The Melting of Amorphous Si

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

Journal of Materials Research ◽

10.1557/jmr.1987.0648 ◽

1987 ◽

Vol 2 (5) ◽

pp. 648-680 ◽

Cited By ~ 45

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.

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Thermodynamic and Kinetic Studies of Pulsed-Laser Annealing from Transient Conductivity Measurements

MRS Proceedings ◽

10.1557/proc-35-53 ◽

1984 ◽

Vol 35 ◽

Cited By ~ 13

Author(s):

P.S. Peercy ◽

Michael O. Thompson

Keyword(s):

Melting Temperature ◽

Silicon Germanium ◽

Laser Annealing ◽

Pulsed Laser ◽

Kinetic Studies ◽

Alloy System ◽

Velocity Versus ◽

Solidification Velocity ◽

Molten Layer ◽

Amorphous Si

ABSTRACTSimultaneous measurements of the transient conductance and time-dependent surface reflectance of the melt and solidification dynamics produced by pulsed laser irradiation of Si are reviewed. These measurements demonstrate that the melting temperature of amorphous Si is reduced 200 ± 50 K from that of crystalline Si and that explosive crystallization in amorphous Si is mediated by a thin (≤ 20 nm) molten layer that propagates at ~ 15 m/sec. Studies with 3.5 nsec pulses permit an estimate of the dependence of the solidification velocity on undercooling. Measurements of the effect of As impurities on the solidification velocity demonstrate that high As concentrations decrease the melting temperature of Si (~ 150 K for 7 at.%), which can result in surface nucleation to produce buried melts. Finally, the silicon-germanium alloy system is shown to be an ideal model system for the study of superheating and undercooling. The Si50Ge50 alloy closely models amorphous Si, and measurements of layered Si-Ge alloy structures indicate superheating up to 120 K without nucleation of internal melts. The change in melt velocity with superheating yields a velocity versus superheating of 17 ± 3 k/m/sec.

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Melting Temperature and Explosive Crystallization of Amorphous Silicon during Pulsed Laser Irradiation

Physical Review Letters ◽

10.1103/physrevlett.52.2360 ◽

1984 ◽

Vol 52 (26) ◽

pp. 2360-2363 ◽

Cited By ~ 470

Author(s):

Michael O. Thompson ◽

G. J. Galvin ◽

J. W. Mayer ◽

P. S. Peercy ◽

J. M. Poate ◽

...

Keyword(s):

Amorphous Silicon ◽

Laser Irradiation ◽

Melting Temperature ◽

Pulsed Laser ◽

Explosive Crystallization ◽

Pulsed Laser Irradiation

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Interface Velocity Transients During Melting of a-Si/C-Si Thin Films

MRS Proceedings ◽

10.1557/proc-100-519 ◽

1988 ◽

Vol 100 ◽

Cited By ~ 5

Author(s):

J. Y. Tsao ◽

M. J. Aziz ◽

P. S. Peercy ◽

M. O. Thompson

Keyword(s):

Thin Films ◽

Steady State ◽

Pulsed Laser ◽

Interface Velocity ◽

Interface Temperature ◽

Laser Melting ◽

Systematic Procedure ◽

Solid Interface ◽

Amorphous Si ◽

Si Films

ABSTRACTWe report transient conductance measurements of liquid/solid interface velocities during pulsed laser melting of amorphous Si (a-Si) films on crystalline Si (c-Si), and a more accurate, systematic procedure for analyzing these measurements than described in previous work [1]. From these analyses are extracted relations between the melting velocities of a-Si and c-Si at a given interface temperature, and between the temperatures during steady-state melting of a-Si and c-Si at a given interface velocity.

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Dynamics of Rapid Solidification in Silicon

MRS Proceedings ◽

10.1557/proc-74-15 ◽

1986 ◽

Vol 74 ◽

Cited By ~ 6

Author(s):

P. S. Peercy ◽

Michael O. Thompson ◽

J. Y. Tsao

Keyword(s):

Transition State ◽

Large Deviations ◽

Layer Thickness ◽

Melting Temperature ◽

Amorphous Layer ◽

Fine Grained ◽

Explosive Crystallization ◽

Explosive Transformation ◽

Amorphous Si ◽

Moving Liquid

AbstractReal-time techniques were used to study rapid melt and solidification dynamics in silicon. In crystalline Si, the interface response function was characterized and found to be asymmetric for large deviations from the melting temperature, which will require reevaluation of conventional transition state treatments of melt and solidification. In amorphous Si, the mechanism of explosive crystallization was studied. The explosive transformation is mediated by a buried liquid layer, and detailed measurements have led to the suggestion that polycrystalline Si nucleates at the moving liquid-amorphous interface. For certain conditions, this process could yield fine-grained polycrystalline Si; for other conditions it permits epitaxial regrowth from the underlying crystalline Si for maximum melt thickness much less than the original amorphous layer thickness.

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Dynamics of Rapid Solidification in Silicon

MRS Proceedings ◽

10.1557/proc-80-39 ◽

1986 ◽

Vol 80 ◽

Author(s):

P. S. Peercy ◽

Michael O. Thompson ◽

J. Y. Tsao

Keyword(s):

Transition State ◽

Large Deviations ◽

Layer Thickness ◽

Melting Temperature ◽

Amorphous Layer ◽

Fine Grained ◽

Explosive Crystallization ◽

Explosive Transformation ◽

Amorphous Si ◽

Moving Liquid

AbstractReal-time techniques were used to study rapid melt and solidification dynamics in silicon. In crystalline Si, the interface response function was characterized and found to be asymmetric for large deviations from the melting temperature, which will require reevaluation of conventional transition state treatments of melt and solidification. In amorphous Si, the mechanism of explosive crystallization was studied. The explosive transformation is mediated by a buried liquid layer, and detailed measurements have led to the suggestion that polycrystalline Si nucleates at the moving liquid-amorphous interface. For certain conditions, this process could yield fine-grained polycrystalline Si; for other conditions it permits epitaxial regrowth from the underlying crystalline Si for maximum melt thickness much less than the original amorphous layer thickness.

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

IEEJ Transactions on Electronics Information and Systems ◽

10.1541/ieejeiss.135.1066 ◽

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

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

ChemPhysChem ◽

10.1002/cphc.202001000 ◽

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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The Al Doping Effect on Epitaxial (In,Mn)As Dilute Magnetic Semiconductors Prepared by Ion Implantation and Pulsed Laser Melting

Materials ◽

10.3390/ma14154138 ◽

2021 ◽

Vol 14 (15) ◽

pp. 4138

Author(s):

Ye Yuan ◽

Yufang Xie ◽

Ning Yuan ◽

Mao Wang ◽

René Heller ◽

...

Keyword(s):

Curie Temperature ◽

Ion Implantation ◽

Diluted Magnetic Semiconductors ◽

Laser Annealing ◽

Magnetic Semiconductors ◽

Dilute Magnetic Semiconductors ◽

Pulsed Laser ◽

Laser Melting ◽

Co Doping ◽

Diluted Magnetic

One of the most attractive characteristics of diluted ferromagnetic semiconductors is the possibility to modulate their electronic and ferromagnetic properties, coupled by itinerant holes through various means. A prominent example is the modification of Curie temperature and magnetic anisotropy by ion implantation and pulsed laser melting in III–V diluted magnetic semiconductors. In this study, to the best of our knowledge, we performed, for the first time, the co-doping of (In,Mn)As diluted magnetic semiconductors by Al by co-implantation subsequently combined with a pulsed laser annealing technique. Additionally, the structural and magnetic properties were systematically investigated by gradually raising the Al implantation fluence. Unexpectedly, under a well-preserved epitaxial structure, all samples presented weaken Curie temperature, magnetization, as well as uniaxial magnetic anisotropies when more aluminum was involved. Such a phenomenon is probably due to enhanced carrier localization introduced by Al or the suppression of substitutional Mn atoms.

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