In Situ Hrem Observations of Crystallization in LPCVD Amorphous Silicon

1990 ◽  
Vol 182 ◽  
Author(s):  
J. Morgiel ◽  
I.W. Wu ◽  
A. Chiang ◽  
R. Sinclair
Keyword(s):  
Amorphous Silicon ◽  
Elevated Temperatures ◽  
Technological Development ◽  
High Resolution Electron Microscopy ◽  
Nucleation And Growth ◽  
Crystal Nucleation ◽  
Dynamic Events ◽  
Fundamental Information ◽  
Resolution Electron

AbstractThis article describes the application of in situ, high-resolution electron microscopy to the study of crystal nucleation and growth in amorphous silicon. It is shown that dynamic events at elevated temperatures (e.g. 600-750°C) can be recorded at the atomic level by such an approach. It is anticipated that fundamental information, important for the technological development of polysilicon thin films, can be generated by work of this type.

An in Situ Hrem Study of Crystal Nucleation in Amorphous Silicon thin Films

1990 ◽  
Vol 202 ◽  
Author(s):  
A. S. Kirtikar ◽  
J. Morgiel ◽  
R. Sinclair ◽  
I-W. Wu ◽  
A. Chiang
Keyword(s):  
Thin Films ◽  
Solid Phase ◽  
High Resolution Electron Microscopy ◽  
Nucleation Theory ◽  
Crystal Nucleation ◽  
Classical Nucleation Theory ◽  
Interface Reactions ◽  
Silicon Thin Films ◽  
Resolution Electron

ABSTRACTIn Situ high resolution electron microscopy has proved to be a valuable tool in investigations involving interface reactions in a number of thin film systems. We have applied this technique to dynamically record nucleation and growth sequences during the amorphous (a-) to crystalline (c-) phase transformation in silicon thin films. Interpretation of the recordings has yielded a wealth of information on the mechanisms and to some extent the kinetics of solid phase crystallization. In our recordings, we have been able to capture the critical nucleus at the a-Si-SiO2 interface. Incorporating this into classical nucleation theory enables us to make an estimate of the a-Si-c-Si interfacial energy.

HREM of electron-irradiated silicas

1993 ◽  
Vol 51 ◽  
pp. 1102-1103 ◽  
Author(s):  
L.C. Qin
Keyword(s):  
Electron Irradiation ◽  
Structural Changes ◽  
High Resolution Electron Microscopy ◽  
Nucleation And Growth ◽  
Sharp Boundary ◽  
Quartz Crystals ◽  
Resolution Electron ◽  
Silica Crystals ◽  
Crystalline Matrix

Silica (SiO2) crystals exist in various polymorphs which have different densities and different crystal structures, such as quartz, tridymite, and cristobalite, though all of these have in common the network structure which is formed by corner-sharing of SiO4 tetranedra. All these structures are sensitive to electron irradiation. Amorphization occurs when they are irradiated by energetic electrons.In the present study three polymorphs of silica crystals, α-quartz, α-tridymite and α-cristobalite crystals2 were used as starting materials. Electron irradiation experiments were carried out in situ in the electron microscope. The structural changes of the specimens were monitored using high-resolution electron microscopy (HREM).The amorphization of α-quartz crystals was found to progress through two morphologies: (a) nucleation and growth of amorphous nuclei with a sharp boundary with the crystalline matrix (figure 1); and (b) crystallinity lost gradually and more uniformly. Figure 2 shows a series of HREM images showing the amorphization of a tridymite crystal.

In situ high-resolution Electron Microscopy

1990 ◽  
Vol 48 (4) ◽  
pp. 512-513 ◽  
Author(s):  
Robert Sinclair
Keyword(s):  
Electron Microscopy ◽  
High Resolution ◽  
Elevated Temperatures ◽  
High Resolution Electron Microscopy ◽  
Atomic Level ◽  
Video Recorder ◽  
Resolution Electron ◽  
Imaging Conditions ◽  
Major Impediment

In recent years, there have been many dramatic recordings of dynamic behavior, taken at the atomic level by high-resolution electron microscopy. However in the majority of cases, reliance has been placed on the imaging electron beam to bring about the changes in question. There are many disadvantages to this approach, not the least of which is the lack of experimental control available to the operator. Accordingly we have developed the application of a heating holder to achieve stable elevated temperatures at which reactions can be followed under atomic imaging conditions. This article briefly reviews our progress to-date.Our microscope system is quite conventional, showing that there is no major impediment to hot-stage HREM. We have employed a Philips EM 430 ST (300kV) instrument equipped with a Gatan image pick-up device and a commercial video-recorder. The heating holder is the Philips single tilt sideentry model (PW 6592) which we have found works well up to about 875°C. Of course a double tilt holder is preferable but we overcome the tilting limitations by judicious positioning of cross-section specimens. Image stability can be achieved by heating to a temperature below that of the observation for several minutes before "ramping up" to the desired level.

Unveiling Novel Reaction Processes in Catalysis by Environmentalhrem (EHREM)

1997 ◽  
Vol 3 (S2) ◽  
pp. 617-618 ◽  
Author(s):  
Pratibha L. Gai
Keyword(s):  
Elevated Temperatures ◽  
Real Life ◽  
High Resolution Electron Microscopy ◽  
Dynamic Interactions ◽  
Lattice Image ◽  
Heterogeneous Catalytic ◽  
Resolution Electron ◽  
Heterogeneous Catalytic Processes ◽  
Reaction Processes

Dynamic interactions between gas molecule and solid surfaces are central to heterogeneous catalytic processes. Recently, we have developed a novel in-situ environmental high resolution electron microscopy (EHREM) method, capable of probing live gas-catalyst reactions at elevated temperatures directly (in-situ) on the atomic scale1. A Philips CM30 (S)TEM has been modified with an integrated environmental cell maintaining atomic resolution in controlled gas environments, upto ∼ 1000 °C. Using this method, we have studied important real-life catalysts, vanadyl pyrophosphates ((VO)2P2O7, hereafter referred to as VPO), used in n-butane oxidation to maleic anhydride (MA with end uses in furans.The catalyst samples were prepared using V2O5, anhydrous phosphoric acid in isobutyl alcohol and benzyl alcohol followed by calcination and activation. VPO is orthorhombic with a ∼ 16.59Å, b ∼ 7.76Å and c ∼ 9.58 Å . An EHREM lattice image of the fresh catalyst with electron diffraction (ED) and ‘rose’ morphology, is shown in Fig 1(a).

A study of Al2Ti precipitation in a Cu-modified Al3Ti alloy

1992 ◽  
Vol 7 (4) ◽  
pp. 876-882 ◽  
Author(s):  
L. Potez ◽  
A. Loiseau ◽  
S. Naka ◽  
G. Lapasset
Keyword(s):  
Electron Microscopy ◽  
High Resolution ◽  
Mechanical Behavior ◽  
Vickers Microhardness ◽  
High Resolution Electron Microscopy ◽  
Nucleation And Growth ◽  
Ti Alloy ◽  
Hardening Effect ◽  
Resolution Electron

An equilibrium precipitation of Al2Ti is shown to occur within a Cu-modified Al2Ti alloy having the L12 structure. This precipitation is analyzed by conventional and high resolution electron microscopy and some insights are given concerning the mechanisms of nucleation and growth of Al2Ti within the L12 matrix. In the meantime, Vickers microhardness tests have been performed as a first approach to the mechanical behavior of this alloy and the results are compared to measurements obtained in an actual single-phased L12 compound. The Al2Ti precipitation seems to have an important hardening effect.

In-Situ Studies of Epitaxial Thin-Film Growth

1964 ◽  
Vol 19 (7-8) ◽  
pp. 835-843 ◽  
Author(s):  
H. Poppa
Keyword(s):  
Film Growth ◽  
High Resolution Electron Microscopy ◽  
Thin Film Growth ◽  
Continuous Observation ◽  
Epitaxial Thin Film ◽  
Epitaxial Thin Film Growth ◽  
Resolution Electron ◽  
Substrate Surfaces ◽  
Kinetics Of

Early stages of oriented overgrowth of Ag, Au, and Pd on thin, single-crystal substrates of mica, molybdenite, Au and Pd were studied by high-resolution electron microscopy and diffraction. Cleaning of substrate surfaces and deposition of evaporated materials were conducted inside an electron microscope. High-magnification, continuous observation during growth permitted investigation of the kinetics of growth. A number of probably elementary epitaxial processes were studied in detail. Nucleation and growth behavior was examined for different supersaturations and free surface energies of substrate and overgrowth materials. The influence of alloying on growth and the spacing of parallel moiré structures was investigated.

Structure, Composition and Stability of Heterophase Boundaries

1997 ◽  
Vol 3 (S2) ◽  
pp. 673-674
Author(s):  
M. Rühle ◽  
T. Wagner ◽  
S. Bernath ◽  
J. Plitzko ◽  
C. Scheu ◽  
...  
Keyword(s):  
Electron Microscopy ◽  
Elevated Temperatures ◽  
Analytical Electron Microscopy ◽  
High Resolution Electron Microscopy ◽  
Advanced Materials ◽  
Bulk Crystals ◽  
Transmission Electron ◽  
Resolution Electron ◽  
The Stability

Heterophase boundaries play an important role in advanced materials since those materials often comprise different components. The properties of the materials depend strongly on the properties of the interface between the components. Thus, it is important to investigate the stability of the microstructure with respect to annealing at elevated temperatures. In this paper results will be presented on the structure and composition of the interfaces between Cu and (α -Al2O3. The interfaces were processed either by growing a thin Cu overlayer on α- Al2O3 in a molecular beam epitaxy (MBE) system or by diffusion bonding bulk crystals of the two constituents in an UHV chamber. To improve the adhesion of Cu to α -Al2O3 ultrathin Ti interlayers were deposited between Cu and α - Al2O3.Interfaces were characterized by different transmission electron microscopy (TEM) techniques. Quantitative high-resolution electron microscopy (QHRTEM) allows the determination of the structure (coordinates of atoms) while analytical electron microscopy (AEM) allows the determination of the composition with high spatial resolution.

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