Crystallization kinetics of nanoconfined GeTe slabs in GeTe/TiTe[Formula: see text]-like superlattices for phase change memories.

Superlattices made of alternating blocks of the phase change compound Sb[Formula: see text]Te[Formula: see text] and of TiTe[Formula: see text] confining layers have been recently proposed for applications in neuromorphic devices. The Sb[Formula: see text]Te[Formula: see text]/TiTe[Formula: see text] heterostructure allows for a better control of multiple intermediate resistance states and for a lower drift with time of the electrical resistance of the amorphous phase. However, Sb[Formula: see text]Te[Formula: see text] suffers from a low data retention due to a low crystallization temperature T[Formula: see text]. Substituting Sb[Formula: see text]Te[Formula: see text] with a phase change compound with a higher T[Formula: see text], such as GeTe, seems an interesting option in this respect. Nanoconfinement might, however, alters the crystallization kinetics with respect to the bulk. In this work, we investigated the crystallization process of GeTe nanoconfined in geometries mimicking GeTe/TiTe[Formula: see text] superlattices by means of molecular dynamics simulations with a machine learning potential. The simulations reveal that nanoconfinement induces a mild reduction in the crystal growth velocities which would not hinder the application of GeTe/TiTe[Formula: see text] heterostructures in neuromorphic devices with superior data retention.

Thick Does the Trick: Genesis of Ferroelectricity in 2D GeTe-Rich (GeTe)m (Sb2 Te3 )n Lamellae.

The possibility to engineer (GeTe)m (Sb2 Te3 )n phase-change materials to co-host ferroelectricity is extremely attractive. The combination of these functionalities holds great technological impact, potentially enabling the design of novel multifunctional devices. Here an experimental and theoretical study of epitaxial (GeTe)m (Sb2 Te3 )n with GeTe-rich composition is presented. These layered films feature a tunable distribution of (GeTe)m (Sb2 Te3 )1 blocks of different sizes. Breakthrough evidence of ferroelectric displacement in thick (GeTe)m (Sb2 Te3 )1 lamellae is provided. The density functional theory calculations suggest the formation of a tilted (GeTe)m slab sandwiched in GeTe-rich blocks. That is, the net ferroelectric polarization is confined almost in-plane, representing an unprecedented case between 2D and bulk ferroelectric materials. The ferroelectric behavior is confirmed by piezoresponse force microscopy and electroresistive measurements. The resilience of the quasi van der Waals character of the films, regardless of their composition, is also demonstrated. Hence, the material developed hereby gathers in a unique 2D platform the phase-change and ferroelectric switching properties, paving the way for the conception of innovative device architectures.

Risk Identification and Analysis in the Development of Medical Devices Among Start-Ups: Towards a Broader Risk Management Framework.

Introduction: Whilst risk management has become fundamental in the development of medical devices, enforced by regulations and international standards, there is still no comprehensive model that explains how risk management in medical devices' development should be tackled, especially with regard to the type of risks that should be addressed. Risk management in the medical devices' development field is currently focused on technical risks, comprising product, usability, and development process risks, in alignment with standards' requirements and regulations, without giving enough attention to non-technical risks, which include business and project risks. Start-ups within this heavily regulated domain have a key role in the innovation process, yet they suffer a structural lack of tangible, such as financial capacity, and intangible resources such as development, risk management, and regulations' compliance. Nonetheless, they can still optimize their risk identification coverage beyond the enforced requirements to increase their products' chances of success. Methods: A set of qualitative interviews, serving the adopted grounded theory building research method, with seven start-ups who are involved in the development, commercialization, and quality control of medical devices was accomplished. The purpose was to determine the applied risk management practices and most importantly identify the risk types covered by them. Since every start-up is a project by itself, a sample of project risks, as identified by the project management institute, was utilized to scope the risk coverage and flag missing non-technical risks by the participating start-ups. Results: Un-identified risk types, lack of involvement of the right teams, and other related loopholes were presented. Discussion: A list of requirements was developed and sketched in a user-friendly risk management framework, which is believed to be crucial in helping start-ups attain successful, safe, and regulatory compliant medical devices production, is shared in the discussion and proposed framework section of this paper.

Evaluating Filtering Facepiece Respirator Wearing-Comfort of Lebanese Red Cross Healthcare Providers.

Introduction: The COVID-19 pandemic significantly increased the usage of various types of face masks. In addition, it triggered the rapid manufacture of new production lines of masks to cope with the unprecedented demand to overcome worldwide shortages. Such masks, which were previously used mostly by the health care personnel, became a daily necessity to the greater mainstream population. This rapid and sudden increase in their usage and the fact that new masks' innovations are progressively emerging to meet the growing global shortage requires an ongoing analysis on the factors associated with the fit and comfort while using these masks. Methods: This paper presents the first translation and validation of the R-COMFI questionnaire to evaluate the comfort of a newly developed filtering face-piece respirator by the research team at the University of Antwerp. The questionnaire, which consists of 3 sections: Discomfort, General wearing experience, and Function, was translated from English to Arabic and involved 43 participants in the Lebanese Red Cross healthcare field based in Lebanon. Results: The results showed discomfort factors that are mostly related to breathability and sweating caused by mask usage. Additionally, the results revealed that female respondents found the mask significantly less comfortable than male respondents (p-value with the two-tailed test is 0.0319), which confirmed that future validations should consider the concerns of both genders, and validated the R-COMFI translation exercise detailed in this paper. Discussion: The contribution of this paper can be pinned down into three findings. The first finding is related to the discomfort issues. The second finding highlighted a significant difference in comfort experience between females and males. The last finding is the translation validation of the R-COMFI instrument, which confirmed that the questionnaire can be applied among wider geographical locations.

Phase Separation in Ge-Rich GeSbTe at Different Length Scales: Melt-Quenched Bulk versus Annealed Thin Films.

Integration of the prototypical GeSbTe (GST) ternary alloys, especially on the GeTe-Sb2Te3 tie-line, into non-volatile memory and nanophotonic devices is a relatively mature field of study. Nevertheless, the search for the next best active material with outstanding properties is still ongoing. This search is relatively crucial for embedded memory applications where the crystallization temperature of the active material has to be higher to surpass the soldering threshold. Increasing the Ge content in the GST alloys seems promising due to the associated higher crystallization temperatures. However, homogeneous Ge-rich GST in the as-deposited condition is thermodynamically unstable, and phase separation upon annealing is unavoidable. This phase separation reduces endurance and is detrimental in fully integrating the alloys into active memory devices. This work investigated the phase separation of Ge-rich GST alloys, specifically Ge5Sb2Te3 or GST523, into multiple (meta)stable phases at different length scales in melt-quenched bulk and annealed thin film. Electron microscopy-based techniques were used in our work for chemical mapping and elemental composition analysis to show the formation of multiple phases. Our results show the formation of alloys such as GST213 and GST324 in all length scales. Furthermore, the alloy compositions and the observed phase separation pathways agree to a large extent with theoretical results from density functional theory calculations.

Interface Formation during the Growth of Phase Change Material Heterostructures Based on Ge-Rich Ge-Sb-Te Alloys.

In this study, we present a full characterization of the electronic properties of phase change material (PCM) double-layered heterostructures deposited on silicon substrates. Thin films of amorphous Ge-rich Ge-Sb-Te (GGST) alloys were grown by physical vapor deposition on Sb2Te3 and on Ge2Sb2Te5 layers. The two heterostructures were characterized in situ by X-ray and ultraviolet photoemission spectroscopies (XPS and UPS) during the formation of the interface between the first and the second layer (top GGST film). The evolution of the composition across the heterostructure interface and information on interdiffusion were obtained. We found that, for both cases, the final composition of the GGST layer was close to Ge2SbTe2 (GST212), which is a thermodynamically favorable off-stoichiometry GeSbTe alloy in the Sb-GeTe pseudobinary of the ternary phase diagram. Density functional theory calculations allowed us to calculate the density of states for the valence band of the amorphous phase of GST212, which was in good agreement with the experimental valence bands measured in situ by UPS. The same heterostructures were characterized by X-ray diffraction as a function of the annealing temperature. Differences in the crystallization process are discussed on the basis of the photoemission results.

Crystallization and Electrical Properties of Ge-Rich GeSbTe Alloys.

Enrichment of GeSbTe alloys with germanium has been proposed as a valid approach to increase the crystallization temperature and therefore to address high-temperature applications of non-volatile phase change memories, such as embedded or automotive applications. However, the tendency of Ge-rich GeSbTe alloys to decompose with the segregation of pure Ge still calls for investigations on the basic mechanisms leading to element diffusion and compositional variations. With the purpose of identifying some possible routes to limit the Ge segregation, in this study, we investigate Ge-rich Sb2Te3 and Ge-rich Ge2Sb2Te5 with low (<40 at %) or high (>40 at %) amounts of Ge. The formation of the crystalline phases has been followed as a function of annealing temperature by X-ray diffraction. The temperature dependence of electrical properties has been evaluated by in situ resistance measurements upon annealing up to 300 °C. The segregation and decomposition processes have been studied by scanning transmission electron microscopy (STEM) and discussed on the basis of density functional theory calculations. Among the studied compositions, Ge-rich Ge2Sb2Te5 is found to be less prone to decompose with Ge segregation.

Efficient Quality Management in MedTech Start-Ups (Based on ISO 13485).

Start-ups that are involved in the development of medical devices play a key role in innovation, yet among the several limitations they encounter, they suffer a lack of knowledge in quality management. This lack may create a challenge that could hinder or limit their success. This paper seeks to present an overview and act as a guideline for the required documentation to establish a quality management system for start-ups in medical devices development, based on a case-studied start-up, in accordance with ISO 13485. Using this case study along with the actual ISO 13485 standard document, can support medical devices start-ups in their ISO compliance and certification journey.

High-Throughput Calculations on the Decomposition Reactions of Off-Stoichiometry GeSbTe Alloys for Embedded Memories.

Chalcogenide GeSbTe (GST) alloys are exploited as phase change materials in a variety of applications ranging from electronic non-volatile memories to neuromorphic and photonic devices. In most applications, the prototypical Ge2Sb2Te5 compound along the GeTe-Sb2Te3 pseudobinary line is used. Ge-rich GST alloys, off the pseudobinary tie-line with a crystallization temperature higher than that of Ge2Sb2Te5, are currently explored for embedded phase-change memories of interest for automotive applications. During crystallization, Ge-rich GST alloys undergo a phase separation into pure Ge and less Ge-rich alloys. The detailed mechanisms underlying this transformation are, however, largely unknown. In this work, we performed high-throughput calculations based on Density Functional Theory (DFT) to uncover the most favorable decomposition pathways of Ge-rich GST alloys. The knowledge of the DFT formation energy of all GST alloys in the central part of the Ge-Sb-Te ternary phase diagram allowed us to identify the cubic crystalline phases that are more likely to form during the crystallization of a generic GST alloy. This scheme is exemplified by drawing a decomposition map for alloys on the Ge-Ge1Sb2Te4 tie-line. A map of decomposition propensity is also constructed, which suggests a possible strategy to minimize phase separation by still keeping a high crystallization temperature.