Ni 80 Fe 20) were grown on Cu (001) seed layers oriented epitaxially with Si (001). The microstructural properties were measured using in-situ reflection high-energy electron diffraction, and ex-situ transmission electron microscopy, x-ray diffraction, and atomic force microscopy, whereas the magnetic properties were probed using in-situ magneto-optic Kerr effect and ex-situ vibrating sample magnetometry. Anisotropic magnetoresistance and resistivity for some of the samples were also measured. The coercivity for thinner (≤5 nm) Ni 80 Fe 20 was significantly higher (10–20 Oersteds) than polycrystalline films deposited on SiO 2/ Si , and was also higher than films deposited on lattice-matched Cu x Ni 1–x alloys. These magnetic properties were explained using a theoretical model involving interaction of domain walls with defects such as misfit dislocations and coherent islands, due to the mismatch between Ni 80 Fe 20 and Cu .

Thermal Interactions of Ni on Stepped 6H-SiC Surfaces: Implications for Thin Film Microstructure

2006 ◽  
Vol 911 ◽  
Author(s):  
Andrew Woodworth ◽  
Srikanth Raghavan ◽  
Charter D Stinespring
Keyword(s):  
High Temperature ◽  
Ohmic Contacts ◽  
Substrate Surface ◽  
Device Fabrication ◽  
Ex Situ ◽  
Force Microscopy ◽  
Stepped Surfaces ◽  
Atomic Force ◽  
Film Microstructure ◽  
Schottky Junctions

AbstractNi films are important as both Schottky junctions and Ohmic contacts for high temperature SiC devices. Ni/SiC Schottky junctions are observed to become Ohmic upon annealing. This transition has been attributed to changes in film microstructure. The experiments reported here compare the thermal behavior of Ni films deposited on standard 6H-SiC (0001) surfaces with films deposited on periodically stepped surfaces. The former were prepared by wet chemical etching and are typical of those used in device fabrication. The latter were prepared by high temperature hydrogen etching. Ni films ranging from monolayer to nominal device thickness (~50 nm) were annealed on both surfaces. Analysis of these surfaces by in-situ Auger electron spectroscopy (AES) and ex-situ atomic force microscopy (AFM) provided elemental, chemical and morphological information. The results show that the morphology and microstructure of annealed films are dependent on initial film thickness and substrate surface conditions.

Dynamics of InAs Quantum Dots Formation on AlAs and GaAs

2000 ◽  
Vol 648 ◽  
Author(s):  
M. Yakimov ◽  
V. Tokranov ◽  
S. Oktyabrsky
Keyword(s):  
Quantum Dots ◽  
Self Assembly ◽  
Single Layer ◽  
High Energy ◽  
Ex Situ ◽  
Inas Quantum Dots ◽  
Force Microscopy ◽  
Atomic Force ◽  
Kinetics Of

AbstractWe have studied the formation of InAs quantum dots (QDs) grown by molecular beam epitaxy on top of GaAs and 2 ML-thick AlAs layers in the temperature range from 350 to 500°C. In-situ reflection high energy electron diffraction (RHEED) patterns were recorded in real time during the growth and analyzed to characterize the 2D-to-3D transition on the surface, including QD formation, and ripening process. The kinetics of QD formation was studied using the InAs growth rates ranging from 0.01 to 1 ML/s and different ratios of As2/In fluxes. RHEED patterns and ex-situ atomic force microscopy images were analyzed to reveal the development of sizes and shapes of the single-layer and stacked QD ensembles. The critical InAs coverage for QD formation was shown to be consistently higher for dots grown on the AlAs overlayer than for those grown on GaAs surface. Self-assembly of multilayer QD stacks revealed the reduction of the critical thickness for dots formed in the upper layers.

Transmission Electron Microscopy of Epitaxial silicides grown by ultra high vacuum deposition

1989 ◽  
Vol 47 ◽  
pp. 462-463
Author(s):  
D. Loretto ◽  
J. M. Gibson ◽  
S. M. Yalisove
Keyword(s):  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
Electron Diffraction ◽  
High Vacuum ◽  
High Energy ◽  
Energy Electron ◽  
Ultra High Vacuum ◽  
Ex Situ ◽  
Transmission Electron

The silicides CoSi2 and NiSi2 are both metallic with the fee flourite structure and lattice constants which are close to silicon (1.2% and 0.6% smaller at room temperature respectively) Consequently epitaxial cobalt and nickel disilicide can be grown on silicon. If these layers are formed by ultra high vacuum (UHV) deposition (also known as molecular beam epitaxy or MBE) their thickness can be controlled to within a few monolayers. Such ultrathin metal/silicon systems have many potential applications: for example electronic devices based on ballistic transport. They also provide a model system to study the properties of heterointerfaces. In this work we will discuss results obtained using in situ and ex situ transmission electron microscopy (TEM).In situ TEM is suited to the study of MBE growth for several reasons. It offers high spatial resolution and the ability to penetrate many monolayers of material. This is in contrast to the techniques which are usually employed for in situ measurements in MBE, for example low energy electron diffraction (LEED) and reflection high energy electron diffraction (RHEED), which are both sensitive to only a few monolayers at the surface.

In situ X-ray Scattering Study of the Formation of Au Nano Crystals During Thermal Annealing

2007 ◽  
Vol 1027 ◽  
Author(s):  
Do Young Noh ◽  
Ki-Hyun Ryu ◽  
Hyon Chol Kang
Keyword(s):  
Thermal Annealing ◽  
Bragg Reflection ◽  
Ex Situ ◽  
X Ray ◽  
Force Microscopy ◽  
X Ray Scattering ◽  
Atomic Force ◽  
Au Thin Films ◽  
Ray Scattering

AbstractThe transformation of Au thin films grown on sapphire (0001) substrates into nano crystals during thermal annealing was investigated by in situ synchrotron x-ray scattering and ex situ atomic force microscopy (AFM). By monitoring the Au(111) Bragg reflection and the low Q reflectivity and comparing them with ex situ AFM images, we found that polygonal-shape holes were nucleated and grow initially. As the holes grow larger and contact each other, their boundary turns into Au nano crystals. The Au nano crystals have a well-defined (111) flat top surface and facets in the in-plane direction.

Ex Situ and In Situ Thermal Transformations of M-50 Pitch Revealed by Non-contact Atomic Force Microscopy

2021 ◽  
Author(s):  
Pengcheng Chen ◽  
Jordan N. Metz ◽  
Adam S. Gross ◽  
Stuart E. Smith ◽  
Steven P. Rucker ◽  
...  
Keyword(s):  
Atomic Force Microscopy ◽  
Ex Situ ◽  
Thermal Transformations ◽  
Force Microscopy ◽  
Atomic Force

scholarly journals Growth of Ordered Graphene Ribbons by Sublimation Epitaxy

Crystals ◽  
2018 ◽  
Vol 8 (12) ◽  
pp. 449
Author(s):  
Shuxian Cai ◽  
Xingfang Liu ◽  
Xin Zheng ◽  
Zhonghua Liu
Keyword(s):  
Substrate Surface ◽  
Graphene Film ◽  
Graphene Ribbon ◽  
High Quality ◽  
Graphene Layers ◽  
Force Microscopy ◽  
Layer Graphene ◽  
Micro Raman Spectroscopy ◽  
Atomic Force ◽  
Few Layer Graphene

Ordered graphene ribbons were grown on the surface of 4° off-axis 4H-SiC wafers by sublimation epitaxy, and characterized by using scanning electron microscopy (SEM), atomic force microscopy (AFM) and micro-Raman spectroscopy (μ-Raman). SEM showed that there were gray and dark ribbons on the substrate surface, and AFM further revealed that these ordered graphene ribbons had clear stepped morphologies due to surface step-bunching. It was shown by μ-Raman that the numbers of graphene layers of these two types of regions were different. The gray region was composed of mono- or bilayer ordered graphene ribbon, while the dark region was of tri- or few-layer ribbon. Meanwhile, ribbons were all homogeneous and had a width up to 40 μm and a length up to 1000 μm, without micro defects such as grain boundaries, ridges, or mono- and few-layer graphene mixtures. The results of this study are useful for optimized growth of high-quality graphene film on silicon carbide crystal.

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