Time-Resolved Crystallization of GeTe

1986 ◽  
Vol 74 ◽  
Author(s):  
E. Huber ◽  
E. E. Marinero
Keyword(s):  
Thin Films ◽  
Thermal Behaviour ◽  
Large Degree ◽  
Laser Pulses ◽  
Nucleation And Growth ◽  
Threshold Fluence ◽  
Conductivity Measurements ◽  
Time Resolved ◽  
Amorphous Thin Films ◽  
Fluence Regime

AbstractAmorphous thin films of GeTe were irradiated with excimer laser pulses and the subsequent crystallization was investigated utilizing simultaneous transient reflectivity and conductivity measurements. Below a threshold fluence of 15 mJ/cm2 pure thermal behaviour was found. Above that value, nucleation and growth are observed during the cooldown process. Above a fluence of 22 mJ/cm2 the films crystallize to a large degree within 200ns. Between 15 and 22 mJ/cm2 crystallite nuclei are formed (“frustrated crystallization”), and application of a subsequent pulse over areas exposed to this fluence regime leads to extremely fast crystallization (50 ns).

scholarly journals Time-Resolved Picosecond Reflectivity Study of Laser-Excited Layered Compounds

1986 ◽  
Vol 74 ◽  
Author(s):  
C. Y. Huang ◽  
A. M. Malvezzi ◽  
N. Bloembergen ◽  
F.J. Di Salvo
Keyword(s):  
Phase Transformation ◽  
Laser Pulses ◽  
High Temperature Phase ◽  
Layered Compounds ◽  
Temperature Phase ◽  
Threshold Fluence ◽  
Time Resolved ◽  
High Fluences ◽  
A Value ◽  
Pump And Probe

AbstractWe have employed the pump-and-probe technique to perform picosecond time resolved measurements of the reflectivity changes in two archetypal layered compounds, IT-TiS2 and lT-TiSe2 probed at 1.064 μm after pumping by 20 ps, .532 μm laser pulses. At the threshold fluence, ∼ 40 mJ/cm2, the reflectivity drops sharply, marking the occurrence of a phase transformation on the surface of the sample. Above threshold, the reflectivity reaches a value as low as ∼0.1 at high fluences, strongly suggesting that, like in graphite, the high temperature phase is not metallic.

Time-resolved study of back side ablated molybdenum thin films by ultrashort laser pulses

2012 ◽  
Vol 110 (1) ◽  
pp. 227-233 ◽  
Author(s):  
Dominik Bartl ◽  
Andreas Michalowski ◽  
Margit Hafner ◽  
Andreas Letsch ◽  
Stefan Nolte ◽  
...  
Keyword(s):  
Thin Films ◽  
Laser Pulses ◽  
Ultrashort Laser Pulses ◽  
Back Side ◽  
Time Resolved ◽  
Ultrashort Laser

Femtosecond Pulses as a New Photonic Source for Growing Thin Films by Pulsed-laser Deposition

2003 ◽  
Vol 780 ◽  
Author(s):  
Eric Millon ◽  
Jacques Perrière ◽  
Olivier Albert ◽  
Jean Etchepare ◽  
Chantal Boulmer-Leborgne
Keyword(s):  
Thin Films ◽  
Pulsed Laser Deposition ◽  
Pulsed Laser ◽  
Target Material ◽  
Wide Band ◽  
Laser Pulses ◽  
Growth Conditions ◽  
Laser Deposition ◽  
Time Resolved ◽  
Short Laser Pulses

AbstractThe femtosecond (fs) lasers display noticeable specificities compared with the nanosecond (ns) ones operating in the UV domain, and classically used for the pulsed-laser deposition (PLD) technique. The ultra-short laser pulses offer the feature of minimal thermal damage induced in the target material, and the very high intensities (1012-14 W/cm2) available with fs lasers are likely to allow the ablation of any kind of materials, even the wide band gap insulators.The morphology, structure, composition and properties of the films obtained by fs PLD are studied according to the experimental growth conditions, the nature of the target material, and the dynamic expansion of plasma plume. In the case of ZnO, smooth, dense and nanocrystalline films (10 to 30 nm crystallites) can be epitaxially grown on adequate substrates (i.e. sapphire). On the contrary, BaTiO3 films are formed by the random stacking of aggregates (10 to 200 nm) leading to a non negligible surface roughness,. In addition, the chemical composition of fs PLD thin films of multicomponent compound (i.e. BaTiO3) is not homogeneous, an enrichment in the lighter element being observed in the central part of the film. These properties are related to the phenomena taking place during the various steps of the process (laser-matter interaction, plasma formation, expansion) through time resolved emission spectroscopy and plume optical imaging measurements.

Application of In Situ HREM to Study Crystallization in Materials

2005 ◽  
Vol 494 ◽  
pp. 7-12
Author(s):  
R. Sinclair ◽  
Kyung Hoon Min ◽  
U. Kwon
Keyword(s):  
Electron Microscopy ◽  
Thin Films ◽  
Solid Phase ◽  
Tantalum Oxide ◽  
Nucleation And Growth ◽  
In Situ Observation ◽  
Amorphous Thin Films ◽  
Transmission Electron ◽  
Kinetics Of

A review is given of the application of in situ transmission electron microscopy to study various processes associated with the crystallization of amorphous thin films. Solid phase epitaxial regrowth of ion-implanted silicon is compared with nucleation and growth in deposited thin films. The mechanism of metal-mediated crystallization is deduced directly from high resolution recordings, and the kinetics of tantalum oxide devitrefication are obtained. The advantages of direct in situ observation are described

Fundamental Research into Thin Films in a Developing Country

1972 ◽  
Vol 30 ◽  
pp. 500-501
Author(s):  
J.A. Eades ◽  
E. Grünbaum
Keyword(s):  
Thin Films ◽  
Growth Process ◽  
Empirical Process ◽  
Nucleation And Growth ◽  
Research Groups ◽  
Film Research ◽  
Fundamental Research ◽  
Controlled Deposition ◽  
The One ◽  
The University

In the last decade and a half, thin film research, particularly research into problems associated with epitaxy, has developed from a simple empirical process of determining the conditions for epitaxy into a complex analytical and experimental study of the nucleation and growth process on the one hand and a technology of very great importance on the other. During this period the thin films group of the University of Chile has studied the epitaxy of metals on metal and insulating substrates. The development of the group, one of the first research groups in physics to be established in the country, has parallelled the increasing complexity of the field.The elaborate techniques and equipment now needed for research into thin films may be illustrated by considering the plant and facilities of this group as characteristic of a good system for the controlled deposition and study of thin films.

Investigation of ultra-thin films of YBa2Cu3O7−δ grown on MgO

1990 ◽  
Vol 48 (4) ◽  
pp. 6-7
Author(s):  
S.K. Streiffer ◽  
C.B. Eom ◽  
J.C. Bravman ◽  
T.H. Geballet
Keyword(s):  
Thin Films ◽  
Room Temperature ◽  
Deposition Process ◽  
Nucleation And Growth ◽  
Multilayer Structures ◽  
Rf Power ◽  
Oxygen Loss ◽  
Transmission Electron ◽  
Single Target ◽  
Mtorr Argon

The study of very thin (<15 nm) YBa2Cu3O7−δ (YBCO) films is necessary both for investigating the nucleation and growth of films of this material and for achieving a better understanding of multilayer structures incorporating such thin YBCO regions. We have used transmission electron microscopy to examine ultra-thin films grown on MgO substrates by single-target, off-axis magnetron sputtering; details of the deposition process have been reported elsewhere. Briefly, polished MgO substrates were attached to a block placed at 90° to the sputtering target and heated to 650 °C. The sputtering was performed in 10 mtorr oxygen and 40 mtorr argon with an rf power of 125 watts. After deposition, the chamber was vented to 500 torr oxygen and allowed to cool to room temperature. Because of YBCO’s susceptibility to environmental degradation and oxygen loss, the technique of Xi, et al. was followed and a protective overlayer of amorphous YBCO was deposited on the just-grown films.

Interface motion during recrystallization of amorphous NiSi2

1990 ◽  
Vol 48 (4) ◽  
pp. 524-525
Author(s):  
J. L. Batstone ◽  
D.A. Smith
Keyword(s):  
Thin Films ◽  
Room Temperature ◽  
Amorphous Film ◽  
Nucleation And Growth ◽  
Recrystallization Process ◽  
Amorphous Films ◽  
Interface Motion ◽  
Si Substrates ◽  
Spherical Caps ◽  
Crystal Interfaces

Recrystallization of amorphous NiSi2 involves nucleation and growth processes which can be studied dynamically in the electron microscope. Previous studies have shown thatCoSi2 recrystallises by nucleating spherical caps which then grow with a constant radial velocity. Coalescence results in the formation of hyperbolic grain boundaries. Nucleation of the isostructural NiSi2 results in small, approximately round grains with very rough amorphous/crystal interfaces. In this paper we show that the morphology of the rccrystallizcd film is dramatically affected by variations in the stoichiometry of the amorphous film.Thin films of NiSi2 were prepared by c-bcam deposition of Ni and Si onto Si3N4, windows supported by Si substrates at room temperature. The base pressure prior to deposition was 6 × 107 torr. In order to investigate the effect of stoichiomctry on the recrystallization process, the Ni/Si ratio was varied in the range NiSi1.8-2.4. The composition of the amorphous films was determined by Rutherford Backscattering.

X- ray diffraction and dielectric properties of PbSe thin films

2019 ◽  
Vol 15 (34) ◽  
pp. 1-14
Author(s):  
Bushra A. Hasan
Keyword(s):  
Thin Films ◽  
Thermal Activation ◽  
Thermal Evaporation ◽  
Thermal Activation Energy ◽  
Dielectric Constants ◽  
Conductivity Measurements ◽  
X Ray Diffraction ◽  
Thermal Evaporation Method ◽  
X Ray ◽  
Glass Substrates

Lead selenide PbSe thin films of different thicknesses (300, 500, and 700 nm) were deposited under vacuum using thermal evaporation method on glass substrates. X-ray diffraction measurements showed that increasing of thickness lead to well crystallize the prepared samples, such that the crystallite size increases while the dislocation density decreases with thickness increasing. A.C conductivity, dielectric constants, and loss tangent are studied as function to thickness, frequency (10kHz-10MHz) and temperatures (293K-493K). The conductivity measurements confirm confirmed that hopping is the mechanism responsible for the conduction process. Increasing of thickness decreases the thermal activation energy estimated from Arhinus equation is found to decrease with thickness increasing. The increase of thickness lead to reduce the polarizability α while the increasing of temperature lead to increase α.

scholarly journals Dual-shot dynamics and ultimate frequency of all-optical magnetic recording on GdFeCo

2021 ◽  
Vol 10 (1) ◽  
Author(s):  
Sicong Wang ◽  
Chen Wei ◽  
Yuanhua Feng ◽  
Hongkun Cao ◽  
Wenzhe Li ◽  
...  
Keyword(s):  
Magnetization Reversal ◽  
Energy Efficient ◽  
High Speed ◽  
Data Transfer ◽  
Laser Pulses ◽  
Time Resolved ◽  
All Optical ◽  
Fs Laser ◽  
High Speed Data ◽  
Natural Way

AbstractAlthough photonics presents the fastest and most energy-efficient method of data transfer, magnetism still offers the cheapest and most natural way to store data. The ultrafast and energy-efficient optical control of magnetism is presently a missing technological link that prevents us from reaching the next evolution in information processing. The discovery of all-optical magnetization reversal in GdFeCo with the help of 100 fs laser pulses has further aroused intense interest in this compelling problem. Although the applicability of this approach to high-speed data processing depends vitally on the maximum repetition rate of the switching, the latter remains virtually unknown. Here we experimentally unveil the ultimate frequency of repetitive all-optical magnetization reversal through time-resolved studies of the dual-shot magnetization dynamics in Gd27Fe63.87Co9.13. Varying the intensities of the shots and the shot-to-shot separation, we reveal the conditions for ultrafast writing and the fastest possible restoration of magnetic bits. It is shown that although magnetic writing launched by the first shot is completed after 100 ps, a reliable rewriting of the bit by the second shot requires separating the shots by at least 300 ps. Using two shots partially overlapping in space and minimally separated by 300 ps, we demonstrate an approach for GHz magnetic writing that can be scaled down to sizes below the diffraction limit.

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