Time Resolved Measurements of Interface Dynamics During Pulsed Laser Melting Observed by Transient Conductance

1983 ◽  
Vol 13 ◽  
Author(s):  
Michael O. Thompson ◽  
G. J. Galvin
Keyword(s):  
Computer Simulation ◽  
Critical Velocity ◽  
Uv Irradiation ◽  
Thermal Model ◽  
Pulsed Laser ◽  
Laser Melting ◽  
Interface Dynamics ◽  
Time Resolved ◽  
Simulation Based ◽  
Conductance Technique

ABSTRACTThe transient conductance technique has been used in a detailed study of the liquid-solid interface dynamics during pulsed laser melting of Si and silicon-on-sapphire. Average melt and regrowth velocities, as well as the maximum melt depth, can be obtained with the technique. The measurements are found to agree well with a computer simulation based on a thermal model of the melt and subsequent solidification. The melt-in velocity has been observed to exceed 200 m/sec. Under 2.5 ns UV irradiation, the critical velocity for amorphization of <100> Si has been measured at 15 m/sec.

Solidification of highly undercooled liquid silicon produced by pulsed laser melting of ion-implanted amorphous silicon: Time-resolved and microstructural studies

1987 ◽  
Vol 2 (5) ◽  
pp. 648-680 ◽  
Author(s):  
D. H. Lowndes ◽  
S. J. Pennycook ◽  
G. E. Jellison ◽  
S. P. Withrow ◽  
D. N. Mashburn
Keyword(s):  
Pulsed Laser ◽  
Optical Measurements ◽  
Undercooled Liquid ◽  
Laser Melting ◽  
Time Resolved ◽  
Fine Grained ◽  
Explosive Crystallization ◽  
Epitaxial Regrowth ◽  
Surface Melt ◽  
Melt Duration

Nanosecond resolution time-resolved visible (632.8 nm) and infrared (1152 nm) reflectivity measurements, together with structural and Z-contrast transmission electron microscope (TEM) imaging, have been used to study pulsed laser melting and subsequent solidification of thick (190–410 nm) amorphous (a) Si layers produced by ion implantation. Melting was initiated using a KrF (248 nm) excimer laser of relatively long [45 ns full width half maximum (FWHM)] pulse duration; the microstructural and time-resolved measurements cover the entire energy density (E1) range from the onset of melting (at ∼ 0.12J/cm2) up to the onset of epitaxial regrowth (at ∼ 1.1 J/cm2). At low E1 the infrared reflectivity measurements were used to determine the time of formation, the velocity, and the final depth of “explosively” propagating buried liquid layers in 410 nm thick a-Si specimens that had been uniformly implanted with Si, Ge, or Cu over their upper ∼ 300 nm. Measured velocities lie in the 8–14 m/s range, with generally higher velocities obtained for the Ge- and Cu-implanted “a-Si alloys.” The velocity measurements result in an upper limit of 17 (± 3) K on the undercooling versus velocity relationship for an undercooled solidfying liquid-crystalline Si interface. The Z-contrast scanning TEM measurements of the final buried layer depth were in excellent agreement with the optical measurements. The TEM study also shows that the “fine-grained polycrystalline Si” region produced by explosive crystallization of a-Si actually contains large numbers of disk-shaped Si flakes that can be seen only in plan view. These Si flakes have highly amorphous centers and laterally increasing crystallinity; they apparently grow primarily in the lateral direction. Flakes having this structure were found both at the surface, at low laser E1, and also deep beneath the surface, throughout the “fine-grained poly-Si” region formed by explosive crystallization, at higher E1. Our conclusion that this region is partially amorphous (the centers of flakes) differs from earlier results. The combined structural and optical measurements suggest that Si flakes nucleate at the undercooled liquid-amorphous interface and are the crystallization events that initiate explosive crystallization. Time-resolved reflectivity measurements reveal that the surface melt duration of the 410 nm thick a-Si specimens increases rapidly for 0.3E1 <0.6 J/cm2, but then remains nearly constant for E1 up to ∼ 1.0 J/cm2. For 0.3 < E1 < 0.6 J/cm2 the reflectivity exhibits a slowly decaying behavior as the near-surface pool of liquid Si fills up with growing large grains of Si. For higher E1, a flat-topped reflectivity signal is obtained and the microstructural and optical studies together show that the principal process occurring is increasingly deep melting followed by more uniform regrowth of large grains back to the surface. However, cross-section TEM shows that a thin layer of fine-grained poly-Si still is formed deep beneath the surface for E1<0.9 J/cm2, implying that explosive crystallization occurs (probably early in the laser pulse) even at these high E1 values. The onset of epitaxial regrowth at E1 = 1.1 J/cm2 is marked by a slight decrease in surface melt duration.

Congruent Melting Temperatures of Si-As Alloys Measured During Pulsed-Laser Melting and Rapid Solidification

1992 ◽  
Vol 279 ◽  
Author(s):  
J. A. Kittl ◽  
R. Reitano ◽  
M. J. Aziz ◽  
D. P. Brunco ◽  
M. O. Thompson
Keyword(s):  
Partition Coefficient ◽  
Temperature Measurement ◽  
Rutherford Backscattering Spectrometry ◽  
Pulsed Laser ◽  
Heat Of Fusion ◽  
Interface Temperature ◽  
Congruent Melting ◽  
Laser Melting ◽  
Time Resolved ◽  
Melting Temperatures

ABSTRACTThe solidification of Si-As alloys induced by pulsed laser melting was studied at regrowth velocities where the partition coefficient is close to unity. The congruent melting temperatures, TO, of Si-As alloys were determined using a temperature measurement technique developed for this work, and were confirmed with TOmeasurements using three other methods. The time-resolved temperature measurement uses a thin-film platinum thermistor, below and electrically isolated from the Si-As alloy layer, to directly measure the temperature during solidification. This, combined with measurements of transient conductance of the Si-As alloy, time-resolved reflectivity and Rutherford Backscattering Spectrometry, permitted the determination of the solid-liquid interface temperature, velocity and partition coefficient, the latent heat of fusion and TO for Si - 4.5 at. % As and Si - 9 at. % As alloys.

Time‐resolved x‐ray study of Ge during pulsed laser melting

1988 ◽  
Vol 52 (21) ◽  
pp. 1785-1787 ◽  
Author(s):  
J. Z. Tischler ◽  
B. C. Larson ◽  
D. M. Mills
Keyword(s):  
Pulsed Laser ◽  
Laser Melting ◽  
Time Resolved ◽  
X Ray

Time-Resolved Measurements of Solidification and Undercooling in Metals and Alloys

1989 ◽  
Vol 157 ◽  
Author(s):  
Harry A. Atwater ◽  
Jeffrey A. West ◽  
Patrick M. Smith ◽  
M.J. Aziz ◽  
J.Y. Tsao ◽  
...  
Keyword(s):  
Electrical Resistivity ◽  
Heat Flow ◽  
Rapid Solidification ◽  
Pulsed Laser ◽  
Metal Films ◽  
Laser Melting ◽  
Time Resolved ◽  
Resistivity Measurements ◽  
Planar Crystal

ABSTRACTWe have performed nanosecond-resolution measurements of the lateral electrical resistivity of thin metal films on insulating substrates. Comparison of transient resistivity measurements with optical reflectivity measurements and heat-flow calculations permits the determination of the position and velocity of a planar crystal/melt interface, and an estimate of undercooling during pulsed laser melting of metals. We report detailed results for rapid solidification of Ni, including the observation of hypercooling of .liquid Ni.

Overheating and Undercooling in Silicon During Pulsed-Laser Irradiation

1984 ◽  
Vol 35 ◽  
Author(s):  
B. C. Larson ◽  
J. Z. Tischler ◽  
D. M. Mills
Keyword(s):  
Pulsed Laser ◽  
Laser Pulses ◽  
High Energy ◽  
X Ray Diffraction ◽  
Laser Melting ◽  
Time Resolved ◽  
Synchrotron Source ◽  
X Ray ◽  
Krf Excimer Laser ◽  
Pulsed Laser Irradiation

ABSTRACTWe have used time-resolved x-ray diffraction measurements of thermal expansion induced strain to measure overheating and undercooling in <100> and <111> oriented silicon during pulsed laser melting and regrowth. 249 nm (KrF) excimer laser pulses of 1.2 J/cm2 energy density and 25 ns FWHM were synchronized with x-ray pulses from the Cornell High Energy Synchrotron Source (CHESS) to carry out Bragg profile measurements with ±2 ns time resolution. Combined overheating and undercooling values of 120 ± 30 K and 45 ± 20 K were found for the <111> and <100> orientations, respectively, and these values have been used to obtain information on the limiting regrowth velocities for silicon.

Time‐resolved temperature measurements during rapid solidification of Si‐As alloys induced by pulsed‐laser melting

1993 ◽  
Vol 73 (8) ◽  
pp. 3725-3733 ◽  
Author(s):  
J. A. Kittl ◽  
R. Reitano ◽  
M. J. Aziz ◽  
D. P. Brunco ◽  
M. O. Thompson
Keyword(s):  
Rapid Solidification ◽  
Pulsed Laser ◽  
Temperature Measurements ◽  
Laser Melting ◽  
Time Resolved

Submicrometer-sized Spherical Iron Oxide Particles Fabricated by Pulsed Laser Melting in Liquid

2015 ◽  
Vol 135 (9) ◽  
pp. 1066-1070
Author(s):  
Yoshie Ishikawa ◽  
Naoto Koshizaki ◽  
Alexander Pyatenko
Keyword(s):  
Iron Oxide ◽  
Pulsed Laser ◽  
Iron Oxide Particles ◽  
Laser Melting ◽  
Oxide Particles

Reduction Mechanism of Transition Metal Oxide Particles in Thermally Induced Nanobubbles by Pulsed Laser Melting in Ethanol

ChemPhysChem ◽  
2021 ◽  
Author(s):  
Kentaro Suehara ◽  
Ryosuke Takai ◽  
Yoshie Ishikawa ◽  
Naoto Koshizaki ◽  
Kazunobu Omura ◽  
...  
Keyword(s):  
Transition Metal ◽  
Metal Oxide ◽  
Pulsed Laser ◽  
Transition Metal Oxide ◽  
Reduction Mechanism ◽  
Laser Melting ◽  
Thermally Induced ◽  
Oxide Particles
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