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

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.

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In situ excimer laser irradiation as cleaning tool for solid phase epitaxy of laser crystallized polycrystalline silicon thin films

physica status solidi (a) ◽

10.1002/pssa.201330056 ◽

2013 ◽

Vol 210 (12) ◽

pp. 2729-2735 ◽

Cited By ~ 1

Author(s):

Ingmar Höger ◽

Thomas Schmidt ◽

Anja Landgraf ◽

Martin Schade ◽

Annett Gawlik ◽

...

Keyword(s):

Thin Films ◽

Laser Irradiation ◽

Excimer Laser ◽

Polycrystalline Silicon ◽

Solid Phase ◽

Solid Phase Epitaxy ◽

Silicon Thin Films ◽

Excimer Laser Irradiation

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Effects of boron doping on solid phase crystallization of in situ doped amorphous Silicon thin films prepared by electron beam evaporation

Thin Solid Films ◽

10.1016/j.tsf.2019.137639 ◽

2020 ◽

Vol 694 ◽

pp. 137639 ◽

Cited By ~ 1

Author(s):

Salar H. Sedani ◽

Ozlen F. Yasar ◽

Mehmet Karaman ◽

Rasit Turan

Keyword(s):

Thin Films ◽

Electron Beam ◽

Amorphous Silicon ◽

Solid Phase ◽

Boron Doping ◽

Electron Beam Evaporation ◽

Solid Phase Crystallization ◽

Silicon Thin Films

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Reversible disorder-order transitions in atomic crystal nucleation

Science ◽

10.1126/science.aaz7555 ◽

2021 ◽

Vol 371 (6528) ◽

pp. 498-503

Author(s):

Sungho Jeon ◽

Taeyeong Heo ◽

Sang-Yeon Hwang ◽

Jim Ciston ◽

Karen C. Bustillo ◽

...

Keyword(s):

Early Stage ◽

Nucleation Theory ◽

Crystal Nucleation ◽

Classical Nucleation Theory ◽

Gold Nanocrystals ◽

Size Dependent ◽

In Situ Electron Microscopy ◽

Nucleation Mechanisms ◽

Structural Fluctuations

Nucleation in atomic crystallization remains poorly understood, despite advances in classical nucleation theory. The nucleation process has been described to involve a nonclassical mechanism that includes a spontaneous transition from disordered to crystalline states, but a detailed understanding of dynamics requires further investigation. In situ electron microscopy of heterogeneous nucleation of individual gold nanocrystals with millisecond temporal resolution shows that the early stage of atomic crystallization proceeds through dynamic structural fluctuations between disordered and crystalline states, rather than through a single irreversible transition. Our experimental and theoretical analyses support the idea that structural fluctuations originate from size-dependent thermodynamic stability of the two states in atomic clusters. These findings, based on dynamics in a real atomic system, reshape and improve our understanding of nucleation mechanisms in atomic crystallization.

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In situ HREM of interface interactions

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100149982 ◽

1993 ◽

Vol 51 ◽

pp. 830-831

Author(s):

Robert Sinclair ◽

Toyohiko J. Konno

Keyword(s):

Amorphous Material ◽

Equilibrium Phase ◽

High Resolution Electron Microscopy ◽

Atomic Scale ◽

Orientation Relationships ◽

Interface Reactions ◽

Diffusion Controlled ◽

Resolution Electron

We have applied in situ high-resolution electron microscopy (HREM) to the study of interface reactions, particularly in metal-semiconductor systems. There is contrasting behavior whether or not the manufactured interface undergoes a chemical reaction. The in situ technique allows determination of the reaction mechanisms on an atomic scale.Reactive interfaces are characterized by systems in which new chemical compounds are formed (e.g., silicides for metal-silicon interfaces, metal gallides and arsenides for GaAs, etc.). We found that the equilibrium phase formation is often preceded by a solid-state amorphization reaction. In situ observations allow very precise measurement of the reaction rate in a sufficient temperature range to confirm that this process is diffusion controlled. Crystallization of the amorphous material can be followed as well as the development of any crystallographic orientation relationships. A ledge growth mechanism can easily be distinguished from a random process.It might be expected that non-reactive interfaces are stable upon heating.

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Nonclassical Nucleation—Role of Metastable Intermediate Phase in Crystal Nucleation: An Editorial Prefix

Crystals ◽

10.3390/cryst11020174 ◽

2021 ◽

Vol 11 (2) ◽

pp. 174

Author(s):

Fajun Zhang ◽

José A. Gavira ◽

Geun Woo Lee ◽

Dirk Zahn

Keyword(s):

Intermediate Phase ◽

Solid Phase ◽

Early Stage ◽

Order Parameters ◽

Nucleation Theory ◽

Crystal Nucleation ◽

Classical Nucleation Theory ◽

Supersaturated Solution ◽

Liquid Phases

Classical nucleation theory (CNT), which was established about 90 years ago, represents the most commonly used theory in describing nucleation processes. For a fluid-to-solid phase transition, CNT states that the solutes in a supersaturated solution reversibly form small clusters. Once a cluster reaches its critical size, it becomes thermodynamically stable and is favored for further growth. One of the most important assumptions of CNT is that the nucleation process is described by one reaction coordinate and all order parameters proceed simultaneously. Recent studies in experiments, computer simulations, and theory have revealed nonclassical features in the early stage of nucleation. In particular, the decoupling of order parameters involved during a fluid-to-solid transition leads to the so-called two-step nucleation mechanism, in which a metastable intermediate phase (MIP) exists in parallel to the initial supersaturated solution and the final crystals. These MIPs can be high-density liquid phases, mesoscopic clusters, or preordered states. In this Special Issue, we focus on the role of the various MIPs in the early stage of crystal nucleation of organic materials, metals and alloys, aqueous solutions, minerals, colloids, and proteins, and thus on various scenarios of nonclassical pathways of crystallization.

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Structural and Phase Transformations in Thin Film Ti-Aluminides and Ti/Al Multilayers

MRS Proceedings ◽

10.1557/proc-434-63 ◽

1996 ◽

Vol 434 ◽

Cited By ~ 2

Author(s):

R. Banerjee ◽

S. Swaminathan ◽

R. Wheeler ◽

H. L. Fraser

Keyword(s):

Electron Microscopy ◽

Thin Films ◽

Layer Thickness ◽

High Resolution Electron Microscopy ◽

Silicon Substrates ◽

Two Phase ◽

Transmission Electron ◽

Resolution Electron ◽

Sputter Deposited

AbstractMultilayered Ti/Al thin films (with nominally equal layer thickness of Ti and Al) have been sputter deposited on oxidized silicon substrates at room temperature. Transmission electron microscopy (TEM) and high resolution electron microscopy have been used to characterize the structure of these multilayers as a function of the layer thickness. Ti changed from an hcp to an fcc and back to an hcp structure on reduction of the layer thickness. Al too changed from an fcc to an hcp structure at a layer thickness of 2.5 nm. The observed structural transitions have been explained on the basis of the Redfield-Zangwill model. Subsequently Ti-aluminide thin films were deposited using a γ-TiAl target. These films were found to be amorphous in the as-deposited condition with crystallites of α-Ti(Al) embedded in the amorphous matrix. On annealing under a protective Ar atmosphere at a temperature of 550 °C, the Ti-aluminide film crystallized into a nanocrystalline two phase microstructure consisting of γ-TiAl and α2-Ti3Al. The crystallization of the aluminide film has been investigated in detail by in-situ annealing experiments on a hot stage in the TEM. The results of this investigation have been discussed in this paper.

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HREM imaging of PtSn4/PtSn2 interfaces in Pt-Sn thin films

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100171420 ◽

1994 ◽

Vol 52 ◽

pp. 738-739

Author(s):

D. C. Dufner

Keyword(s):

Thin Films ◽

High Resolution Electron Microscopy ◽

Carbon Films ◽

Alloy Formation ◽

State University ◽

Arizona State University ◽

Resolution Electron ◽

Interdiffusion Process ◽

20 Nm

High resolution electron microscopy (HREM) is a very useful technique for studying intermetallic alloy formation resulting from the interdiffusion of metals in thin films. In this work, reactions between Pt and Sn thin films are studied to elucidate mechanisms for structural and compositional changes during the interdiffusion process.Thin film specimens are prepared by the two-film method introduced by Shiojiri et al. Approximately 50 nm of Pt are vacuum-deposited onto holey carbon films mounted on 3mm diameter TEM grids. Sn films with an average thickness of 20 nm are created by evaporating Sn at rates of 1.5-3.0 nm/sec onto air-cleaved KBr substrates. The Sn films are then wet-stripped and collected on the Pt-coated holey carbon grids. A thin carbonaceous contamination layer exists between the metal films to prevent the onset of interdiffusion until the specimens are heated in situ in the TEM.TEM observations are carried out on the JEOL 2010 200kV TEM at Texas A&M University and the JEOL 4000EX 400kV TEM at Arizona State University.

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In Situ Hrem Observations of Crystallization in LPCVD Amorphous Silicon

MRS Proceedings ◽

10.1557/proc-182-191 ◽

1990 ◽

Vol 182 ◽

Cited By ~ 11

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.

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In Stlo High Resolution Electron Microscopy for Interface Studies

MRS Proceedings ◽

10.1557/proc-82-379 ◽

1986 ◽

Vol 82 ◽

Author(s):

M. A. Parker ◽

R. Sinclair

Keyword(s):

Electron Microscopy ◽

High Resolution ◽

Solid Phase ◽

High Resolution Electron Microscopy ◽

Kinetic Measurements ◽

High Voltage Electron Microscopy ◽

Interface Reactions ◽

Voltage Electron ◽

Transmission Electron ◽

Resolution Electron

In situ kinetic measurements on the rate of solid—phase epitaxial regrowth of silicon in a conventional transmission electron microscope are described. The data compare well with those established for the sane material by high voltage electron microscopy and by Rutherford backscattering spectroscopy. High—resolution imaging at the same time provides direct information on atomic mechanisms. It is anticipated that this will beccme a more highly developed procedure in due course, especially for studies of interface reactions.

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