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Ge1−xSnx thin films with a Sn content of x ≥ 0.1 present a direct bandgap, which is very interesting for the fabrication of efficient photonic devices. The monostanogermanide phase, Ni(GeSn), is promising to form ohmic contact in GeSn-based Si photonic devices. However, the formation kinetics of Ni stanogermanides and the incorporation of Sn in Ni–GeSn phases are not fully understood. In this work, Ni thin films were deposited on Ge and Ge0.9Sn0.1 layers grown in epitaxy on an Si(100) substrate using magnetron sputtering technique. In situ x-ray diffraction measurements were performed during the solid-state reaction of Ni/Ge and Ni/Ge0.9Sn0.1. 1D finite difference simulations based on the linear parabolic model were performed to determine the kinetics parameters for phase growth. The nucleation and growth kinetics of Ni germanides are modified by the addition of Sn. A delay in the formation of Ni(GeSn) was observed and is probably due to the stress relaxation in the Ni-rich phase. In addition, the thermal stability of the Ni(GeSn) phase is highly affected by Sn segregation. A model was developed to determine the kinetic parameters of Sn segregation in Ni(GeSn). [ABSTRACT FROM AUTHOR]

Ge-rich Ge2Sb2Te5 (GGST) is considered as one of the best candidates for industrial phase change memory production. GGST memory cells are generally embedded with Si or Ti nitride layers to prevent oxidation, as it leads to an undesired decrease of the GGST crystallization temperature. Furthermore, GGST films are usually doped with elements such as N, C, O, or Bi, aiming to delay GGST crystallization during the fabrication process as well as during memory cell operation. In this work, ultrahigh vacuum thermal desorption spectroscopy (TDS) was performed during isochronal annealing of a N-doped GGST film covered by a 10 nm-thick TiN x layer. Desorption is observed before GGST crystallization, but the comparison between TDS and in situ x-ray diffraction measurements shows that the main desorption peak, observed between 653 K and 703 K, occurs after GGST full crystallization. The most prominent desorbing species are Ar, N2, H2, and H. These results show that the TiN x polycrystalline layer cannot prevent N atoms from leaving the GGST layer during annealing, suggesting a progressive change of the N-doped GGST chemical composition during thermal annealing and crystallization. [ABSTRACT FROM AUTHOR]

Simulation of atomic redistribution in Geâ€"Sbâ€"Te (GST)-based memory cells during SET/RESET cycling is needed in order to understand GST memory cell failure and to design improved non-volatile memories. However, this type of atomic scale simulations is extremely challenging. In this work, we propose to use a simplified GST system in order to catch the basics of atomic redistribution in Ge-rich GST (GrGST) films using atomistic kinetic Monte Carlo simulations. Comparison between experiments and simulations shows good agreements regarding the influence of Ge excess on GrGST crystallization, as well as concerning the GST growth kinetic in GrGST films, suggesting the crystallized GST ternary compound to be off-stoichiometric. According to the simulation of atomic redistribution in GrGST films during SET/RESET cycling, the film microstructure stabilized during cycling is significantly dependent of the GST ternary phase stoichiometry. The use of amorphous layers exhibiting the GST ternary phase stoichiometry placed at the bottom or at the top of the GrGST layer is shown to be a way of controlling the microstructure evolution of the film during cycling. The significant evolution of the local composition in the amorphous solution during cycling suggests a non-negligible variation of the crystallization temperature with operation time. [ABSTRACT FROM AUTHOR]

Thermoelectricity is a well-known effect that can be used to convert heat energy into electrical energy. However, the yield of this conversion is still low compared to current photovoltaic technology. It is limited by the intrinsic properties of materials, leading to intensive materials science investigations for the design of efficient thermoelectric (TE) materials. Interface engineering was shown to be a valuable solution for improving materials' TE properties, supporting the development of multiphase TE materials. In particular, interfaces have been suggested to promote the increase of the Seebeck coefficient of materials without significantly impacting their electrical conductivity through the so-called energy filtering effect. This work aims at determining experimentally the effect of a metal/semiconductor interface exhibiting an ohmic character on the effective Seebeck coefficient of multiphase materials, focusing on the n-type Mn 5 Ge 3 /p-type Ge interface. This interface is shown not to contribute to carrier transport, but to contribute to carrier concentration filtering due to carrier injection or recombination. The Seebeck coefficient of the bi-phase material is shown to be dependent on the direction carriers are crossing the interface. The interface effect mainly results from a modification of charge carrier concentrations in the semiconductor., (© 2023. Springer Nature Limited.)

Ge-rich Ge 2 Sb 2 Te 5 (GGST) is considered as one of the best candidates for industrial phase change memory production. GGST memory cells are generally embedded with Si or Ti nitride layers to prevent oxidation, as it leads to an undesired decrease of the GGST crystallization temperature. Furthermore, GGST films are usually doped with elements such as N, C, O, or Bi, aiming to delay GGST crystallization during the fabrication process as well as during memory cell operation. In this work, ultrahigh vacuum thermal desorption spectroscopy (TDS) was performed during isochronal annealing of a N-doped GGST film covered by a 10 nm-thick TiN x layer. Desorption is observed before GGST crystallization, but the comparison between TDS and in situ x-ray diffraction measurements shows that the main desorption peak, observed between 653 K and 703 K, occurs after GGST full crystallization. The most prominent desorbing species are Ar, N 2 , H 2 , and H. These results show that the TiN x polycrystalline layer cannot prevent N atoms from leaving the GGST layer during annealing, suggesting a progressive change of the N-doped GGST chemical composition during thermal annealing and crystallization., (© 2023 IOP Publishing Ltd.)

Magnetic materials may be engineered to produce thermoelectric materials using spin-related effects. However, clear understanding of localized magnetic moments (µ I ), free carriers, and Seebeck coefficient (S) interrelations is mandatory for efficient material design. In this work, we investigate µ I influence on the spin-dependent S of model ferromagnetic thin films, allowing µ I thermal fluctuations, ordering, and density variation influence to be independently investigated. µ I influence on free carrier polarization is found to be of highest importance on S: efficient coupling of free carrier spin and localized magnetic moment promotes the increase of S, while spin-dependent relaxation time difference between the two spin-dependent conduction channels leads to S decrease. Our observations support new routes for thermoelectric material design based on spin-related effects in ferromagnetic materials., (© 2022. The Author(s).)

In this work a novel process allowing for the production of nanoporous Ge thin films is presented. This process uses the combination of two techniques: Ge sputtering on SiO2 and dopant ion implantation. The process entails four successive steps: (i) Ge sputtering on SiO2, (ii) implantation preannealing, (iii) high-dose dopant implantation, and (iv) implantation postannealing. Scanning electron microscopy and transmission electron microscopy were used to characterize the morphology of the Ge film at different process steps under different postannealing conditions. For the same postannealing conditions, the Ge film topology was shown to be similar for different implantation doses and different dopants. However, the film topology can be controlled by adjusting the postannealing conditions.

Noninvasive diagnosis of axillary and subclavian venous thrombosis or documentation of the post-thrombotic syndrome using modalities currently in use is not definitive. Light reflection rheography, which is a reflection of venous pressure changes in the extremity as recorded from the subdermal capillary plexus, was used to correctly diagnose axillary or subclavian venous thrombosis in 11 patients. A positive study was confirmed by phlebography in each instance. There were no instances of false-positive results. The methodology is simple, involving testing of the venous outflow from the upper extremity in response to exercise, application of venous congesting pressure, and measurement of the rate of venous outflow when the congesting pressure is released. Normal respiratory variations of an open venous system are also assessed by this noninvasive modality. The tracing obtained is easy to interpret and provides objective evidence of proximal venous occlusion. The test is not operator-dependent and the instrumentation is relatively inexpensive. We believe that light reflection rheography may be an exciting development in the noninvasive diagnosis of axillary or subclavian venous compromise and merits further trials.

A cytogenetic analysis of a fresh primary tumor specimen of small cell lung cancer showed a del(3)(p14p23) in the majority of metaphases. Additional clonal changes were found in the karyotype. No abnormalities for Ha-ras, Ki-ras, N-ras, myb, or myc were detected by Southern blot analysis of the tumor DNA.

It has been demonstrated, studying in retrospect a great number of urographies, that the most reliable urogram is the 5 minute urogram (5-U) after the end of the infusion of ionic contrast medium. The authors therefore, in order to save costs and dose to the population, suggest to simplify the urographical routine examination executing only 5-U. This is suggested especially in urographical evaluation of urolithiasis, urinary tract infections, prostate pathology, pelvic masses, pathologies in which 5-U is highly reliable. Very important is the immediate evaluation of 5-U, that allows to complete the urographical examination when necessary.

The authors report the results of a multicentric experience based on 1200 urograms performed with nonionic contrast medium. The global diagnostic reliability is evaluated, together with the specific reliability for kidneys, ureters, and bladder, according to the various pathologies. The eventual need of radiographs of completion is showed. In searching for an optimization of the technique for nonionic contrast medium, a panoramic radiograph performed 10' after the end of the injection is pointed out as the key-moment of the test, being extremely rich in information, so as to help defining the most appropriate technique to continue the examination. For its excellent tolerability and high reliability, the nonionic contrast medium is recommended also in routine IVP, not only in risk patients.