Concentration Dependence of Arsenic on Solid Phase Epitaxial Regrowth of Amorphous Silicon

1989 ◽  
Vol 157 ◽  
Author(s):  
Young-Jin Jeon ◽  
M. F. Becker ◽  
R. M. Walser
Keyword(s):  
Amorphous Silicon ◽  
Low Dose ◽  
Solid Phase ◽  
Functional Dependence ◽  
Nonlinear Function ◽  
Laser Interferometry ◽  
High Dose ◽  
Temperature Dependent ◽  
Fractional Ionization ◽  
Dose Levels

ABSTRACTIn this work we measured the functional dependence of the solid phase epitaxial (SPE) regrowth rate, V, of amorphous silicon on the concentration of implanted arsenic (n-type) impurity, NAs. The SPE regrowth rates of self-ion amorphized layers in silicon wafers with (100) substrate orientation were measured by in situ, high precision, cw laser interferometry during isothermal annealing for temperatures from 470 °C to 580 °C, and concentrations in the range 1.5×1018cm−3 ≤NAs≤3.5×1020 cm−3.In the concentration range 7×1018 cm−3≤NAs≤2.2×1019 cm3, selected from the medium dose sample, the SPE regrowth data satisfied a linear equation; V/Vi=1+NAS/Ni, where Ni(T) was fit to an Arrhenius form obtained from the temperature dependent intersections of the SPE regrowth rate data with the concentration axis and Vi(T) was the temperature dependent apparent intrinsic SPE regrowth rate at zero impurity concentration. A similar linear dependence was obtained earlier for boron (B) and phosphorus (P).However, unlike B and P, an enhancement of SPE regrowth was observed for samples implanted with As in the concentration range 3×1018 cm−3 ≤NAS≤ 1.3×1019 cm−3, selected from the low dose sample. This result indicates that arsenic implanted at low dose levels has a higher fractional ionization in amorphous silicon than either boron or phosphorus implanted at the same dose.In the high dose samples with arsenic concentrations ≤NAs 2.2×1019 cm−3, the SPE regrowth rate varied nonlinearly with NAS. The nonlinear function had a negative curvature similar to that observed previously for P.

Comparison of the Effect of Boron and Phosphorus Impurities on Solid Phase Epitaxial Regrowth of Amorphous Silicon

1989 ◽  
Vol 157 ◽  
Author(s):  
Young-Jin Jeon ◽  
M.F. Becker ◽  
R.M. Walser
Keyword(s):  
Amorphous Silicon ◽  
Isothermal Annealing ◽  
Solid Phase ◽  
Laser Interferometry ◽  
Electron Pairs ◽  
Quadratic Equations ◽  
Low Concentrations ◽  
Fractional Ionization ◽  
Reported Data

ABSTRACTThis work was concerned with comparing the relative effects of boron and phosphorus impurities on the solid phase epitaxial (SPE) regrowth rate of self-ion amorphized layers in silicon wafers with (100) orientation. We used previously reported data measured by in situ, high precision, cw laser interferometry during isothermal annealing for temperatures from 450°C to 590°C, and concentrations in the range from 7.8×1018 cm-3 to 5×l020 cm-3 for boron (NB), and from 5×l017 cm-3 to 3×1020 cm-3 for phosphorus (Np) impurities. The basis for the comparison was a recently developed model that extends the Spaepen-Turnbull model for silicon recrystallization to include ionization enhanced processes.The experimental data for bom boron and phosphorus exhibited the linear variation in regrowth rate expected for low concentrations of implanted hydrogenic impurities having a concentration-independent fractional ionization in amorphous silicon. In the linear range the relative enhanced regrowth rate produced by these impurities can be expressed as a product of their, relative fractional ionizations, and the relative amount the rate constant for reconstruction is altered by localizing an electron, or a hole, at the reconstruction site. Assuming that a localized hole and electron equally softened the potential barrier for reconstruction, the experimental results indicated that boron had an ?40 meV lower barrier to ionization in amorphous silicon than phosphorus.The variations in the SPE regrowth rates with higher concentrations of both implanted boron and phosphorus were well fit by quadratic equations, but with different curvatures (+ and - for B and P respectively). This result was interpreted to indicate that SPE regrowth was further enhanced by localized hole pairs, but retarded by localized electron pairs.

Study of Enhanced Solid Phase Epitaxy of Amorphous Silicon with Low Concentrations of Implanted Phosphorous

1988 ◽  
Vol 128 ◽  
Author(s):  
Young- Jin Jeon ◽  
Won Woo Park ◽  
M. F. Becker ◽  
Rodger. M. Walser
Keyword(s):  
Amorphous Silicon ◽  
Annealing Temperature ◽  
Solid Phase ◽  
Functional Dependence ◽  
Laser Interferometry ◽  
Low Concentrations ◽  
Fractional Increase ◽  
Relative Change ◽  
Phosphorous Concentration

ABSTRACTIn this work we measured the functional dependence of the solid phase epitaxial (SPE) regrowth of amorphous silicon on the implanted phosphorous concentration, Np. The growth rates of self-ion amorphized layers in silicon wafers with (100) substrate orientation were measured by in situ, high precision, isothermal cw laser interferometry for temperatures from 460°C to 590°C, and concentrations in the range 2x1017 cm-3<Np<4x1020 cm-3. For low impurity concentrations, the fractional increase in the intrinsic SPE growth velocity ΔV/Vi depended linearly on Np as previously established for boron. For a given impurity concentration, the relative change V/Vi decreased with increasing annealing temperature.

Ionization Enhanced Solid Phase Epitaxy of Amorphous Silicon with Aluminum Impurities

1990 ◽  
Vol 205 ◽  
Author(s):  
Young-Jin Jeon ◽  
M. F. Becker ◽  
R. M. Walser
Keyword(s):  
Amorphous Silicon ◽  
Compensation Effect ◽  
Solid Phase ◽  
Functional Dependence ◽  
Laser Interferometry ◽  
Quadratic Equation ◽  
Nonlinear Dependence ◽  
High Concentration ◽  
High Concentration Range ◽  
P Type

AbstractIn this work we measured the functional dependence of the solid phase epitaxial regrowth (SPER) of amorphous silicon on NAI, the concentration of implanted aluminum (p-type). The SPER rates of self-ion amorphized layers in silicon wafers with (100) substrate orientation were measured by in situ high precision, isothermal, cw laser interferometry for temperatures from 470 °C to 550 °C, and concentrations in the range 3×1018 cm−3 ≤NAI≤ 4.7×1020 cm−3 obtained from samples implanted with three different doses.In the concentration range 3×1018 cm−3 ≤NAI≤ 2.3×1019 cm−3, we observed a “compensation effect” in which, with increasing NAI, the SPER rate decreased below the regrowth rate in intrinsic silicon and the activation energy of SPER increased to 2.85 eV, compared to 2.72 eV for intrinsic silicon. In the range 3.3×1019 cm−3 ≤NAI≤ 5.6×1019 cm−3, the regrowth rate increased linearly with NAI as previously observed for SPER in boron, phosphorus, and arsenic implanted samples. However, due to the compensation effect, the aluminum data could not be fit to the normalized equation; V/Vi = 1 + N/Ni, as was done previously for data obtained for boron, phosphorus, and arsenic. The regrowth rate increased nonlinearly to the maximum implanted concentration of 4.7× 1020 cm−3 at which the regrowth rate was more than double the previously observed maximum rate in boron doped silicon. In the high concentration range, the SPER rate enhancement could be fit by a quadratic equation whose curvature was positive as was the case for boron. This contrasts with the negative curvature required to fit the nonlinear dependence of the SPER rate on the concentration of donor impurities such as phosphorus and arsenic.

Iridium Silicides Formation on High Doses Ge+ Implanted Si Layers

1995 ◽  
Vol 402 ◽  
Author(s):  
G. Curello ◽  
R. Gwilliam ◽  
M. Harry ◽  
R. J. Wilson ◽  
B. J. Sealy ◽  
...  
Keyword(s):  
Low Dose ◽  
Rutherford Backscattering Spectrometry ◽  
Solid Phase ◽  
Strain Relaxation ◽  
Sige Layer ◽  
Thermal Reaction ◽  
High Dose ◽  
Cross Sectional ◽  
Projected Range

AbstractIn this work iridium silicidation of high dose Ge+ implanted Si layers has been studied. Compositional graded SiGe layers with a Ge peak concentration between 6 at.% and 12 at.% have been fabricated using 200 keV Ge+ ion implantation into (100) Si. A 20 nm thick Ir film was then deposited by e-beam evaporation with thermal reaction being performed to both regrow the implantation damage and form the silicide. The crystal quality of the SiGe layer and its interaction with the Ir film have been studied by cross-sectional Transmission Electron Microscopy (XTEM) and Rutherford Backscattering Spectrometry (RBS).Solid Phase Epitaxial Growth (SPEG) in the low dose case has produced a defect free SiGe layer with the formation of the IrSi phase. The annealing ambient was found to be critical for the silicidation. For the high dose case, as expected, strain relaxation related defects were observed to nucleate at a depth close to the projected range of the Ge+ implant and to extend up to the surface. A second rapid thermal annealing at higher temperatures, performed in forming gas, consumed most of the defective layer moving the silicide interface closer to the peak of the Ge distribution. A second low dose Ge+ implant following the metal deposition has been found to have a beneficial effect on the quality of the final interface. An amorphizing 500 keV Si+ implant followed by SPEG has finally been used to move the end of range defects far from the interface.

Surface phenomena related to applications regarding optimum dosages of casein superplasticizer in self-leveling underlayment cements

2019 ◽  
Vol 74 (7-8) ◽  
pp. 607-611 ◽  
Author(s):  
Hang Bian ◽  
Johann Plank
Keyword(s):  
Zeta Potential ◽  
Low Dose ◽  
Pore Solution ◽  
Time Span ◽  
High Dose ◽  
Surface Phenomena ◽  
Adsorption State ◽  
Test Flow ◽  
Dispersive Power ◽  
Dose Levels

AbstractWe experimentally investigated the optimum dosage of casein superplasticizer (SP) in self-leveling underlayments (SLUs). The undersaturated adsorption state of casein in cement pore solution was characterized by zeta potential measurements. Different amounts of casein were dosed in SLU pastes and their dispersion performance was investigated by a mini slump test. Flow values of the SLU pastes were found to increase with casein dosage, but an obvious segregation of the pastes was observed at high dose levels of SP. At an SP dosage of 0.12 wt.% bwob (by weight of binder), a homogeneous SLU paste with a spread flow of >15 cm over a time span of 30 min was obtained, which was identified as the optimum casein dosage for SLUs. Casein was found to adsorb significantly onto the surface of cement, thus producing strong dispersive power at low dose levels.

scholarly journals Sensitivity of Trypanosome Isolates From Pigs In Enugu North Senatorial Zone of Enugu State To Diminazene Aceturate And Isometamidium Chloride

2018 ◽  
Vol 1 (2) ◽  
pp. 152-160
Author(s):  
J.N Omeje ◽  
J.S Akinbobols
Keyword(s):  
Drug Resistance ◽  
Body Weight ◽  
Low Dose ◽  
Multiple Drug Resistance ◽  
Multiple Drug ◽  
High Dose ◽  
Diminazene Aceturate ◽  
Treatment Methods ◽  
Enugu State ◽  
Dose Levels

The sensitivity of trypanosome isolates from naturally infected pigs in Enugu North Senatorial Zone was evaluated in mice at two dose levels each of diminazene aceturate (7 and 28 mg/kg body weight) and isometamidium chloride (0.25 and 2 mg/kg) using the infection and treatment methods. Multiple drug resistance was prevalent in the trypanosome isolates, as all 18 isolates (16 T. brucei and 2 T. congolense) tested were resistant to both diminazene aceturate (7 mg/kg b.w) and isometamidium chloride (0.25 mg/ kg b.w,), at the low dose levels tested. Sixteen of the isolates resisted the high dose levels of diminazene aceturate (28 mg/kg b.w), while six isolates were resistant to isometamidium chloride (2 mg/kg b.w). It was concluded that trypanosome isolates from pigs in the study area exhibited resistance to both diminazene aceturate and isometamidium chloride, the two most commonly used trypanocides in the area. This phenomenon constitutes serious threat to chemotherapeutic control of swine trypanosomosis in particular and animal trypanosomosis in general in Enugu North Senatorial Zone.

Kinetics and Mechanisms of Solid Phase Epitaxy and Competitive Processes in Silicon

1984 ◽  
Vol 35 ◽  
Author(s):  
G.L. Olson
Keyword(s):  
Amorphous Silicon ◽  
Epitaxial Growth ◽  
Recent Progress ◽  
Solid Phase ◽  
Solid Phase Epitaxy ◽  
Temperature Dependent ◽  
Solid Phase Crystallization ◽  
Induced Changes ◽  
Kinetics Of ◽  
Very High

ABSTRACTRecent progress in studies of temperature dependent kinetic competition during solid phase crystallization of silicon is reviewed. Specific areas which are emphasized include: the enhancement of solid phase epitaxial growth rates by impurity-induced changes in electronic properties at the crystal/amorphous interface, the influence of impurity diffusion and precipitation in amorphous silicon on the kinetics of epitaxial growth, the effects of impurities on the kinetic competition between solid phase epitaxy and random crystallization, and the kinetics of solid phase crystallization at very high temperatures in silicon.

scholarly journals Protection of mice by living Vi and O vaccines against death caused by Salmonella paratyphi C

1957 ◽  
Vol 55 (4) ◽  
pp. 513-526 ◽  
Author(s):  
G. T. L. Archer ◽  
J. L. Whitby
Keyword(s):  
Low Dose ◽  
Positive Culture ◽  
Acute Intoxication ◽  
High Dose ◽  
Single Experiment ◽  
Series Of Experiments ◽  
Set Up ◽  
True Infection ◽  
Relationship Of ◽  
Dose Levels

In seeking a more satisfactory test than the conventional mouse-protection tests for the assessment of typhoid-paratyphoid vaccines in relation to their O and Vi antigens, it was decided to undertake a series of experiments with vaccines containing the somatic antigens of Salmonella paratyphi C and to use this organism to challenge mice thus immunized. Salm. paratyphi C contains the same Vi antigen as Salm. typhi and moreover it is capable of giving rise to a true infection in mice in contrast to the acute intoxication which follows a fatal dose of Salm. typhi.Large doses, of the order of 100 × 106, of this paratyphoid organism injected intraperitoneally into mice resulted in acute intoxication with death in 24–72 hr., similar in every way to the picture with typhoid bacilli, but when the dose was reduced 100-fold or more an infective illness was set up which after an interval of 5–10 days or more, during which the organisms multiply freely in the tissues, terminated fatally. Typhoid bacilli do not produce a true infection in mice.Living vaccines were prepared of Salm. typhi Ty6S (an almost pure Vi strain) and Salm. cholerae-suis (contains the same O-antigen complex as Salm.paratyphi C). These were used separately, and in combination, to immunize different batches of mice by the subcutaneous route against a subsequent intraperitoneal challenge with a Vi-positive culture of Salm. paratyphi C at both high- and low-dose levels. The different challenge doses were to assess the relative values of the 0 and Vi components in protecting against intoxication (high dose) and infection (low dose), respectively.Against intoxication pure Vi vaccines were almost as effective as Vi + O vaccines, whereas pure O vaccines gave little or no protection.Against fatal infection the combined Vi + O vaccine offered good protection and the pure O vaccine was but little inferior, whereas the pure Vi vaccine appeared to be without significant effect.Quite small doses of Salm. paratyphi C administered by the intra-gastric route can give rise to a general infection in mice, but in order to obtain consistent results much larger doses were found necessary (about 300 x 106 organisms). Mice immunized with the same three vaccines and subsequently challenged by the intragastric route with this large dose showed significant protection throughout. The combined, O + Vi, vaccine did not appear to have any advantage over the pure O vaccine, but both were markedly superior to the pure Vi vaccine. Further experiments on the same lines are however necessary to see if the results obtained in this single experiment are reproducible.The relationship of the above findings to the evaluation of agents employed in man for the prophylaxis of enteric fever and the need for further experimental work of a similar nature are discussed.We wish to thank Dr F. Kauffmann for strains of Salm. paratyphi C, Lt-Col. T. E. Field, whose results we have freely quoted, and Dr S. Peto for advice on statistical evaluation of our results.

SOME EFFECTS OF MAMMALIAN THYROID STIMULATING HORMONE, ELASMOBRANCH PITUITARY GLAND EXTRACTS AND TEMPERATURE ON THYROIDAL ACTIVITY IN NEWLY HATCHED DOGFISH (SCYLIORHINUS CANICULUS)

1961 ◽  
Vol 22 (4) ◽  
pp. 395-NP ◽  
Author(s):  
J. N. DENT ◽  
J. M. DODD
Keyword(s):  
Pituitary Gland ◽  
Low Dose ◽  
Thyroid Stimulating Hormone ◽  
Adult Brain ◽  
Effect Of Temperature ◽  
High Dose ◽  
Aqueous Extracts ◽  
Iodine Metabolism ◽  
Dose Levels ◽  
Stimulating Hormone

SUMMARY 1. Groups of recently hatched dogfish (Scyliorhinus caniculus) were given a series of injections of mammalian thyroid stimulating hormone (TSH) at three dose levels, or of aqueous extracts of each of the three lobes of the adult elasmobranch pituitary gland. Control animals received injections of distilled water or extract of adult brain. The uptake of 131I by the thyroid was measured subsequent to the injections and the histology of the thyroid was studied. The experiments were conducted over a range of temperatures, thus producing data on the effect of temperature variation on thyroidal activity. 2. The uptake of 131I by the thyroid gland is very markedly enhanced by a high dose of mammalian TSH (1·00 i.u.) and is significantly increased by an intermediate dose (0·10 i.u. TSH). Enhancement by a very low dose (0·01 i.u. TSH) is doubtful, the observed increase in uptake of 131I being significant only at the 10% level. The highest dose also accelerated folliculogenesis and induced hyperplastic changes in the thyroid. 3. There were indications that the extract of the ventral lobe of the adult elasmobranch pituitary contains a thyroid-stimulating principle. 4. The rate of iodine metabolism increases directly with the temperature over the range 8·6–13·6° C.

The Nature of Electrically Inactive Implanted Arsenic in Silicon after Rapid Thermal Annealing

1991 ◽  
Vol 224 ◽  
Author(s):  
John L. Altrip ◽  
Alan G.R. Evans ◽  
Nigel D. Young ◽  
John R. Logan
Keyword(s):  
Hall Effect ◽  
Thermal Annealing ◽  
Rapid Thermal Annealing ◽  
Room Temperature ◽  
Low Dose ◽  
Solubility Limit ◽  
High Dose ◽  
Temperature Dependent ◽  
Spreading Resistance ◽  
Hall Effect Measurements

AbstractThe electrical activation of As implanted Si has been investigated on rapid thermal annealing timescales using sheet resistance, spreading resistance and Hall Effect techniques. For high dose implants (>1015 As cm-2) differential Hall Effect and spreading resistance profiles confirm the existence of a temperature dependent electrical solubility limit. However for low dose implants, annealing schedules chosen such that the electrical solubility limit is not exceeded reveal electrical deactivation which is not accounted for in the clustering theory. Hall Effect measurements performed as a function of temperature have enabled us to reveal directly electrically inactive As which is not observable at room temperature using standard electrical techniques. The results indicate that As atoms in Si introduce deep trapping levels within the bandgap which are responsible forremoving As from the conduction process at room temperature. This temperature activated process is characterized with an activation energy of 0.4eV.

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