Fundamental Aspects of High Speed Crystal Growth from the Melt

1984 ◽  
Vol 35 ◽  
Author(s):  
A.G. Cullis
Keyword(s):  
Crystal Growth ◽  
High Speed ◽  
Defect Formation ◽  
Solid Phase ◽  
Amorphous Material ◽  
Amorphous Solid ◽  
Growth Behaviour ◽  
Amorphous Si ◽  
Amor Phization ◽  
Melting And Solidification

ABSTRACTAdvances in the study of high speed crystal growth from the melt are reviewed, with special emphasis on the fast melting and solidification of silicon achieved by use of Q-switched laser radiation pulses. Rapid melting of amorphous Si is confirmed to yield a liquid undercooled by several hundred Kelvins and, under suitable conditions, explosive crystal growth processes can occur. The latter involve the self-sustaining propagation of melt bands buried within the initially amorphous material. When the highest quench-rate conditions are established melting of even crystalline Si can yield a final amorphous solid phase. This breakdown in crystal growth is orientation dependent and can give regimes of crystal defect formation when amor-phization does not take place. The processes which characterize this limiting growth behaviour are discussed.

Studies of Ultra-High Speed Silicon Crystal Growth From The Melt By Use of Conventional and High Resolution Transmission Electron Microscopy

1985 ◽  
Vol 43 ◽  
pp. 22-25
Author(s):  
A. G. Cullis
Keyword(s):  
Electron Microscopy ◽  
Crystal Growth ◽  
High Resolution ◽  
High Speed ◽  
Solid Phase ◽  
Silicon Crystal ◽  
Amorphous Solid ◽  
Orientation Dependence ◽  
Transmission Electron ◽  
Resolution Imaging

Fast melting and solidification of semiconductors by use of Q-switched laser irradiation techniques has provided, during the last few years, a large amount of information on novel high speed crystal growth processes. Under the highest quench rate conditions, the motion of the final solidification interface can be so rapid (many metres per second) that atomic ordering processes are overwhelmed and either defective crystal or even the amorphous solid phase is formed. Most work in this area has been carried out on elemental Si and electron microscopy of solidification structures has played an essential analytical role through both conventional and high resolution imaging studies. The present paper will outline recent progress which has been made in understanding the crystallographic orientation dependence of high-speed growth phenomena.

Epitaxy and Nucleation in Cu and Ag Doped Amorphous Si

1990 ◽  
Vol 205 ◽  
Author(s):  
J. S. Custer ◽  
Michael O. Thompson ◽  
D. J. Eaglesham ◽  
D. C. Jacobson ◽  
J. M. Poate ◽  
...  
Keyword(s):  
Solid Phase ◽  
Amorphous Material ◽  
Intrinsic Rate ◽  
Amorphous Layer ◽  
Solid Phase Epitaxy ◽  
Small Deviations ◽  
Random Nucleation ◽  
Low Concentrations ◽  
Critical Metal ◽  
Amorphous Si

AbstractThe competition between solid phase epitaxy and random nucleation during thermal annealing of amorphous Si implanted with the fast diffusers Cu and Ag has been studied. For low concentrations of these impurities, solid phase epitaxy proceeds with small deviations from the intrinsic rate and with the impurity remaining in the shrinking amorphous layer. At a critical metal concentration in the amorphous layer of ∼ 0.12 at.% rapid random nucleation occurs, halting epitaxy and transforming the remaining amorphous material to polycrystalline Si via grain growth. The nucleation rate is at least 8 orders of magnitude greater than the intrinsic homogeneous rate. At higher Cu concentrations nucleation is observed below the temperature needed for epitaxy (400°C). This nucleation, clearly caused by the presence of Cu or Ag in the layer, may be induced by the impurities exceeding the absolute stability concentration and starting to phase separate, leading to enhanced crystal Si nucleation in the metal rich regions.

Ge+ Preamorphization of Si: Effects of Dose and Very Low Temperature Thermal Treatment on Extended Defect Formation During Subsequent Spe

1985 ◽  
Vol 52 ◽  
Author(s):  
E. Myers ◽  
G. A. Rozgonyi ◽  
D. K. Sadana ◽  
W. Maszara ◽  
J. J. Wortman ◽  
...  
Keyword(s):  
Phase Transition ◽  
Low Temperature ◽  
Defect Formation ◽  
Solid Phase ◽  
Amorphous Material ◽  
Dose Range ◽  
Amorphous Layer ◽  
Extended Defect ◽  
Transmission Electron ◽  
Very Low Temperature

ABSTRACTCross-section transmission electron microscopy (X-TEM) has been used to illustrate the amornhous/ crystalline (a/c) micromorphology dependence of various low dose Ge+ preamorphizatlon implants in Si. Ge+ Implants were done at room _emperature at energies of 150 and 300 keV in the dose range of 1 to 9E14 cm−2. These implants result in the formation of either a buried or a continuous amorphous layer, with rough a/c interfaces. Nucleation of spanning “hairpin” dislocations during subsequent solid phase epltaxy (SPE) regrowth is known to be related to rough a/c interface morphology. Very low temperature anneals (VLTA),less than 500°C where the rate of SPE is minimal, were utilized to sharpen rough a/c interfaces prior to subsequent SPE regrowth. Sharpening of rough a/c interfaces is shown to result from an unexpected reverse crystalline to amorphous phase transition. This reverse phase transition results in the dissolution of detached microcrystallltes located within the amorphous layer near the a/c interface. Utilization of VLTA interfacial smoothing prior to SPE regrowth therfore, results in the reduction of residual spanning “hairpin” dislocations along with homogenization of the amorphous material.

Free-Energy Barrier to Crystallite Nucleation in Solid-Phase Crystallized Poly-Silicon Thin Films

1997 ◽  
Vol 472 ◽  
Author(s):  
Hideya Kumomi ◽  
Frank G. Shi
Keyword(s):  
Thin Films ◽  
Free Energy ◽  
Energy Barrier ◽  
Solid Phase ◽  
Free Energy Barrier ◽  
Solid Phase Crystallization ◽  
Silicon Thin Films ◽  
Nucleation Barrier ◽  
Amorphous Si ◽  
Amor Phization

ABSTRACTWe introduce a non-Arrhenius method for measuring free-energy barrier to nucleation, W*, directly from size distribution of crystallites. W* is determined independent of any model for the nucleation barrier and independent of energy barrier to growth. The method is applicable to three-dimensionally growing crystallites, planar crystallites in thin films, and both compact and fractal crystallites. We apply the method to dendritic crystallites obtained by solid-phase crystallization of amorphous Si thin films into which Si+ ions are implanted at various conditions prior to the isothermal annealing. The ion implantation suppresses the nucleation of the crystallites and enhances the crystallite size of the resulting polycrystalline films. The directly measured W* increases as the accelerating energy or the dose of the Si+ ions increases. This result suggests that the observed suppression of the nucleation could not be accounted for simply by the amor-phization of the preexisting crystallites by the ion bombardment.

Ultra-High Speed Solidification and Crystal Growth in Transiently Molten Semiconductor Layers

1983 ◽  
Vol 13 ◽  
Author(s):  
A.G. Cullis
Keyword(s):  
Crystal Growth ◽  
Low Temperature ◽  
Thermodynamic Properties ◽  
High Speed ◽  
Amorphous Solids ◽  
Undercooled Liquid ◽  
Laser Melting ◽  
Amorphous Phases ◽  
Low Viscosity ◽  
Amorphous Si

ABSTRACTThe use of Q-switched laser melting techniques to investigate new rapid solidification phenomena is described. It has been found that Si, Ge, GaP and GaAs can give rise to orientation dependent, kinetically-controlled defect generation processes during fast recrystallization from the melt. Indeed, these materials yield amorphous phases at sufficiently high solidification rates. Ultra-fast pulsed melting permits the study of the basic thermodynamic properties of amorphous solids. It is shown that amorphous Si melts to give a normal, low viscosity, undercooled liquid and that novel explosive crystal growth processes can occur in this low temperature regime.

High-angle electron scattering from amorphous silicon

1995 ◽  
Vol 53 ◽  
pp. 162-163
Author(s):  
M. Libera ◽  
J.A. Ott ◽  
K. Siangchaew ◽  
L. Tsung
Keyword(s):  
Electron Scattering ◽  
Amorphous Material ◽  
Structural Defects ◽  
Constant Thickness ◽  
High Angle ◽  
Fast Electrons ◽  
Angle Scattering ◽  
Stem Image ◽  
Amorphous Si ◽  
Thermal Vibrations

Channeling occurs when fast electrons follow atomic strings in a crystal where there is a minimum in the potential energy (1). Channeling has a strong effect on high-angle scattering. Deviations in atomic position along a channel due to structural defects or thermal vibrations increase the probability of scattering (2-5). Since there are no extended channels in an amorphous material the question arises: for a given material with constant thickness, will the high-angle scattering be higher from a crystal or a glass?Figure la shows a HAADF STEM image collected using a Philips CM20 FEG TEM/STEM with inner and outer collection angles of 35mrad and lOOmrad. The specimen (6) was a cross section of singlecrystal Si containing: amorphous Si (region A), defective Si containing many stacking faults (B), two coherent Ge layers (CI; C2), and a contamination layer (D). CBED patterns (fig. lb), PEELS spectra, and HAADF signals (fig. lc) were collected at 106K and 300K along the indicated line.

Geometrical design of a crystal growth system guided by a machine learning algorithm

CrystEngComm ◽  
2021 ◽  
Author(s):  
Wancheng Yu ◽  
Can Zhu ◽  
Yosuke Tsunooka ◽  
Wei Huang ◽  
Yifan Dang ◽  
...  
Keyword(s):  
Machine Learning ◽  
Crystal Growth ◽  
High Speed ◽  
Learning Algorithm ◽  
Computational Techniques ◽  
Machine Learning Algorithm ◽  
Geometrical Design ◽  
Large Numbers ◽  
Growth System ◽  
Speed Method

This study proposes a new high-speed method for designing crystal growth systems. It is capable of optimizing large numbers of parameters simultaneously which is difficult for traditional experimental and computational techniques.

Molecular-Dynamics Simulations of Recrystallization Processes in Silicon: Nucleation and Crystal Growth in the Solid-Phase and Melt

2019 ◽  
Vol 3 (8) ◽  
pp. 207-213
Author(s):  
Teruaki Motooka ◽  
Shinji Munetoh ◽  
Ryuzo Kishikawa ◽  
Takahide Kuranaga ◽  
Tomohiko Ogata ◽  
...  
Keyword(s):  
Molecular Dynamics ◽  
Crystal Growth ◽  
Molecular Dynamics Simulations ◽  
Solid Phase ◽  
Dynamics Simulations

Kinetics of solid phase epitaxy in thick amorphous Si layers formed by MeV ion implantation

1990 ◽  
Vol 57 (13) ◽  
pp. 1340-1342 ◽  
Author(s):  
J. A. Roth ◽  
G. L. Olson ◽  
D. C. Jacobson ◽  
J. M. Poate
Keyword(s):  
Ion Implantation ◽  
Solid Phase ◽  
Solid Phase Epitaxy ◽  
Amorphous Si ◽  
Kinetics Of
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