The Influence of Implantation-Induced Non-Stoichionetry on the Epitaxial Recrystallization of CoSi2

1993 ◽  
Vol 320 ◽  
Author(s):  
M.C. Ridgway ◽  
A. Vantomme ◽  
A.-M. Van Bavel ◽  
G. Langouche
Keyword(s):  
Phase Separation ◽  
Defect Formation ◽  
Rutherford Backscattering Spectrometry ◽  
Solid Phase ◽  
Rate Reduction ◽  
Dose Ratio ◽  
Time Resolved ◽  
Si Substrates ◽  
Rate Retardation ◽  
Si Ion Implantation

ABSTRACTEpitaxial CoSi2 layers on Si substrates have been amorphized with Co and/or Si ion implantation. The influence of nonstoichiometry on the rate of solid-phase epitaxial growth (SPEG) of amorphized CoSi2 has been investigated with time-resolved reflectivity, Rutherford backscattering spectrometry and Mossbauer spectrometry, the latter with radioactive 57Co probes. A decrease in SPEG rate was apparent with an increase in nonstoichiometry. For a given ion dose, the decrease was greater following Co implantation. The means by which non-stoichiometry is accommodated in a crystalline CoSi2 lattice - either through phase separation or defect formation - has been considered. SPEG rate retardation was also evident in samples implanted with both Si and Co ions with a Si:Co dose ratio of 2:1. Additional mechanisms may thus also contribute to the observed SPEG rate reduction.

Low-Temperature, Solid-Phase Epitaxial Growth of Amorphized, Non-Stoichiometric GaAs

1995 ◽  
Vol 378 ◽  
Author(s):  
K. B. Belay ◽  
D. L. Llewellyn ◽  
M. C. Ridgway
Keyword(s):  
Low Temperature ◽  
Epitaxial Growth ◽  
Rutherford Backscattering Spectrometry ◽  
Solid Phase ◽  
Present Report ◽  
Time Resolved ◽  
Crystalline Layer ◽  
Transmission Electron ◽  
High Doses ◽  
Insulating Properties

AbstractNon-stoichiometric GaAs layers with semi-insulating properties can be produced by low-temperature molecular beam epitaxy or ion implantation. The latter is the subject of the present report wherein the solid-phase epitaxial growth of amorphized, non-stoichiometric GaAs layers has been investigated with time-resolved reflectivity, Rutherford backscattering spectrometry and transmission electron microscopy. GaAs substrates were implanted with Ga and/or As ions and annealed in air at a temperature of 260°C. The recrystallized material was composed of a thin, crystalline layer bordered by a thick, twinned layer. Non-stoichiometry results in a roughening of the amorphous/crystalline interface and the transformation from planar to non-planar regrowth. The onset of the transformation and the rate thereof can increase with an increase in non-stoichiometry. Non-stoichiometry can be achieved on a macroscopic scale via Ga or As implants or on a microscopic scale via Ga and As implants. The influence of the latter is greatest at low doses whilst the former dominates at high doses.

Influence of Hydrogen On The Solid Phase Epitaxial Regrowth of Strained Layer Silicon Germanium Alloys

1995 ◽  
Vol 379 ◽  
Author(s):  
D. Love ◽  
D. Endisch ◽  
T.W. Simpson ◽  
T.D. Lowes ◽  
I.V. Mitchell ◽  
...  
Keyword(s):  
Silicon Germanium ◽  
Rutherford Backscattering Spectrometry ◽  
Solid Phase ◽  
Ion Irradiation ◽  
Amorphous Region ◽  
Elastic Recoil ◽  
Double Crystal ◽  
Time Resolved ◽  
Strained Layer ◽  
Detection Analysis

ABSTRACTStrained layer Si/Si0.79Ge0.21 superlattices consisting of 16 alternating 19.0 nm Si0.79Ge0.21 / 18.5 nm Si layers have been amorphized by Si ion irradiation, then implanted with H ions to nominal atomic concentrations of 1%, 0.1% and 0.05% within the amorphized region. Subsequent solid phase epitaxy (SPE) at a regrowth temperature of 575°C was monitored in situ by time resolved reflectivity (TRR) measurements, while changes in the H distribution were measured by elastic recoil detection analysis (ERDA). Analysis was supplemented by Rutherford backscattering spectrometry (RBS), x-ray double crystal diffraction and reflectivity (DCD/XRF) and transmission electron microscopy (TEM). TRR data reveals a decrease in the initial SPE rate in the Si substrate from 4.9 Å/sec (no H) to 2Å/sec for 1% H concentration as well as a rate decrease as the interface enters the Si/SiGe layers. TRR also indicates an increased roughness in the crystal/amorphous interface with increasing H concentration. ERDA reveals that a significant fraction of the implanted H is stable in the amorphous region for the anneal times (10-30 min) at 575°C, while in the regrown lattice the H concentration has dropped below 20 ppm, near the detection limit of the ERDA. DCD shows almost no strain in the regrown structures. TEM and RBS channeling techniques reveal degradation in the crystal quality of epitaxially regrown structures and a large concentration of strain relieving defects originating near the second deepest of eight SiGe layers in all regrown structures. XRF indicates decreasing sharpness of the regrown Si/SiGe interfaces with increasing H concentration.

Crystallization Kinetics of Fe-DOPED A1203

1994 ◽  
Vol 357 ◽  
Author(s):  
Todd W. Simpson ◽  
Ian V. Mitchell ◽  
Ning Yu ◽  
Michael Nastasi ◽  
Paul C. Mcintyre
Keyword(s):  
Crystallization Kinetics ◽  
Annealing Temperature ◽  
Rutherford Backscattering Spectrometry ◽  
Solid Phase ◽  
Solid Phase Epitaxy ◽  
Time Resolved ◽  
Α Phase ◽  
Kinetics Of ◽  
Beam Deposition

AbstractTime resolved optical reflectivity (TRR) and Rutherford backscattering spectrometry (RBS) and ion channelling methods have been applied to determine the crystallization kinetics of Fe-doped A1203 in the temperature range of 900-1050°C. Amorphous A1203 films, approximately 250 nm thick and with Fe cation concentrations of 0, 1.85, 2.2 and 4.5%, were formed by e-beam deposition on single crystal, [0001] oriented, A1203 substrates. Annealing was performed under an oxygen ambient in a conventional tube furnace, and the optical changes which accompany crystallization were monitored, in situ, by TRR with a 633nm wavelength laser.Crystallization is observed to proceed via solid phase epitaxy. An intermediate, epitaxial phase of -γ-Al203 is formed before the samples reach the ultimate annealing temperature. The 5% Fe-doped film transforms from γ to α-A1203 at a rate approximately 10 times that of the pure A1203 film and the 1.85% and 2.2% Fe-doped films transform at rates between these two extremes. The Fe-dopants occupy substitional lattice sites in the epilayer. Each of the four sets of specimens displays an activation energy in the range 5.0±0.2eV for the γ,α phase transition.

Time-resolved immunofluorometric assay of 34-kDa somatomedin-binding protein.

1987 ◽  
Vol 33 (7) ◽  
pp. 1126-1128 ◽  
Author(s):  
R Koistinen ◽  
U H Stenman ◽  
H Alfthan ◽  
M Seppälä
Keyword(s):  
Phase Separation ◽  
Detection Limit ◽  
Solid Phase ◽  
Polyclonal Antibodies ◽  
Binding Protein ◽  
Time Resolved

Abstract In this time-resolved immunofluorometric assay for the 34-kDa somatomedin-binding protein (SmBP), affinity-purified polyclonal antibodies are used, along with solid-phase separation of bound and free analyte. The first antibody is bound to polystyrene microtiter wells; the second is labeled with europium(III) chelate. The detection limit of the method is 0.25 microgram/L, much lower than that (about 8 micrograms/L) for radioimmunoassay. By immunofluorometric assay, SmBP is detectable, and could be accurately quantified, in the serum of all 88 individuals we tested, whereas by radioimmunoassay a third of the samples had concentrations below the detection limit. When SmBP was detectable by both methods, the concentrations measured by the two techniques correlated well (r = 0.98).

Effect of Biaxial Stress on Solid Phase Epitaxy of Silicon

1992 ◽  
Vol 263 ◽  
Author(s):  
Guo-Quan Lu ◽  
Tapan K. Gupta
Keyword(s):  
Growth Kinetics ◽  
Growth Rates ◽  
Solid Phase ◽  
Biaxial Stress ◽  
Optical Measurements ◽  
Back Side ◽  
Time Resolved ◽  
Tensile Stresses ◽  
Rate Retardation ◽  
Amorphous Surface

ABSTRACTThe effect of biaxial stress on solid phase epitaxial growth (SPEG) rate of crystalline Si(100) into self-implanted amorphous surface layer has been measured. Biaxial stresses in the crystalline and amorphous phases were generated by bending the silicon wafer using the residual stresses in Ge films deposited on the back side of the wafer. Stresses were determined at SPEG temperatures by optical measurements of wafer bending curvatures. Tensile stresses up to 13 MPa in the crystalline phase and 34 MPa in the amorphous phasewere achieved during SPEG at 530ºC. An optical system based on the time-resolved reflectivity (TRR) technique was devised to measure the growth rates of two adjacent samples during a single SPEG run. This enables a direct comparison of the growth rates under different stress conditions without concern for run-to-run temperature variations. We found that the growth kinetics in all the samples were retarded as the c/a interface approached the free surface. However, the extent of this rateretardation was reducedin the stressed samples, leading to stress-enhanced growth kinetics. We speculate that the application of the biaxial tensile stresses might slow down the incorporation of hydrogen into the amorphous phase, a mechanism for the rate-retardation.

The Effects of Rapid Recrystallization and Ion Implanted Carbon on The Solid Phase Epitaxial Regrowth of Si1−xGex Alloy Layers On Silicon

1995 ◽  
Vol 379 ◽  
Author(s):  
M.J. Antonell ◽  
T.E. Haynes ◽  
K.S. Jones
Keyword(s):  
Elevated Temperatures ◽  
Defect Formation ◽  
Solid Phase ◽  
Growth Front ◽  
Threading Dislocation ◽  
Time Resolved ◽  
Ion Channeling ◽  
Epitaxial Regrowth ◽  
Transmission Electron ◽  
Threading Dislocation Density

ABSTRACTTransmission electron microscopy has been combined with time-resolved reflectivity and ion channeling to study the effects of regrowth temperature and carbon introduction by ion implantation on the solid phase epitaxial regrowth (SPER) of strained 2000Å, Sio.88Ge0.12/Si alloy films grown by molecular-beam epitaxy (MBE). Relative to the undoped layers, carbon incorporation in the MBE grown SiGe layers prior to regrowth at moderate temperatures (500- 700°C) has three main effects on SPER; these include a reduction in SPER rate, a delay in the onset of strain-relieving defect formation, and a sharpening of the amorphous-crystalline (a/c) interface, i.e., promotion of a two-dimensional (planar) growth front.1 Recrystallization of amorphized SiGe layers at higher temperatures (1 100°C) substantially modifies the defect structure in samples both with and without carbon. At these elevated temperatures threading dislocations extend completely to the Si/SiGe interface. Stacking faults are eliminated in the high temperature regrowth, and the threading dislocation density is slightly higher with carbon implantation.

Interface Stability During Solid Phase Epitaxy Of Strained GexS1-x Films on Si (100)

1993 ◽  
Vol 321 ◽  
Author(s):  
Xiaobiao Zeng ◽  
Tan-Chen Lee ◽  
John Silcox ◽  
Michael O. Thompson
Keyword(s):  
Ion Implantation ◽  
Solid Phase ◽  
Interface Roughness ◽  
Final Thickness ◽  
Time Resolved ◽  
Transmission Electron ◽  
Interface Roughening ◽  
20 Nm ◽  
Anneal Temperature ◽  
Si Ion Implantation

ABSTRACTStrained solid phase epitaxial (SPE) regrowth of amorphous GexSi1-x on Si (100) substrates was studied using time-resolved reflectivity (TRR). Films of CVD-grown Ge0.13Si0.87 on Si were amorphized by Si ion implantation, and subsequently regrown at temperatures between 550°C and 610°. Information on regrowth dynamics and interface roughness evolution was obtained by accurately modeling the complicated TRR data for GexSi1-x regrowth using a Moving, statistically roughening interface. The SPE regrowth rate slowed as the interface crossed into the GexSi1-x layer and the originally planar interface roughened, as confirmed by transmission electron Microscopy. A Minimum in the regrowth velocity was observed after regrowing approximately 60 nm into the GexSi1-x layer; the SPE rate subsequently increased to a final, thickness-dependent velocity that was still below that for pure Si. Upon entering the GexSi1-x layer, the interface roughened quickly to a 15–20 nm amplitude, increasing only slightly more during the remainder of regrowth. The degree of roughening and velocity reduction was found to be dependent on the anneal temperature. In contrast, samples with low Ge concentrations (< 3 at.%) prepared by ion implantation exhibited minimal interface roughening and essentially identical SPE velocities as pure Si.

A Time-Resolved Low-Angle Light Scattering Apparatus. Application to Phase Separation Problems in Polymer Systems

2001 ◽  
Vol 66 (6) ◽  
pp. 973-982 ◽  
Author(s):  
Čestmír Koňák ◽  
Jaroslav Holoubek ◽  
Petr Štěpánek
Keyword(s):  
Phase Separation ◽  
Light Scattering ◽  
Signal To Noise Ratio ◽  
Scattered Light ◽  
Ccd Camera ◽  
Time Resolved ◽  
Polymer Systems ◽  
Software Analysis ◽  
Phase Separation Kinetics ◽  
Small Angle Light Scattering

A time-resolved small-angle light scattering apparatus equipped with azimuthal integration by means of a conical lens or software analysis of scattering patterns detected with a CCD camera was developed. Averaging allows a significant reduction of the signal-to-noise ratio of scattered light and makes this technique suitable for investigation of phase separation kinetics. Examples of applications to time evolution of phase separation in concentrated statistical copolymer solutions and dissolution of phase-separated domains in polymer blends are given.

scholarly journals Prion-Like Proteins in Phase Separation and Their Link to Disease

Biomolecules ◽  
2021 ◽  
Vol 11 (7) ◽  
pp. 1014
Author(s):  
Macy L. Sprunger ◽  
Meredith E. Jackrel
Keyword(s):  
Protein Folding ◽  
Phase Transitions ◽  
Phase Separation ◽  
Liquid Phase ◽  
Protein Misfolding ◽  
Solid Phase ◽  
Liquid Phase Separation ◽  
Therapeutic Approaches ◽  
Important Physiological Process ◽  
Liquid Liquid Phase Separation

Aberrant protein folding underpins many neurodegenerative diseases as well as certain myopathies and cancers. Protein misfolding can be driven by the presence of distinctive prion and prion-like regions within certain proteins. These prion and prion-like regions have also been found to drive liquid-liquid phase separation. Liquid-liquid phase separation is thought to be an important physiological process, but one that is prone to malfunction. Thus, aberrant liquid-to-solid phase transitions may drive protein aggregation and fibrillization, which could give rise to pathological inclusions. Here, we review prions and prion-like proteins, their roles in phase separation and disease, as well as potential therapeutic approaches to counter aberrant phase transitions.

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