Search

We report 4 new pulsars discovered in the core-collapsed globular cluster (GC) NGC 6624 by the TRAPUM Large Survey Project with the MeerKAT telescope. All of the new pulsars found are isolated. PSR J1823$-$3021I and PSR J1823$-$3021K are millisecond pulsars with period of respectively 4.319 ms and 2.768 ms. PSR J1823$-$3021J is mildly recycled with a period of 20.899 ms, and PSR J1823$-$3022 is a long period pulsar with a period of 2.497 s. The pulsars J1823$-$3021I, J1823$-$3021J, and J1823$-$3021K have position and dispersion measure (DM) compatible with being members of the GC and are therefore associated with NGC 6624. Pulsar J1823$-$3022 is the only pulsar bright enough to be re-detected in archival observations of the cluster. This allowed the determination of a timing solution that spans over two decades. It is not possible at the moment to claim the association of pulsar J1823$-$3022 with the GC given the long period and large offset in position ($\sim 3$ arcminutes) and DM (with a fractional difference of 11 percent compared the average of the pulsars in NGC 6624). The discoveries made use of the beamforming capability of the TRAPUM backend to generate multiple beams in the same field of view which allows sensitive searches to be performed over a few half-light radii from the cluster center and can simultaneously localise the discoveries. The discoveries reflect the properties expected for pulsars in core-collapsed GCs., Accepted for publication on Monthly Notices of the Royal Astronomical Society. 11 pages, 6 figures

The most massive globular cluster in our Galaxy, Omega Centauri, is an interesting target for pulsar searches, because of its multiple stellar populations and the intriguing possibility that it was once the nucleus of a galaxy that was absorbed into the Milky Way. The recent discoveries of pulsars in this globular cluster and their association with known X-ray sources was a hint that, given the large number of known X-ray sources, there is a much larger undiscovered pulsar population. We used the superior sensitivity of the MeerKAT radio telescope to search for pulsars in Omega Centauri. In this paper, we present some of the first results of this survey, including the discovery of 13 new pulsars; the total number of known pulsars in this cluster currently stands at 18. At least half of them are in binary systems and preliminary orbital constraints suggest that most of the binaries have light companions. We also discuss the ratio between isolated and binaries pulsars, and how they were formed in this cluster.

PSRJ1910-5959A (J1910A) is a binary millisecond pulsar in a 0.837 day circular orbit around a helium white dwarf (HeWD) companion. This pulsar is located 6.3 arcmin away from the centre of the globular cluster NGC6752. Given the large offset, the association of the pulsar to NGC6752 has been debated. We have made use of two decades of archival Parkes 64-m "Murriyang" telescope data and recently carried out observations with the MeerKAT telescope. We obtained Pulse times of arrival using standard data reduction techniques and analysed using Bayesian pulsar timing techniques. We analysed the pulsar's total intensity and polarisation profile, to study the interstellar scattering along the line of sight, and the pulsar's geometry by applying the rotating vector model. We obtain precise measurements of several post-Keplerian parameters: the range $r=0.202(6)T_\odot$ and shape s=0.999823(4) of the Shapiro delay, from which we infer the orbital inclination to be $88.9^{+0.15}_{-0.14}\deg$ and the masses of both the pulsar and the companion to be $1.55(7)M_{\odot}$ and $0.202(6)M_{\odot}$ respectively; a secular change in the orbital period $\dot{P}_{\rm b}=-53^{+7.4}_{-6.0}\times 10^{-15}$\,s\,s$^{-1}$ that proves the association to NGGC6752 and a secular change in the projected semi-major axis of the pulsar $\dot{x}= -40.7^{+7.3}_{-8.2}\times10^{-16}$\,s\,s$^{-1}$ that is likely caused by the spin-orbit interaction from a misaligned HeWD spin, at odds with the likely isolated binary evolution of the system. We also discuss some theoretical models for the structure and evolution of WDs in NS-WD binaries by using J1910A's companion as a test bed. J1910A is a rare system for which several parameters of both the pulsar and the HeWD companion can be accurately measured. As such, it is a test bed to discriminate between alternative models for HeWD structure and cooling., Comment: 18 pages, 12 figures. Abstract shortened and rephrased because of arXiv characters limits. Accepted for publication on A&A on January 9th 2023 Updated version after linguistic revision

PSR J2140$-$2311B is a 13-ms pulsar discovered in 2001 in a 7.8-hour Green Bank Telescope (GBT) observation of the core-collapsed globular cluster M30 and predicted to be in a highly eccentric binary orbit. This pulsar has eluded detection since then, therefore its precise orbital parameters have remained a mystery until now. In this work, we present the confirmation of this pulsar using observations taken with the UHF receivers of the MeerKAT telescope as part of the TRAPUM Large Survey Project. Taking advantage of the beamforming capability of our backends, we have localized it, placing it $1.2(1)^\prime$ from the cluster centre. Our observations have enabled the determination of its orbit: it is highly eccentric ($e = 0.879$) with an orbital period of $6.2$ days. We also measured the rate of periastron advance, $\dot{\omega} = 0.078 \pm 0.002\, \rm deg \, yr^{-1}$. Assuming that this effect is fully relativistic, general relativity provides an estimate of the total mass of the system, $M_{\rm TOT} = 2.53 \pm 0.08$ M$_{\odot}$, consistent with the lightest double neutron star systems known. Combining this with the mass function of the system gives the pulsar and companion masses of $m_p < 1.43 \, \rm M_{\odot}$ and $m_c > 1.10 \, \rm M_{\odot}$ respectively. The massive, undetected companion could either be a massive WD or a NS. M30B likely formed as a result of a secondary exchange encounter. Future timing observations will allow the determination of a phase-coherent timing solution, vastly improving our uncertainty in $\dot{\omega}$ and likely enabling the detection of additional relativistic effects which will determine $m_p$ and $m_c$., Comment: Accepted for publication in the Astrophysical Journal Letters (ApJL)

We report the discovery of 13 new pulsars in the globular cluster NGC 1851 by the TRAPUM Large Survey Project using the MeerKAT radio telescope. The discoveries consist of six isolated millisecond pulsars (MSPs) and seven binary pulsars, of which six are MSPs and one is mildly recycled. For all the pulsars, we present the basic kinematic, astrometric, and orbital parameters, where applicable, as well as their polarimetric properties, when these are measurable. Two of the binary MSPs (PSR J0514−4002D and PSR J0514−4002E) are in wide and extremely eccentric (e > 0.7) orbits with a heavy white dwarf and a neutron star as their companion, respectively. With these discoveries, NGC 1851 is now tied with M28 as the cluster with the third largest number of known pulsars (14). Its pulsar population shows remarkable similarities with that of M28, Terzan 5, and other clusters with comparable structural parameters. The newly found pulsars are all located in the innermost regions of NGC 1851 and will likely enable, among other things, detailed studies of the cluster structure and dynamics.

PSR J0540$-$6919 is the second-most energetic radio pulsar known and resides in the Large Magellanic Cloud. Like the Crab pulsar it is observed to emit giant radio pulses (GPs). We used the newly-commissioned PTUSE instrument on the MeerKAT radio telescope to search for GPs across three observations. In a total integration time of 5.7 hrs we detected 865 pulses above our 7$\sigma$ threshold. With full polarisation information for a subset of the data, we estimated the Faraday rotation measure, $\rm{RM}=-245.8 \pm 1.0$ rad m$^{-2}$ toward the pulsar. The brightest of these pulses is $\sim$ 60% linearly polarised but the pulse-to-pulse variability in the polarisation fraction is significant. We find that the cumulative GP flux distribution follows a power law distribution with index $-2.75 \pm 0.02$. Although the detected GPs make up only $\sim$ 10% of the mean flux, their average pulse shape is indistinguishable from the integrated pulse profile, and we postulate that there is no underlying emission. The pulses are scattered at L-band frequencies with the brightest pulse exhibiting a scattering time-scale of $\tau = 0.92 \pm 0.02$ ms at 1.2 GHz. We find several of the giants display very narrow-band "flux knots" similar to those seen in many Fast Radio Bursts, which we assert cannot be due to scintillation or plasma lensing. The GP time-of-arrival distribution is found to be Poissonian on all but the shortest time-scales where we find four GPs in six rotations, which if GPs are statistically independent is expected to occur in only 1 of 7000 observations equivalent to our data., Comment: 15 pages, 10 figures

We describe the ongoing Relativistic Binary programme (RelBin), a part of the MeerTime large survey project with the MeerKAT radio telescope. RelBin is primarily focused on observations of relativistic effects in binary pulsars to enable measurements of neutron star masses and tests of theories of gravity. We selected 25 pulsars as an initial high priority list of targets based on their characteristics and observational history with other telescopes. In this paper, we provide an outline of the programme, present polarisation calibrated pulse profiles for all selected pulsars as a reference catalogue along with updated dispersion measures. We report Faraday rotation measures for 24 pulsars, twelve of which have been measured for the first time. More than a third of our selected pulsars show a flat position angle swing confirming earlier observations. We demonstrate the ability of the Rotating Vector Model (RVM), fitted here to seven binary pulsars, including the Double Pulsar (PSR J0737$-$3039A), to obtain information about the orbital inclination angle. We present a high time resolution light curve of the eclipse of PSR J0737$-$3039A by the companion's magnetosphere, a high-phase resolution position angle swing for PSR J1141$-$6545, an improved detection of the Shapiro delay of PSR J1811$-$2405, and pulse scattering measurements for PSRs J1227$-$6208, J1757$-$1854, and J1811$-$1736. Finally, we demonstrate that timing observations with MeerKAT improve on existing data sets by a factor of, typically, 2-3, sometimes by an order of magnitude., 21 pages 16 figures, published in MNRAS (replaced earlier submission after small changes added in proofs)

Using the state-of-the-art SKA precursor, the MeerKAT radio telescope, we explore the limits to precision pulsar timing of millisecond pulsars achievable due to pulse stochasticity (jitter). We report new jitter measurements in 15 of the 29 pulsars in our sample and find that the levels of jitter can vary dramatically between them. For some, like the 2.2~ms pulsar PSR J2241--5236, we measure an implied jitter of just $\sim$ 4~ns/hr, while others like the 3.9~ms PSR J0636--3044 are limited to $\sim$ 100 ns/hr. While it is well known that jitter plays a central role to limiting the precision measurements of arrival times for high signal-to-noise ratio observations, its role in the measurement of dispersion measure (DM) has not been reported, particularly in broad-band observations. Using the exceptional sensitivity of MeerKAT, we explored this on the bright millisecond pulsar PSR J0437--4715 by exploring the DM of literally every pulse. We found that the derived single pulse DMs vary by typically 0.0085 cm$^{-3}$ pc from the mean, and that the best DM estimate is limited by the differential pulse jitter across the band. We postulate that all millisecond pulsars will have their own limit on DM precision which can only be overcome with longer integrations. Using high-time resolution filterbank data of 9 $\mu$s, we also present a statistical analysis of single pulse phenomenology. Finally, we discuss optimization strategies for the MeerKAT pulsar timing program and its role in the context of the International Pulsar Timing Array (IPTA)., Comment: 16 pages, 9 figures

We have used the central 44 antennas of the new 64-dish MeerKAT radio telescope array to conduct a deep search for new pulsars in the core of nine globular clusters. This has led to the discovery of eight new millisecond pulsars in six different clusters. Two new binaries, 47 Tuc ac and 47 Tuc ad, are eclipsing "spiders", featuring compact orbits ($\lesssim 0.32$ days), very low-mass companions and regular occultations of their pulsed emission. The other three new binary pulsars (NGC 6624G, M62G, and Ter 5 an) are in wider ($> 0.7$ days) orbits, with companions that are likely to be white dwarfs or neutron stars. NGC 6624G has a large eccentricity of $e\simeq 0.38$, which enabled us to detect the rate of advance of periastron. This suggests that the system is massive, with a total mass of $M{\rm tot} = 2.65 \pm 0.07$ M$_{\odot}$. Likewise, for Ter 5 an, with $e \simeq 0.0066$, we obtain $M{\rm tot}= 2.97 \pm 0.52$ M$_{\odot}$. The other three new discoveries (NGC 6522D, NGC 6624H and NGC 6752F) are faint isolated pulsars. Finally, we have used the whole MeerKAT array and synthesized 288 beams, covering an area of $\sim2$ arcmin in radius around the center of NGC 6624. This has allowed us to localize many of the pulsars in the cluster, demonstrating the beamforming capabilities of the TRAPUM software backend and paving the way for the upcoming MeerKAT globular cluster pulsar survey., 20 pages, 10 figures. Accepted for publication in Monthly Notices of the Royal Astronomical Society

Introduction: Severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2), first reported from the Wuhan city of China in December 2019, swept the world in a few months and became a global health emergency of primary international concern continues to be a priority health problem. Recent studies suggest that subjects with autoimmune disorders (JIA, RA, SLE) do not have an increased risk to get Sars-Cov2. Juvenile Idiopathic Arthritis (JIA) is an inflammatory chronic disease concerning joints and others structures. According to International League of Association for Rheumatology (ILAR) seven subtypes of arthritis can be defined in relation with the number of joints and the extra-articular involvement occurring in the first six months of disease. NSAIDs and intra-articular steroids represent the first line treatment for JIA. Systemic steroids, disease modifying anti-rheumatic drugs (DMARDs) and biologic drugs are used in children with severe disease. Objectives: To evaluate the incidence and the impact on the disease course of Sars-cov2 infection in a group of children affected from juvenile idiopathic arthritis in treatment with Methotrexate and/or biological drugs. Methods: This study includes 77 children affected from JIA (55 females, 22 males). JIA diagnosis was made according to ILAR criteria and treatment was assigned with recommendations of the American College of Rheumatology. For each patient we recorded the type and the duration of pharmacological treatment, JIA subtype and relapses (defined according to Wallace criteria). During follow up visit from Nov 1st, 2020 to April 30th, 2021 we investigated in each patient history of Sars-Cov2 infection and related symptoms, diagnostic tests for Sars-Cov2. Results: The mean age at the last follow-up visit was 13.3±5.61 years. Thirteen out of 77 patients was affected Sars-Cov2 infection, none of them needed to be hospitalized. The most common symptom was headache (8 of 13 patients), followed by myalgia (6 of 13), fever (4 of 13), anosmia or dysgeusia (3 of 13), upper respiratory tract symptoms (3 of 13) and nausea (3 of 13). Five out of 13 patients were asymptomatic (38,5%). The mean duration of Sars-Cov2 infection was 12,5 days (confirmed with nose pharyngeal swab). In the group of patients with Sars-Cov2 infection 4 of 13 (30%) were in treatment with MTX, 2 of 13 (15%) with both MTX and biological drugs, 5 of 13(38%) with biological drugs, 2 of 13 (15%) with NSAIDs. In the group of patients without Sars-Cov2 infection 37 of 64 (48%) patients were in treatment with MTX, 32 of 64 (41,5%) with biological drugs, 18 of 64 (28%) with both MTX and biological drugs, 10 of 64 (15,6%) with NSAIDs. We didn’t find a higher risk to contract Sars-Cov2 infection in patients under MTX treatment (48% vs 46.15 %; p value 0.6416), in ones under MTX and biological drugs (28.1% vs 15.4%p value 0.543) or in ones under only biological therapy (50% vs 53.8% ; p value 0.231). We found that in patient with JIA the risk to get Sars-Cov2 infection is not related to the treatment. The percentage of JIA relapses was higher in patients with Sars-Cov2 infection than in the ones without infection (53,8% vs 9%; p value 0.0004). Conclusion: Treatment with MTX or biological drugs did not increase the risk to get Sars-Cov2 infection. The frequency of JIA relapses was higher in patients who got Sars-Cov2 infection than in ones who didn’t get it

The millisecond pulsar J1823-3021A is a very active giant pulse emitter in the globular cluster NGC 6624. New observations with the MeerKAT radio telescope have revealed 14350 giant pulses over 5 hours of integration time, with an average wait time of about 1 second between giant pulses. The giant pulses occur in phases compatible with the ordinary radio emission, follow a power-law distribution with an index of -2.63 $\pm$ 0.02 and contribute 4 percent of the total integrated flux. The spectral index of the giant pulses follows a Gaussian distribution centered around -1.9 with a standard deviation of 0.6 and is on average flatter than the integrated emission, which has a spectral index of -2.81 $\pm$ 0.02. The waiting times between the GPs are accurately described by a Poissonian distribution, suggesting that the time of occurrence of a GP is independent from the times of occurrence of other GPs. 76 GPs show multiple peaks within the same rotation, a rate that is also compatible with the mutual independence of the GP times of occurrence. We studied the polarization properties of the giant pulses finding, on average, linear polarization only at the 1 percent level and circular polarization at the 3 percent level, similar to the polarization percentages of the total integrated emission. In 4 cases it was possible to measure the RM of the GPs which are highly variable and, in two cases, is inconsistent with the mean RM of the total integrated pulsar signal., Comment: Accepted for publication in MNRAS. 8 Pages, 11 Figures

We report the use of a low oxygen partial pressure dry furnace oxidation process for the fabrication of ultra-thin compressively strained SGOI layers. The effect of a reduced oxygen partial pressure on oxidation kinetics and Ge depth profile evolution is shown. Resulting strain, SiGe surface and roughness evaluation are carried out to compare the residual strain values and the crystal defects generation to results obtained with a conventional pure oxygen process.

To co-integrate bipolar devices with 28 nm FDSOI CMOS using the epitaxial extrinsic base isolated from the collector architecture, an epitaxy is needed on a pre-implanted SOI. The issue of thin film agglomeration induced by epitaxy pre-bake is addressed. Particularly, it is shown that high dose implantation induced damages and point defects lead to a decrease of the SOI critical temperature of agglomeration. In this study, heated implantation is proposed in order to solve this issue.

The optical response of strained SiGe alloys, as well as thin Si layers, is analyzed using a sp 3 d 5 s ∗ tight-binding model within the independent particle approximation. The theoretical results are compared to measurements obtained on samples with various Ge content and layer thicknesses. The dielectric function is extracted from spectroscopic ellipsometry allowing a separation of its real and imaginary parts. Theory and simulation show similar trends for the variation of the dielectric function of SiGe with varying Ge content. Variations are also well reproduced for thin Si layers with varying thickness and are attributed to quantum confinement.

International audience; The fabrication of ultrathin compressively strained SiGe-On-Insulator layers by the condensation technique is likely a key milestone towards low-power and high performances FD-SOI logic devices. However, the SiGe condensation technique still requires challenges to be solved for an optimized use in an industrial environment. SiGe oxidation kinetics, upon which the condensation technique is founded, has still not reached a consensus in spite of various studies which gave insights into the matter. This paper aims to bridge the gaps between these studies by covering various oxidation processes relevant to today's technological needs with a new and quantitative analysis methodology. We thus address oxidation kinetics of SiGe with three Ge concentrations (0%, 10%, and 30%) by means of dry rapid thermal oxidation, in-situ steam generation oxidation, and dry furnace oxidation. Oxide thicknesses in the 50 angstrom to 150 angstrom range grown with oxidation temperatures between 850 and 1100 degrees C were targeted. The present work shows first that for all investigated processes, oxidation follows a parabolic regime even for thin oxides, which indicates a diffusion-limited oxidation regime. We also observe that, for all investigated processes, the SiGe oxidation rate is systematically higher than that of Si. The amplitude of the variation of oxidation kinetics of SiGe with respect to Si is found to be strongly dependent on the process type. Second, a new quantitative analysis methodology of oxidation kinetics is introduced. This methodology allows us to highlight the dependence of oxidation kinetics on the Ge concentration at the oxidation interface, which is modulated by the pile-up mechanism. Our results show that the oxidation rate increases with the Ge concentration at the oxidation interface. Published by AIP Publishing.

High mobility channels are considered as an interesting path to increase PMOS performances for advanced CMOS technology. Silicon-Germanium On Insulator (SGOI) benefits from both the advantage of the SiGe material (hole mobility booster) and the On Insulator structure (better electrostatic control of the channel by the gate) [1]. The co-integration of NMOS and PMOS, respectively on Silicon On Insulator (SOI) and SGOI zones, can be enabled easily by the Ge condensation technique [1,2]. This technique is based on the competition between Ge diffusion and Si oxidation which are both driven by temperature. For this purpose, mainly furnace oxidation is reported in the literature [1-3]. In this work, we propose to study Ge condensation using Rapid Thermal Oxidation (RTO) as an alternative process. SGOI structures were fabricated on 300mm SOI wafers, with 11nm thick top silicon. First, epitaxy layers of SiGe were grown with varying thickness (from 3 to 10nm) and Ge concentration (from 10 to 40%). The SiGe film was grown by Rapid Thermal Chemical Vapor Deposition at temperature between 600°C and 650°C. Then, Ge condensation was performed by RTO in O2 ambient at temperatures between 950°C and 1150°C. Both aspects of Ge condensation were studied: Ge diffusion then Si oxidation. The RTO temperature effect on Ge diffusion was analysed by ToF-SIMS (Figure 1). In the case of short oxidation duration (below 2 minutes), as typically used in RTO compared to furnace (several hours), almost no diffusion is observed at 950°C. This leads to Ge enrichment of the initial SiGe layer with Ge concentration gradient. For longer oxidation, this might result in very high Ge concentration generating strain relaxation via stacking fault creation [4]. Therefore, temperatures above 950°C are prefered to avoid defects creation. TEM and STEM-EDX of the structure after condensation (Figure 2) shows that Ge concentration is still not totally homogeneous at 1100°C. Oxidation kinetics is shown on Figure 3, comparing the effect of substrate: SiGe/Si/BOX vs Si. SiGe is oxidized faster than Si, as already reported [5,6]. Moreover, SiGe oxidation is enhanced with increasing Ge concentration. Same trend is observed concerning SiGe thickness, indicating the effect of Ge diffusion in the underneath Si layer. A compositional analysis of the oxide grown by condensation was performed by XPS, monitoring the Ge3d peak (Figure 4). Starting from the same SiGe/Si/BOX structure, the oxide thickness was kept the same using different RTO temperatures but tuning the O2 pressure and the RTO duration. The effect of Ge diffusion is clearly observed by the intensity of the Ge-Si contribution. Higher temperature leads to lower Ge concentration due to a more homogeneous Ge distribution. Surprisingly, Ge-O bounds are also observed, whereas SixGe1-xalloy oxidation is thermodynamically considered to be Si selective [7]. Moreover, the amount of Ge-O bounds increases when the RTO temperature decreases. As shown previously, low temperature oxidation leads to high Ge concentration at the SiO2/SiGe interface, which may enable the formation of Ge-O bounds [8]. As a consequence, oxidation kinetics plays an important role in this phenomenon. This study reveals the significant role of temperature in Ge condensation by RTO. Due to kinetics effect, Ge-O bounds are formed which is not predicted by thermodynamics. Finally, the role of temperature will be investigated through electrical characterization of the SixGeyO properties. [1] B. Vincent at al, Mat. Sc. Semicond. Proc. 11, 2008 [2] T. Tezuka et al., Jpn. J. Appl. Phys. 40, 2886, 2001. [3] Z. Di et al., J. Crystal Growth 281, 2005 [4] B. Vincent, Appl. Phys. Lett. 90, 2007 [5] O. W. Holland et al., Appl. Phys. Lett. 51, 7, 1987 [6] S. J. Kilpatrick et al., J. Appl. Phys. 81, 12, 1997 [7] D. C. Paine et al, J. Appl. Phys. 70, 5076, 1991 [8] J. Eugene, Appl. Phys. Lett. 59, 78, 1991

The demand for higher speed and lower power consumption ICs has motivated research for higher mobility channel materials (1). Compressively strained SiGe is known to feature higher hole mobility than Si and is largely compatible with the Si CMOS manufacturing platform. Besides, the FDSOI transistor architecture allows power consumption reduction (2), thus making SiGe-On-Insulator (SGOI) channels promising. SGOI layers can be fabricated by the so-called condensation technique, which is based on concurrent Si selective thermal oxidation of SiGe and SiGe composition homogenization by Si and Ge interdiffusion (see Figure 1) (3). Therefore, a sound understanding of kinetics of oxidation and interdiffusion of SiGe is required to develop optimized SGOI structures. SiGe dry oxidation rate has been reported to be higher (4) than or equal (5)(6) to the one of Si. It therefore remains unclear. Few groups investigated Rapid Thermal Oxidation (RTO) (4) while most of them looked at furnace oxidation. Moreover, most studies only considered the initial Ge content to compare oxidation kinetics. Indeed, the Ge concentration below the SiGe-oxide interface is strongly varying with time because of two mechanisms: firstly, the Si-selective oxidation of SiGe tends to pile-up Ge below the oxidizing interface; and secondly, interdiffusion of SiGe favors homogenization of the layer (6). This paper focuses on the oxidation rate of SiGe in regards to the varying Ge concentration in the SiGe layer for various oxidation conditions. Thick (> 20 nm) SiGe layers with either 10% or 30% Ge concentrations were epitaxially grown on bulk Si wafers. Oxidation was performed by RTO in 1 atmosphere of pure O2, with different oxidation temperatures and durations. Oxide thickness and SiGe composition versus depth were measured by Spectroscopic Ellipsometry and X-Ray Reflectivity, and by Secondary Ion Mass Spectroscopy respectively. Figure 2 shows the Ge concentration profile below the oxide. A rapid creation of a pile-up layer is observed at all temperatures. Then, three regimes of evolution of the pile-up layer are distinguished: the Ge concentration at the oxidizing interface (a) increases, (b) is constant, and (c) decreases. The regime of evolution of the pile-up layer is determined by a competition between the oxidation speed and the interdiffusion speed. As schematically illustrated Figure 3, the interdiffusion speed overcomes the oxidation one at higher temperatures because the activation energy of interdiffusion in SiGe ([4,5] eV (7)) is well above the one of SiGe oxidation ([2,2.6] eV (4)). Phrased in a different way, the temperature dependence of interdiffusion is higher than the oxidation one. Figure 4 shows the oxide thickness versus the oxidation duration for dry RTO at 900°C, 1000°C and 1100°C. A higher oxidation rate is observed for SiGe compared to Si for all temperatures. Then, to highlight the effect of the Ge concentration at the oxidizing interface, we fitted the curves to extract oxidation rates for each oxidation conditions. We define the Growth Rate Enhancement (GRE) as the ratio of the oxidation rate of SiGe to the one of Si at a given oxide thickness and for identical oxidation conditions. It is indeed important to highlight that comparing oxidation rates at the same oxide thickness is mandatory: if we want to examine the effect of Ge on the oxidation rate, we have to take into consideration the fact that the oxidation rate also decreases with the oxide thickness. Such an approach allows us to freeze the system and to find more easily correlations. We report on Figure 5 four GRE values extracted from our data versus the Ge concentration at the oxidizing interface. We thus observe that the higher the Ge concentration at the oxidizing interface is, the higher the GRE tends to be. We thus showed that Ge redistribution by interdiffusion during SiGe oxidation can follow different regimes. We also evidenced that for dry RTO conditions, the higher the Ge concentration at the oxidizing interface is, the higher the GRE is. Understanding the interdependence of these two mechanisms is essential to get an accurate picture of the condensation process. Therefore, data for dry RTO will be completed and an in-depth discussion will be led. A similar study will also be conducted for a wet oxidation process called In-Situ Steam Generation (ISSG). (1) Pillarisetty, R., Nature 479.7373 (2011): 324-328. (2) Weber, O., et al., VLSIT IEEE, 2014. (3) Tezuka, T., et al., JJAP 40.4S (2001): 2866. (4) Spadafora, M., et al. MSSP 8.1 (2005): 219-224. (5) LeGoues, et al., APL 54.7 (1989): 644-646. (6) Long, E., et al., PSS (a) 209.10 (2012): 1934-1939. (7) Kube, R., et al., JAP 107.7 (2010): 073520. Figure 1

In this paper we explore for the first time the impact of an ultra-thin BOX (UTBOX) with and without ground plane (GP) on a 32 nm fully-depleted SOI (FDSOI) high-k/metal gate technology. The performance comparison versus thick BOX architecture exhibits a 50 mV DIBL reduction by using 10 nm BOX thickness for NMOS and PMOS devices at 33 nm gate length. Moreover, the combination of DIBL reduction and threshold voltage modulation by adding GP enables to reduce the Isb current by a factor 2.8 on a 0.299μm2 SRAM cell while maintaining an SNM of 296 mV@Vdd 1.1 V.

We present an original experimental approach developed to extract with a good level of accuracy and confidence the optical properties of SOI layers for several thicknesses ranging from 3nm up to 12nm. The measurements were done using a spectroscopic ellipsometer in conjunction with an x-ray reflectometer. The instrumental function of the ellipsometer was first characterized experimentally to minimize systematic errors. A specific experimental protocol was then used to produce SOI Silicon layers and extract their optical properties. The resulting dispersion models were tested on other sample structures to check the validity of the models.

This paper presents the first 55 nm SiGe BiCMOS technology developed on a 300 mm wafer line in STMicroelectronics. The technology features Low Power (LP) and General Purpose (GP) CMOS devices and 0.45 µm2 6T-SRAM bit cell. High Speed (HS) HBT exhibits 320 GHz f T and 370 GHz f MAX associated with a CML ring oscillator gate delay τ D of 2.34 ps. Transmission lines, capacitors, high-Q varactors and inductors dedicated to millimeter-wave applications are also available.

Los inhibidores de la enzima convertidora de la angiotensina (IECA) han demostrado ser eficaces en el tratamiento de la hipertensión arterial. Sin embargo, una importante proporción de hipertensos recibe además antiagregación plaquetaria con ácido acetil salicílico (AAS), y la consecuente inhibición de la síntesis de prostaglandinas con AAS atenuaría el efecto vasodilatador y la mayor excreción urinaria de sodio (Na u) atribuidas al IECA. Nuestro objetivo fue evaluar la interacción de dos dosis de AAS (81 y 325 mg/día) sobre el efecto hipotensor del enalapril y el impacto sobre la excreción de Na u en pacientes hipertensos. Se incluyeron 22 pacientes de ambos sexos, entre 35 y 65 años. Todos recibieron enalapril, dieta hiposódica y, secuencialmente separadas por período de «wash out», las dos dosis de AAS durante los setenta días del estudio. Se evaluó: presión arterial sistólica (PAS), diastólica (PAD), media (PAM) y Na u en un período basal (PB), con 325 y 81 mg de AAS (P1 y P2 respectivamente). Comparando el PB con P1 y P2, se observó una reducción significativa de la PAS, PAD, PAM (pAngiotensin converting enzyme inhibitors have been shown to be useful in the treatment of essential hypertension while anti-platelet agents improve the overall cardiovascular risk profile in this population. Our aim was to assess the interaction of two different aspirin (ASA) doses -81 and 325 mg/day- with the antihypertensive effect of enalapril as well as their impact upon the urinary sodium excretion (Na u). A total of 22 patients between 35 and 65 years of age were included in a prospective double blind trial with a partial cross-over design. We excluded patients with secondary hypertension and recent use of anti-inflammatory drugs. Patients were placed on enalapril and a low sodium diet

This paper presents a 14nm technology designed for high speed and energy efficient applications using strain-engineered FDSOI transistors. Compared to the 28nm FDSOI technology, this 14nm FDSOI technology provides 0.55× area scaling and delivers a 30% speed boost at the same power, or a 55% power reduction at the same speed, due to an increase in drive current and low gate-to-drain capacitance. Using forward back bias (FBB) we experimentally demonstrate that the power efficiency of this technology provides an additional 40% dynamic power reduction for ring oscillators working at the same speed. Finally, a full single-port SRAM offering is reported, including an 0.081°m 2 high-density bitcell and two 0.090°m 2 bitcell flavors used to address high performance and low leakage-low Vmin requirements.

This paper presents a study performed to evaluate the benefits of combining techniques to improve the overall metrology of thin Silicon Germanium (SiGe) epitaxial layers doped with Boron. A specifically-designed set of wafers was processed and measured by different in-line metrology tools and characterization techniques. This study describes the best strategy for combining metrology techniques in order to reliably determine dopant concentration and Ge composition measurement of the layers. It demonstrates that combined metrology enables key improvements in manufacturing and engineering environments.

Tuberculosis is a diffusive infectious disease whose typical behavior differentiates it from other infectious diseases spread by human-to-human transmission (flu, chicken pox, cholera, etc.) which follow a classically epidemic pattern. Indeed, in the presence of a known source of Koch bacilli capable of spreading them by air, not all exposed individuals inhale the bacteria, not all those who inhale them absorb them, not all those who absorb them are unable to eliminate them, not all who are able to eliminate them do so using delayed hypersensitivity, not all those who react with delayed hypersensitivity suffer lasting tissue damage (among other things, minor), not all who suffer tissue damage have anatomical sequelae, not all those who have anatomical sequelae, however minimal, become carriers of bacilli in the latent period. The vast majority (90-95%) of the latter – which are in any case a portion, not the totality of those exposed – remain asymptomatic throughout their lives and never develop active tuberculosis. Based on these biological characteristics and the legal concepts of “epidemic” and “disease,” it becomes highly problematic, if not impossible, to assert both that tuberculosis can cause events of sufficient magnitude to be associated with the crime of “epidemic,” and that the mere diagnosis of a latent tuberculosis infection is sufficient to assume the presence of an illness legally prosecutable in criminal proceedings or a disability prosecutable in civil proceedings. Further, clinically apparent tuberculosis is a temporarily—in some cases permanently—disabling condition, and in certain work environments, even with the difficulties caused by the lack of available effective diagnostic tools and the insidious behavior of the disease in the early stages, it appears appropriate to engage in targeted monitoring, also for the early identification of persons who may become ill.

We studied the effects of (post-tetanic) potentiation on myosin light chain (MLC-2) phosphorylation, work and energy cost in skeletal muscle. Experiments were performed using in situ medial gastrocnemius muscles of male Wistar rats, which were electrically stimulated through the severed sciatic nerve. One group of muscles was first potentiated with an isometric tetanus before a series of 10 concentric contractions (PRC). A second group performed the same series of contractions without previous potentiation (RC). Following the last contraction the muscles were rapidly frozen and excised after which the high-energy phosphate content, lactate concentration and the level of MLC-2 phosphorylation were measured. The results indicate that PRC muscles had a higher (P < 0.05) total work output 144.5 ± 17.0 (SD) (n = 6) vs. 121.6 ± 11.4 (SD) (n = 6) mJ and level of MLC-2 phosphorylation (49.2 ± 7.3 vs. 40.8 ± 3.6%) than RC muscles. The energy cost of the series of concentric contractions in the PRC muscles (9.8 ± 1.9 μmol∼P/muscle) was significantly higher (P < 0.05) than the energy cost in the RC muscles (6.2 ± 0.97 μmol∼P/muscle). It was shown that the relative increase in energy cost of PRC muscles was higher (P < 0.05) than in total work output. It is proposed that the relative high increase in energy cost is the direct result of the increase in muscle performance rather than a property of potentiation.

Quite recently quantum features exhibited by a mesoscopic field interacting with a single Rydberg atom in a microwave cavity has been observed [A. Auffeves et al., Phys. Rev. Lett. 91, 230405 (2003)]. In this paper we theoretically analyze all the phases of this articulated experiment considering from the very beginning cavity losses. Fully applying the theory of quantum open systems, our modelization succeeds in predicting fine aspects of the measured quantity, reaching qualitative and quantitative good agreement with the experimental results. This fact validates our theoretical approach based on the fundamental atom-cavity interaction model and simple mathematical structure of dissipative superoperators.

Neurotrophins are growth factors acting on responsive cells through membrane receptors identified as Trk tyrosine kinase proteins (A, B and C). Trks are present in the mammalian lymphoid organs, and indirect evidence suggests that they are also present in the avian bursa of Fabricius. This study was designed to analyze (a) the occurrence and localization of Trk proteins in the bursa of Fabricius; and (b) whether the post-hatching growth of the organ (from hatching to 75 days) involves cells expressing Trk proteins. We used pigeon bursae of Fabricius, and rabbit polyclonal antibodies against specific epitopes of TrkA, TrkB and TrkC. Cytokeratins and vimentin were studied in parallel with label non-lymphoid cells of the bursal follicles. Immunoreactivity (IR) for all assessed antigens was found in specific non-lymphoid cells. From hatching to 15 days, TrkB-like IR was found outside the follicles in cells localized beneath the follicle associated (FAE) and interfollicular (IFE) epithelium. Between 30–75 days TrkB-like IR labelled the medullary secretory dendritic cells (SDC). The density of SDC displaying IR increased up to 60 days. TrkA-like and TrkC-like IR was primarily observed in FAE and IFE, but also in the medullary reticular epithelial cells (REC) up to 15 days. The present results provide evidence of the occurrence, localization and post-hatching changes in Trk proteins in avian bursa of Fabricius. Trks were localized on non-lymphoid cells which participate in providing the adequate microenvironment for B lymphocyte maturation. Furthermore, the cell segregation in the expression of Trks suggests specific roles for their ligands in controlling the function of medullary SDC and REC, hence bursal lymphoid follicle physiology.

We present a characterization of the optical dynamics following photoexcitation in T 6 films. The relaxation of the excited state, generated by optical transitions at 3.2 eV, is measured using a time-resolved pump-probe technique. The relaxation kinetics consist of two main processes: a fast decay which depends on the excitation density and a slow decay which does not. We show that the fast dynamic is consistent with a time-dependent exciton annihilation model, which provides a value for the bimolecular rate constant of /2~ 3 × 10 −13 cm 3 s −1 2 . The slow decay is assigned to a monomolecular recombination process via exciton diffusion towards recombination centers. The obtained results are discussed within the wider context of photoexcitation in conducting polymers.

Through this work we wish to thoroughly study the “open” staircase which has been a recurrent pattern in Neapolitan architecture since the Renaissance, focusing essentially on minor architectures, to grasp to what extent famous examples and local construction traditions have influenced the architectural language. Some meaningful routes will be identified which can be traced back to different epochs of the construction and the enlargement of the city, and, for each element, the following points will be analysed in detail: reference typology, employed materials, employed construction methods, contemporary legislation, historical information on the building and/or the urban context, modifications suffered. From an operational point of view it will be compiled, for every analysed building, a card for to reassume the fundamental aspects above listed and, contemporarily, an accurate Archive research will be made for having further information on ancient normative, material employees, constructive customs and conception of the structures. To this first phase it will follow a second one concerning the typological/structural interpretation that will lead to define recovery directives of these interesting architectural forms. The structural interpretation will be articulated as a confrontation between the theoretical and practical knowledge of the time, starting from Neapolitan and non-Neapolitan treatises, and the modern numerical methods still in continual evolution.

In this paper, we study how to boost the performance of FDSOI (Fully-Depleted Silicon On Insulator) devices with High-K and Single Metal gate by using the combination of Ultra-Thin Buried Oxide (UTBOX), Ground Plane (GP) and local back biasing integrated with our hybrid process. The interest of local back biasing is highlighted in term of threshold voltage VT modulation and power management study on the 45 nm 0.374 μm2 bitcells and on the ESD functionality as compared to bulk technology.

Display Omitted The Ge impact on the threshold voltage (VT) and the flat band voltage (VFB) of SiGe pMOSFETs is evaluated through a comparison of experiments and simulations with various SiGe thicknesses and Ge contents. Increasing Ge content shifts linearly (VT-VFB) in full agreement with Poisson-Schrodinger simulation results accounting for adequate band discontinuity and strain. An additional VFB shift is needed to match the measured CV in accumulation, revealing a work function modification or the presence of dipole in the gate stack due to Ge diffusion.

For the first time, CMOS devices on UTBOX 25nm combined with strained SOI (sSOI) substrates have been demonstrated. A 20% Ion boost is highlighted with these substrates compared to the standard UTBB SOI ones. Performance up to 1530µA/µm @ Ioff=100nA/µm (Vd 1V) for a nominal Lg=30nm with a CET of 1.5nm for the NMOS has been achieved. The viability of this substrate has been demonstrated thanks to our hybrid process, through threshold voltage modulation and leakage current reduction, with back biasing for short devices. In addition, cell current improvement of 23% in 0.12µm2 bitcell is noticed for sSOI at the same stand-by current vs the standard UTBB SOI. Finally, the functionality of hybrid ESD device underneath the BOX is demonstrated.

This paper describes a study performed to evaluate inline metrology techniques for the monitoring of multiple SiGe layers in a manufacturing environment. Comparative measurements between High Resolution X-Ray Diffraction (HRXRD), X-Ray Reflectometry (XRR) and spectroscopic ellipsometry (SE) optical technique were carried out on a specifically-design wafer set. Strength and drawback of each technique are presented. An innovative approach of combining techniques for such application is explored and the results confirm the benefit of this strategy.

All these results show mainly the effectiveness of 45° rotated substrate enabling an increase of mobility performance for PMOS as compared to not rotated substrate. For NMOS devices, combined access resistance and mobility improvements explain the performance gain for rotated substrate.

In this paper, we compare the electrical properties of Ultra Thin Buried Oxide (UTBOX) Fully Depleted Silicon On Insulator (FD-SOI) MOS devices for rotated and not rotated substrate with different gate lengths. We found a significant performance enhancement on FD-SOI PMOSFETs as expected, while keeping a good control of short channel effects. Surprisingly, to a lower extent, an improvement is also found for NMOS devices. We have also studied the carrier mobility degradation as a function of temperature and we point out the contribution of different mechanisms that reduce the mobility such as impurity Coulomb scattering, phonons and neutral defects as a function gate length. We find that there is no significant effect of rotated substrate on the mobility degradation. All these results are discussed and possible explanations are also given.

Background: Adherence to Mediterranean diet has been shown to be associated with a better health and greater survival. The aim of the present study was to identify change-points in the relationship between food groups composing Mediterranean diet and overall mortality. Methods: The population of the Greek EPIC prospective cohort study (23,349 adult men and women in the Greek EPIC sample who had not previously been diagnosed as having cancer, coronary heart disease or diabetes mellitus at enrolment) was analysed. Segmented logistic regression analysis was conducted to examine the association between each of the food groups contributing to the Mediterranean diet score and overall mortality. Results: This analysis allowed the determination of the following change-points: among men: 1 change-point for vegetables, legumes, cereals, fish and seafood and dairy products and 2 change-points for fruit and nuts, meat and meat products and ethanol; among women: 1 change-point for legumes and fish and seafood and 2 change-points for the remaining food groups. These cut-off points were used to construct an 'a posteriori' score that may be better in capturing the health-promoting potential of the traditional Mediterranean diet. Conclusion: Identification of change-points in the relationship between components of the Mediterranean diet and mortality can be used to increase the discriminatory ability of a widely used Mediterranean diet score in relation to mortality. © Springer-Verlag 2011.

In this paper we explore the impact of the parasitic bipolar in undoped channel Ultra-Thin BOX (UTBOX) with and without Ground Plane (GP) on a 32 nm Fully-Depleted SOI (FDSOI) high-k/metal gate technology. The static parasitic bipolar latch occurs at a drain bias superior to the circuit operation alimentation. The several type of ground plane and forward or reverse back biasing do not modify significantly the bipolar breakdown voltage. The thicker EOT gate oxide is more sensible to parasitic bipolar breakdown. Finally, results have been reinforced by using calibrated TCAD simulation tool.

Thin film devices (FDSOI) are among the most promising candidates for next device generations due to their better immunity to short channel effects (SCE). In addition, the introduction of high-k and metal gate has greatly improved the MOSFETs performance by reducing the electrical oxide thickness (CET) and gate leakage current. However, if midgap metal gate is sufficient to provide a high symmetrical threshold voltage (V T ∼0.45V) for both NMOS and PMOS devices [1], still one major challenge is to provide V T modulation with an undoped channel in order to satisfy the low power (LP) circuit design requirements [2–5]. To overcome this issue, combining UTBOX substrate with ground plane (GP) has been proposed [2,5]. However this technique with midgap metal gate requires a FBB biasing in order to realize low V T that's implies a disruptive circuits design to avoid forward diode biasing in the substrate between the two opposite GP type beneath the BOX [6]. In order to introduce more V T modulation flexibilities and especially for LVT PMOS and HVT NMOS, aluminum Oxide (Al 2 O 3 ) inserted in TiN gate stack has been proposed for bulk devices [7–8] in a gate first process. The viability of this option is studied in this paper for FDSOI, for HfO 2 and HfSiON gate oxide, through transistors performance, reliability and variability analysis.

For the first time, Multi-V T UTBOX-FDSOI technology for low power applications is demonstrated. We highlight the effectiveness of back biasing for short devices in order to achieve I ON current improvement by 45% for LVT options at an I OFF current of 23nA/µm and a leakage reduction by 2 decades for the HVT one. In addition, fully functional 0.299um2 bitcells with 290mV SNM at 1.1V and Vb=0V operation were obtained. We also demonstrate on ring oscillators and 0.299µm2 SRAM bitcells the effectiveness (ΔV T versus V b ∼ 208mV/V) of the conventional bulk reverse and forward back biasing approaches to manage the circuit static power and the dynamic performances.

The objective of this paper is to present the successful co-integration of Logic Ultra-Thin Body and Box (UTBB) devices and bulk-Si I/O devices on the same chip. The UTBB transistors are integrated locally on a Bulk wafer with the Localized Silicon On Insulator (LSOI) process technology with HfO 2 /TiN gate stack for low power applications. I/O co-integrated Bulk devices have a thicker interfacial SiO 2 under the HfO 2 /TiN stack to be compatible with the I/O higher voltage. Both performances of logic UTBB and I/O bulk devices are presented.

This paper highlights the successful co-integration of Localized Silicon-On-Insulator (LSOI) devices and of bulk-Si I/O devices on the same chip. LSOI devices present good logic performances and very low mismatch values down to 1.2mV/µm. In addition, we show the backbiasing impact on LSOI SRAM bit-cells for stability improvement. This work also presents the co-integration of LSOI with bulk devices as a solution for the devices that are not compatible with thin-body technology. In particular, we demonstrate for the first time competitive bulk co-integrated ElectroStatic Discharge (ESD) protections.

In this paper, we present FD-SOI with High-K and Single Metal gate as a possible candidate for LP multimedia technology. Dual gate oxide co-integrated devices with EOT 17A/V dd 1.1V and 29A/V dd 1.8V are reported. The interest of Ultra-Thin Buried Oxide substrates (UTBOX) is reported in term of Multiple Vt achievement and matching improvement. Delay improvement up to 15% is reported on Ring Oscillators as compared to bulk 45nm devices. In addition, for the first time 99.998% 2Mbit 0.374µm2 SRAM cut functionality has been demonstrated. Thanks to a hybrid FDSOI/bulk co-integration with UTBOX all IP's required in a SOC are demonstrated for LP applications.