Presence Of Fringes Research Articles

Low Temperature Selective Epitaxy of Group-IV Semiconductors for Nanoelectronics

Continuous improvement of device performance is becoming very challenging as the transistor dimension approaches the physical limits of scalability. In particular, the source/drain (S/D) layer resistivity and contact resistance at the S/D region became major components for further parasitic resistance reduction [1]. Therefore, layers with high active doping concertation is required for future technology nodes. From another side, novel architectures such as 3D-stacked devices constraints the allowed thermal budget for epitaxy processes [2]. In this work, we will review our recent achievements on LT epitaxy for both Si:P and SiGe:B layers to enable (i) parasitic resistance reduction and (ii) novel integration schemes.All layers were grown in a 300 mm ASM reduced pressure chemical vapor deposition reactor on Si(001) substrates and patterned substrates.Firstly, we will discuss the benefits of SiP growth at low temperature leading to high active doping concentrations (~1.1×1021 cm-3), as reported in our previous work [3]. Figure 1 shows the omega-2theta scans around the symmetric (004) reflections of the Si:P/Si stacks. As expected, reducing the Si precursor flow leads to a higher substitutional P (~7.5%) incorporation in the layer. The good crystallinity of the SiP layer is attested by the well-defined thickness fringes. Figure 2a represents the XRR scans of non-selective SiP process and selective SiP process compared to 100 nm bare SiO2 on Si substrate. The presence of fringes (red curve) indicates that a 2D amorphous SiP layer is deposited on SiO2. To confirm the full selectivity of the process and the absence of nuclei on the SiO2 surface, top view SEM was performed (cf. Figure 2b).Afterwards, we will focus on the SiGe:B epitaxy at low temperature. Figure 3a shows omega-2theta scans around the symmetric (004) reflections of the SiGe:B/Si stacks for various B flows. The apparent Ge content drops from 52.1% to around 41.3% when B flow was multiplied by 16. The inset represents the reciprocal space map (RSM) around the asymmetric (224) peak of SiGe:B layers grown on Si(001) substrates with the highest B flow. The RSM clearly indicates high quality and fully strained SiGe:B layer. Figure 3b depicts the apparent Ge drop vs B flow. This reduction in Ge content is attributed to B strain compensation effect leading to artificially lower Ge content [4]. Figure 3c represents SiGe:B layer resistivity vs B flow. Resistivity drops until a critical B flow and then increases with increasing B flow. Figure 4 shows active doping concentration and Hall mobility as function of the B flow. The Hall measurements were performed on a cleaved wafer edge and assume a Hall scattering factor of 1. Active carrier concertation increases with increased B flow. As a side effect of the higher activation, the Hall mobility is lowered likely due to an increase in ionized impurity scattering which is the reason why the resistivity does not decrease substantially below a certain value for higher B flows at current growth conditions. Layers with similar physical properties have resulted in S/D metal contact resistivity of ~5×10-10 Ohm.cm2 [5]. Figure 5 depicts the selective process on advanced patterned nanosheet test structures. Figure 5a illustrates the selectivity towards several nanosheet structures, Figure 5b shows a zoomed in image indicating selective process towards inner SiN spacers and SiO2. Figure 5c is a FFT of the SiGe:B area indicated by red square and Figure 5d is an EDS map of the key elements (Si, Ge, O, C, Cl, F, N). Figure 6a and 6b show the selective process stability over 20 runs. The HR-XRD measurements at wafer center are represented in Figure 6a. Figure 6b represents the resistivity at the wafer center. Thickness uniformity across one of the wafer is illustrated in Figure 6c. The results indicate excellent wafer to wafer and within wafer uniformities despite low temperature processing.LT epitaxy offers several advantages to reach high active doping concentrations and enable novel integration schemes. Despite challenges associated to LT epitaxy, in this work we showed the possibility to grow selective layers while maintaining the excellent physical layer properties, within wafer uniformity and wafer to wafer reproducibility.[1] H. Wu et al. EEE International Electron Devices Meeting (IEDM), (2018), pp. 35.4.1.[2] A. Vandooren et al. IEEE Symposium on VLSI Technology, (2018), pp. 69-70.[3] R. Khazaka et al. ECS Meeting s, MA2020-02(24), (2020) 1734-1734.[4] J.M. Hartmann et al. ECS JSST, 3(11) (2014) 382.[5] H. Xu et al. IEEE Symposium on VLSI Technology, (2022), (to be published). Figure 1

Methodological approaches to the veterinary and sanitary examination of Acipenseriformes species

The aim of this study was to describe the methodological approaches to the peculiarities of veterinary and sanitary examination of Acipenseriformes species. Many species of this family differ in nutritional and biological value, which affects pricing. In addition, species identification prevents the sale of counterfeit and illegal (poaching) fish products. Currently, there are no available methods for accurately determining the Acipenseriformes species. 15 fishes of the sturgeon family were taken for this study. The comparative description of organoleptic, morphological, anatomical and topographic features for species identification was studied. It is necessary to develop a technique that would be applicable for quick determination of Acipenseriformes species. It is reliable to count the gill stamens, determine the number and structure of the rays of the fins and gill covers, the absence or presence of fringes on the tendrils.

Identification and characterization of hybrids of Acipenser ruthenus and Acipenser baerii (Actinopterygii, Acipenseriformes) from the Irtysh River

Two sturgeon species, Acipenser ruthenus (Linnaeus, 1758) and Acipenser baerii (Brandt, 1869), inhabit the Irtysh basin. In 2018, we received some “atypical” specimens of sturgeon, which were similar to A. ruthenus but had a number of pronounced external differences. The hybrids A. ruthenus × A. baerii, named “oster”, can sometimes be caught in natural habitats in the Ob and the Yenisei rivers. Despite the development of methods for the genetic identification of sturgeons, the molecular genetic characteristics of the hybrids of A. baerii and A. ruthenus have not been carried out. The purpose of this study is to develop a complex of morphological and genetic characters to identify the hybrid of A. ruthenus and A. baerii from the Irtysh River. We used a complex of morphological and genetic methods to compare the putative hybrids with parental species The putative hybrids were similar to A. ruthenus in the number of dorsal scutes, the number of rays in the dorsal and anal fins, the structure of stamens on the first gill arch, and the presence of fringe on the tendrils. The hybrids were similar to A. baerii in size and weight values, the structure of dorsal scutes, the number of lateral and ventral scutes, and the number of gill rakers on the first gill arch. Genotyping of putative hybrids by using the Inter Simple Sequence Repeat (ISSR) markers revealed the presence of sites characteristic of both parental species. The fragment of the control region of mitochondrial DNA in the hybrids matched to that of A. baerii that allowed us to identify females of A. baerii as maternal individuals of the hybrids. Possible causes and factors promoting interspecific hybridization of A. ruthenus and A. baerii were studied. This is the first described fact of the appearance of sturgeon hybrids in the Ob-Irtysh basin. It is necessary to continue monitoring studies to identify the number of these hybrids in the ecological system of the Irtysh River. The data set of morphological characters and genetic methods can be used to identify the hybrids of A. ruthenus and A. baerii.

Synthesis and graphitization of resole resins by ferrocene

Commercial (Rs) and laboratory synthesized resoles (LSRs) containing 3–5 wt% ferrocene have been used to study the development of thermosetting resin compositions as binder materials for carbon-containing refractories (CCRs) production. The LSRs were developed based on formaldehyde to phenol 1.5 mol.% (1.5Rs) and 2.0 mol.% (2Rs). Microstructure and oxidation resistance of carbons derived from plain and modified resins have been compared. Chemical structure of the resins was studied using Fourier Transform InfraRed-Attenuated Total Reflection (FTIR-ATR) spectroscopy. X-ray Photoelectron spectroscopy was used to examine chemical changes during heat treatment of the modified products. Flow behavior of plain and formulated resins has been measured under isothermal condition. Rheology measurement results show that the selected amount of ferrocene did not affect the resin near-Newtonian fluid behavior and processability during refractory production. X-ray diffraction (XRD) analysis and transmission Electron Microscope (TEM) were used to characterize the derived carbon samples after thermal treatment of the resins. The results demonstrate that ferrocene is an excellent additive for crystallizing resoles carbon. The presence of fringes in TEM images indicates the graphitized carbon microstructure. The carbon reactivity in an oxidizing environment was also determined via thermogravimetric analyzer (TGA). Several factors, such as bond strength and atoms arrangement, have been found to control the carbonized modified-resin oxidation resistance.

2D melting of confined colloids with a mixture of square and triangular order

We implement Brownian dynamics to investigate the melting processes of colloidal particles confined isotropically and interacting via a potential which can be tailored in a repulsive–attractive–respulsive fashion as the interparticle distance increases. The stable configurations of such a system is composed of a large diversity of structures, which includes quasicrystalline, triangular, square, and mixed orderings, as well as the presence of fringes and holes, which are located, respectively, at the border and interior of the clusters. Our simulations demonstrate that during the melting process particles are able to swing between different micro phases. This intermediary stage, present in a finite range of temperature, precedes the melting in all cases investigated and is different from the hexatic phase of the KTNHY framework. We also test the fringes stability and find it to be higher than the one found in compact clusters. Finally, we show that, at the high temperature regime, the system loses its angular ordering while still preserves its radial interparticle confinement, which, ultimately, causes the proliferation of small subclusters.

Mapping Pluto’s Republic

The presence of fringe and debatable methods and theories is widespread in the academia, excluding practically no discipline. Since theoretical reliability, epistemic warrant and empirical support are contentious issues, the demarcation between science and pseudoscience remains highly controversial, especially in the Humanities. However, a renewed interest in the demarcation problem holds much promise to tackle the underlying methodological and epistemological questions. This review essay briefly deals with the historiographical resilience of pseudoscience and the fascination which psi phenomena in the academic history of religion in the light of Massimo Pigliucci and Maarten Boudry’s recently co-edited book, entitled Philosophy of Pseudoscience: Reconsidering the Demarcation Problem (Chicago, IL: The University of Chicago Press, 2013). A detailed review of Pigliucci and Boudry’s volume is also provided.

Two new species of Glyphocrangon (Decapoda: Caridea: Glyphocrangonidae) from the East China Sea and the Philippines.

The present paper reports two new species of Glyphocrangon (Crustacea, Caridea, Glyphocrangonidae) collected respectively from the East China Sea and the Philippines. G. singularis sp. nov., from the East China Sea, is similar to G. fimbriata Komai & Takeuchi, 1994 with the presence of fringe of setae on dactyl of the third to fifth pereopods, but differs from G. fimbriata by the rostrum shape and the armature on the carapace; G. denticulata sp. nov., from the Philippines, is similar to G. pugnax De Man, 1918 with the entire anterior third carina, but differs from G. pugnax by armatures of the antennal scaphocerite and carapace, the lengths of rostrum and the spines of fifth abdominal somite, and the colouration of carapace.

Fringe-mediated extension of O-linked fucose in the ligand-binding region of Notch1 increases binding to mammalian Notch ligands.

The Notch signaling pathway is essential for many aspects of development, cell fate determination, and tissue homeostasis. Notch signaling can be modulated by posttranslational modifications to the Notch receptor, which are known to alter both ligand binding and receptor activation. We have modified the ligand-binding region (EGF domains 11-13) of human Notch1 (hN1) with O-fucose and O-glucose glycans and shown by flow cytometry and surface plasmon resonance that the Fringe-catalyzed addition of GlcNAc to the O-fucose at T466 in EGF12 substantially increases binding to Jagged1 and Delta-like 1 (DLL1) ligands. We have subsequently determined the crystal structures of EGF domains 11-13 of hN1 modified with either the O-fucose monosaccharide or the GlcNAc-fucose disaccharide at T466 of EGF12 and observed no change in backbone structure for each variant. Collectively, these data demonstrate a role for GlcNAc in modulating the ligand-binding site in hN1 EGF12, resulting in an increased affinity of this region for ligands Jagged1 and DLL1. We propose that this finding explains the Fringe-catalyzed enhancement of Notch-Delta signaling observed in flies and humans, but suggest that the inhibitory effect of Fringe on Jagged/Serrate mediated signaling involves other regions of Notch.

A new species of four-eyed frog genus Pleurodema Tschudi, 1838 (Anura: Leiuperidae) from the rock meadows of Espinhaço range, Brazil

A new Brazilian species of Pleurodema, closer to Pleurodema diplolister (Peters), from the Brazilian rock meadows (Campos Rupestres) is described. This new species is characterized by the following combination of traits: medium size (males 32.3–36.1 mm SVL); lumbar gland absent; tarsal fold absent; presence of a tarsal tubercle near the heel; inner metacarpal tubercle rounded and well developed in males; supernumerary tubercles on hand absent or vestigial; annulus tympanicus distinct; absence or vestigial presence of fringes in fingers; and absence of flash coloration in the hidden portions of the thighs and groin.

In Vitro Reconstitution of the Modulation of Drosophila Notch-Ligand Binding by Fringe

Notch signaling plays critical roles in animal development and physiology. The activation of Notch receptors by their ligands is modulated by Fringe-dependent glycosylation. Fringe catalyzes the addition of N-acetylglucosamine in a beta1,3 linkage onto O-fucose on epidermal growth factor-like domains. This modification of Notch by Fringe influences the binding of Notch ligands to Notch receptors. However, prior studies have relied on in vivo glycosylation, leaving unresolved the question of whether addition of N-acetylglucosamine is sufficient to modulate Notch-ligand interactions on its own, or whether instead it serves as a precursor to subsequent post-translational modifications. Here, we describe the results of in vitro assays using purified components of the Drosophila Notch signaling pathway. In vitro glycosylation and ligand binding studies establish that the addition of N-acetylglucosamine onto O-fucose in vitro is sufficient both to enhance Notch binding to the Delta ligand and to inhibit Notch binding to the Serrate ligand. Further elongation by galactose does not detectably influence Notch-ligand binding in vitro. Consistent with these observations, carbohydrate compositional analysis and mass spectrometry on Notch isolated from cells identified only N-acetylglucosamine added onto Notch in the presence of Fringe. These observations argue against models in which Fringe-dependent glycosylation modulates Notch signaling by acting as a precursor to subsequent modifications and instead establish the simple addition of N-acetylglucosamine as a basis for the effects of Fringe on Drosophila Notch-ligand binding.

A new species of Colostethus (Anura: Dendrobatidae) with maternal care from Kaieteur National Park, Guyana

A new species of Colostethus is described from Kaieteur National Park, Guyana, South America. The new species can be distinguished from close relatives by the presence of a median lingual process, first finger equal to second, Finger III not distinctly swollen but all fingers slightly swollen in males, presence of fringes on fingers, presence of a dorsolateral stripe from posterior corner of eye, absence of an oblique lateral stripe, and differences in tadpole morphology, colouration and pattern, vocalizations and ecology. This is only the second species of Colostethus known to provide maternal care for tadpoles.

Bending Contours in Silver Nanoprisms

A detailed electron microscopy analysis is reported on the structure of silver nanoprisms synthesized by controlled photoinduced aggregation of Ag nanoparticles. Bending of the nanoprism (111) face is directly revealed in the presence of fringes in both bright and dark field TEM images, which are unequivocally assigned to bending contours. Such contours can be individually imaged through shifting of the objective aperture and selectively allowing transmission of the corresponding diffraction spot. The assignment of a bent structure is supported by images of the lateral sides of the prisms, and high-resolution images where apparent changes in the lattice constant are observed.

An O-fucose site in the ligand binding domain inhibits Notch activation.

Two glycosyltransferases that transfer sugars to EGF domains, OFUT1 and Fringe, regulate Notch signaling. However, sites of O-fucosylation on Notch that influence Notch activation have not been previously identified. Moreover, the influences of OFUT1 and Fringe on Notch activation can be positive or negative, depending on their levels of expression and on whether Delta or Serrate is signaling to Notch. Here, we describe the consequences of eliminating individual, highly conserved sites of O-fucose attachment to Notch. Our results indicate that glycosylation of an EGF domain proposed to be essential for ligand binding, EGF12, is crucial to the inhibition of Serrate-to-Notch signaling by Fringe. Expression of an EGF12 mutant of Notch (N-EGF12f) allows Notch activation by Serrate even in the presence of Fringe. By contrast, elimination of three other highly conserved sites of O-fucosylation does not have detectable effects. Binding assays with a soluble Notch extracellular domain fusion protein and ligand-expressing cells indicate that the NEGF12f mutation can influence Notch activation by preventing Fringe from blocking Notch-Serrate binding. The N-EGF12f mutant can substitute for endogenous Notch during embryonic neurogenesis, but not at the dorsoventral boundary of the wing. Thus, inhibition of Notch-Serrate binding by O-fucosylation of EGF12 might be needed in certain contexts to allow efficient Notch signaling.

Superposition states at finite temperature

We describe a method to create superposition states from a mixed state of a harmonic oscillator. If the initial state is described by a thermal state, then the resulting superposition state will be a ``hot'' superposition state. Such a state can be distinguished from a statistical mixture by its coherence properties. Here we suggest how to demonstrate the coherence of the superposition state by observing interference fringes when the two parts of the wave packet are overlapped. In the case of the mixed superposition state, a partial overlap may not be sufficient to observe the presence of fringes. We introduce therefore the idea of a coherence length for the wave packet and demonstrate its relevance for interferometry of mixed states. We illustrate our ideas with the example of superposition states for the motion of a single trapped ion.

Computer simulation of neutron diffraction from coupled and uncoupled magnetic superlattices (abstract)

Neutron diffraction is a powerful tool for investigating interlayer coupling phenomena in magnetic superlattices. In the absence of interlayer spin coherence the diffraction spectrum has the form of a broad smooth maximum, i.e., it essentially reproduces the shape of the single-layer structure factor. In contrast, spectra from correlated superlattices exhibit characteristic fringe patterns. However, doubts are sometimes expressed as to whether the presence of fringes indeed provides meaningful evidence for interlayer coherence; such opinions are usually based on results of computer simulations that produce “fringelike” features even though the magnetization in consecutive layers changes in a random fashion. Clarity in this issue is certainly of importance, especially in studies of systems with antiferromagnetic layers, in which neutron diffraction is practically the only experimental tool capable of detecting interlayer spin coherence. We report the results of thorough computer modeling studies that show that the “pseudofringes” obtained from simulations on uncoupled superlattice models disappear after averaging the data from a sufficiently large number of random configurations. It is a reasonable expectation that in a real superlattice each magnetic layer breaks into a large number of domains, so neutrons passing through the sample “see” different situations. Hence, realistic modeling does require averaging over many random configurations, and our results point out that in following such a procedure, the “fringelike” features eventually wash out, and the simulated spectra become fully consistent with the analytical single-layer structure factor. However, there is still the possibility that in special situations the spectra from uncoupled systems may exhibit fringes. Suppose that the system symmetry allows discrete domain states (e.g., corresponding to in-plane easy axes), and that the average domain size and the superlattice period are both small in comparison to the coherence length of the incident neutron wave (since the coherence length in a typical experiment is of the order of 1000 Å, this is not an unusual situation). Then, arguably, there is always a finite probability that equivalent domains located in different layers will fall into the “coherence volume,” and give rise to constructive interference, even though the domains are not coupled by any interactions. In view of that, our work included simulations on several different model systems that might, in principle, exhibit such an effect. Again, the averaged data from many thousands of runs showed no anomalies at the expected fringe positions, providing more evidence that neutron diffraction allows a fully reliable distinction of coupled and uncoupled superlattice systems.

Effect of detector noise on the positioning accuracy of an autofocus system

An autofocus system has been developed that automatically detects the presence of fringes in a white-light interference microscope and adjusts the vertical position of the microscope objective such that the focus error is minimal. The system consists of a motorized stage, a beam splitter, an optical detector, and associated electronics. In order for the interference microscope to provide accurate measurements of the optical wavefront, the error in the focus position must be small. The goal of this paper is to calculate the rms noise produced by the detector and electronics and use the results to predict the positioning error of the autofocus system.

Spectral dominance in sensitivity to interaural delay for broadband stimuli

Just-noticeable differences (jnds) in interaural delay of a target band were measured in the presence of a diotic spectral fringe. Stimuli were clicks or 100-ms bursts of noise with flat spectra from 0.1 to 9 kHz. The bandwidth of the target band was 0.4 times the center frequency. With either clicks or noise, the jnds for target bands having center frequencies between 0.5 and 1 kHz were roughly unaffected by the presence of the fringe: They were on the order of tens of microseconds. In contrast, the jnds for target bands at high frequencies were greatly degraded by the presence of the fringe: They increased from approximately 100 μs to greater than 600 μs. With noise, delaying a low-frequency target band causes the image of that band to separate from the image of the fringe. With clicks, delaying a low-frequency band (with about 3% of the total energy) causes the entire wideband image to lateralize. In general, the results suggest that the degree of the dominance region described by Bilsen and Raatgever [Acustica 28, 131–132 (1973)] is virtually total and that interaural delays at high frequencies are insignificant compared to those at low frequencies. [Work supported by NIH.]

X‐Ray interference fringes and domain arrangements in Fe + 3 wt% Si single crystals

AbstractExperimental observations on the anomalous transmission of X‐rays through a single crystal of Fe + 3 wt % Si having a regular domain arrangement are reviewed and discussed. The contrast lines present in these transmission photographs are interpreted as X‐ray interference fringes which are shown to run perpendicular to the domain boundaries seen on the crystal by the Bitter technique. From the presence of fringes in both the anomalously diffracted and transmitted beams it is inferred that the dynamical theory of X‐ray diffraction is necessary to explain this effect. The orientation of these fringes and their appearance and disappearance as a function of the diffracting plane are derived using the dynamical theory of diffraction in a medium containing magnetic domain boundaries in the path of the X‐ray beam. The observed dependence of fringe spacing on X‐ray wavelength is also quantitatively explained by this calculation.