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14. Correlating Nanocrystalline Structure with Electronic Properties in 2D Platinum Diselenide

Author

Lukas, Sebastian, Hartwig, Oliver, Prechtl, Maximilian, Capraro, Giovanna, Bolten, Jens, Meledin, Alexander, Mayer, Joachim, Neumaier, Daniel, Kataria, Satender, Duesberg, Georg S., and Lemme, Max C.

Subjects
Condensed Matter - Materials Science, Physics - Applied Physics
Abstract

Platinum diselenide (PtSe${_2}$) is a two-dimensional (2D) material with outstanding electronic and piezoresistive properties. The material can be grown at low temperatures in a scalable manner which makes it extremely appealing for many potential electronics, photonics, and sensing applications. Here, we investigate the nanocrystalline structure of different PtSe${_2}$ thin films grown by thermally assisted conversion (TAC) and correlate them with their electronic and piezoresistive properties. We use scanning transmission electron microscopy for structural analysis, X-ray photoelectron spectroscopy (XPS) for chemical analysis, and Raman spectroscopy for phase identification. Electronic devices are fabricated using transferred PtSe${_2}$ films for electrical characterization and piezoresistive gauge factor measurements. The variations of crystallite size and their orientations are found to have a strong correlation with the electronic and piezoresistive properties of the films, especially the sheet resistivity and the effective charge carrier mobility. Our findings may pave the way for tuning and optimizing the properties of TAC-grown PtSe${_2}$ towards numerous applications.

Published
2021
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21. Electronic Structure Shift of Deep Nanoscale Silicon by SiO$_2$- vs. Si$_3$N$_4$-Embedding as Alternative to Impurity Doping

Author

König, Dirk, Wilck, Noël, Hiller, Daniel, Berghoff, Birger, Meledin, Alexander, Di Santo, Giovanni, Petaccia, Luca, Mayer, Joachim, Smith, Sean, and Knoch, Joachim

Subjects
Condensed Matter - Mesoscale and Nanoscale Physics
Abstract

Conventional impurity doping of deep nanoscale silicon (dns-Si) used in ultra large scale integration (ULSI) faces serious challenges below the 14 nm technology node. We report on a new fundamental effect in theory and experiment, namely the electronic structure of dns-Si experiencing energy offsets of ca. 1 eV as a function of SiO$_2$- vs. Si$_3$N$_4$-embedding with a few monolayers (MLs). An interface charge transfer (ICT) from dns-Si specific to the anion type of the dielectric is at the core of this effect and arguably nested in quantum-chemical properties of oxygen (O) and nitrogen (N) vs. Si. We investigate the size up to which this energy offset defines the electronic structure of dns-Si by density functional theory (DFT), considering interface orientation, embedding layer thickness, and approximants featuring two Si nanocrystals (NCs); one embedded in SiO$_2$ and the other in Si$_3$N$_4$. Working with synchrotron ultraviolet photoelectron spectroscopy (UPS), we use SiO$_2$- vs. Si$_3$N$_4$-embedded Si nanowells (NWells) to obtain their energy of the top valence band states. These results confirm our theoretical findings and gauge an analytic model for projecting maximum dns-Si sizes for NCs, nanowires (NWires) and NWells where the energy offset reaches full scale, yielding to a clear preference for electrons or holes as majority carriers in dns-Si. Our findings can replace impurity doping for n/p-type dns-Si as used in ultra-low power electronics and ULSI, eliminating dopant-related issues such as inelastic carrier scattering, thermal ionization, clustering, out-diffusion and defect generation. As far as majority carrier preference is concerned, the elimination of those issues effectively shifts the lower size limit of Si-based ULSI devices to the crystalization limit of Si of ca. 1.5 nm and enables them to work also under cryogenic conditions., Comment: 14 pages, 17 Figures with a total 44 graphs

Published
2019
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30. SEPIA - a new single pixel receiver at the APEX Telescope

Author

Belitsky, V., Lapkin, I., Fredrixon, M., Meledin, D., Sundin, E., Billade, B., Ferm, S. -E., Pavolotsky, A., Rashid, H., Strandberg, M., Desmaris, V., Ermakov, A., Krause, S., Olberg, M., Aghdam, P., Shafiee, S., Bergman, P., De Beck, E., Olofsson, H., Conway, J., De Breuck, C., Immer, K., Yagoubov, P., Montenegro-Montes, F. M., Torstensson, K., Pérez-Beaupuits, J. -P., Klein, T., Boland, W., Baryshev, A. M., Hesper, R., Barkhof, J., Adema, J., Bekema, M. E., and Koops, A.

Subjects
Astrophysics - Instrumentation and Methods for Astrophysics
Abstract

Context: We describe the new SEPIA (Swedish-ESO PI Instrument for APEX) receiver, which was designed and built by the Group for Advanced Receiver Development (GARD), at Onsala Space Observatory (OSO) in collaboration with ESO. It was installed and commissioned at the APEX telescope during 2015 with an ALMA Band 5 receiver channel and updated with a new frequency channel (ALMA Band 9) in February 2016. Aims: This manuscript aims to provide, for observers who use the SEPIA receiver, a reference in terms of the hardware description, optics and performance as well as the commissioning results. Methods: Out of three available receiver cartridge positions in SEPIA, the two current frequency channels, corresponding to ALMA Band 5, the RF band 158--211 GHz, and Band 9, the RF band 600--722 GHz, provide state-of-the-art dual polarization receivers. The Band 5 frequency channel uses 2SB SIS mixers with an average SSB noise temperature around 45K with IF (intermediate frequency) band 4--8 GHz for each sideband providing total 4x4 GHz IF band. The Band 9 frequency channel uses DSB SIS mixers with a noise temperature of 75--125K with IF band 4--12 GHz for each polarization. Results: Both current SEPIA receiver channels are available to all APEX observers., Comment: Accepted for publication in Astronomy & Astrophysics

Published
2017
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31. Development of phase doppler anemometry method with a measurement object in the form of a cylinder

Author

Kabardin Ivan, Meledin Vladimir, Dvoynishnikov Sergey, Rahmanov Vitaly, Pavlov Vladimir, and Zubanov Kirill

Subjects
Environmental sciences, GE1-350
Abstract

Developing methods for diagnosing particle sizes in an aerodynamic flow is a pressing issue in a number of technical applications such as engine building, power engineering, coating, and others. One of the methods for diagnosing particle sizes is the phase Doppler anemometry (PDA) method. It is a laser optical method for simultaneously measuring the speed and size of spherical particles. The purpose of this work is to test the performance of a method that implements phase Doppler anemometry to obtain the dependence of the phase shift on photodetectors on the diameters of the wires. The work presents a differential optical scheme of the installation with a helium-neon laser as a radiation source.

Published
2024
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39. Transthyretin cardiac amyloidosis in patients after TAVR: clinical and echocardiographic findings and long term survival

Author

Sara Shimoni, Meital Zikri, Dan Haberman, Shay Livschitz, Sagi Tshori, Yacov Fabricant, Valery Meledin, Gera Gandelman, Sorel Goland, and Jacob George

Subjects
Amyloidosis, Aortic valve intervention, Myocardial strain, Diseases of the circulatory (Cardiovascular) system, RC666-701
Abstract

Abstract Aims The aim of this study was to examine the prevalence of amyloid transthyretin (ATTR) cardiac amyloidosis in patients 1–2 years after trans‐catheter aortic valve replacement (TAVR) and to assess their clinical and echocardiographic outcome and long‐term survival. Methods and results We enrolled 88 patients, mean age 81 years, 534 (390–711) days after TAVR. Patients underwent a Tc99m‐PYP scintigraphy for the diagnosis of ATTR cardiac amyloidosis. Eleven (12.5%) participants were diagnosed with ATTR cardiac amyloidosis. Eighty eight per cent of patients without amyloidosis were in New York Heart Association Classes 1–2 after TAVR, compared with 64% patients with ATTR cardiac amyloidosis (P = 0.022). There were no differences in left ventricular (LV) ejection fraction (P = 0.69) between patients with and without ATTR cardiac amyloidosis at enrolment. The LV mass index and pulmonary artery pressure were significantly higher in patients with ATTR cardiac amyloidosis (P = 0.046 and P = 0.002, respectively). Global longitudinal strain and myocardial work efficiency were significantly lower in patients with ATTR cardiac amyloidosis (P = 0.031 and P = 0.048, respectively). We assessed changes in echocardiographic data, from the time of TAVR to enrolment, and as expected, there was a significant decrease in aortic valve gradient in both groups. There was a significant reduction in LV mass and LV mass index and improvement in basal segment LV strain in the ATTR cardiac amyloidosis negative group (P = 0.045, P = 0.046 and 0.023, respectively). However, in the ATTR cardiac amyloidosis group the change in LV mass and LV mass index and LV basal strain values was not significant (P = 0.24, P = 0.13 and P = 0.35, respectively). The were no significant changes in other echocardiographic parameters in both groups. The patients were followed for 1150 (1086–1221) days after enrolment. Twenty seven patients had at least one cardiac hospitalization during of follow up, of them seven were with ATTR cardiac amyloidosis and 20 patients without amyloidosis (P = 0.017). Eighteen patients (20%) died during follow up; 12 (14%) patients died due to cardiac causes. There was no difference in all‐cause and cardiac mortality between patients with and without ATTR cardiac amyloidosis (P = 0.6 and P = 0.53, respectively). Conclusions The long‐term survival after TAVR is not significantly affected by the presence of ATTR cardiac amyloidosis. However, the clinical course of these patients and the LV hemodynamic improvement is less favourable. This hypothesis‐generating study suggests screening for ATTR cardiac amyloidosis in patients who underwent TAVR and have limited clinical or echocardiographic improvement, because they may potentially improve with new therapies for ATTR cardiac amyolidosis.

Published
2021
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