The role of vacancy dynamics in two-dimensional memristive devices. - In: Advanced electronic materials, ISSN 2199-160X, Bd. 10 (2024), 1, 2300635, S. 1-18
Two-dimensional layered transition metal dichalcogenides (TMDCs) are promising memristive materials for neuromorphic computing systems. Despite extensive experimental work, the underlying switching mechanisms are still not understood, impeding progress in material and device functionality. This study reveals the dominant role of defect dynamics in the switching process of 2D TMDC materials. The switching process is governed by the formation and annihilation dynamics of a local vacancy depletion zone. It explains the distinct features of the device characteristics observed experimentally, including fundamentally different device behavior previously thought to originate from multiple mechanisms. Key influence factors are identified and discussed with a fully coupled and dynamic charge transport model for electrons, holes, and ionic point defects, including image-charge-induced Schottky barrier lowering (SBL). Thermal effects and local Joule heating are considered by coupling the transient heat transfer equation to the electronic properties. The model is validated with hysteresis and pulse measurements for various lateral 2D MoS2-based devices, strongly corroborating the relevance of vacancy dynamics in TMDC devices and offering a new perspective on the switching mechanisms. The insights gained from this study can be used to extend the functional behavior of 2D TMDC memristive devices in future neuromorphic computing applications.
https://doi.org/10.1002/aelm.202300635
A universal design strategy based on NiPS3 nanosheets towards efficient photothermal conversion and solar desalination. - In: Advanced functional materials, ISSN 1616-3028, Bd. 34 (2024), 8, 2310942, S. 1-11
2D nanomaterials are proposed as promising photothermal materials for interfacial photothermal water evaporation. However, low evaporation efficiency, the use of hazardous hydrofluoric solution, and poor stability severely limit their practical applications. Here, a mixed solvent exfoliation surface deposition (MSESD) strategy for the preparation of NiPS3 nanosheets and NiPS3/polyvinyl alcohol (PVA) converter is successfully developed. The converter is obtained by drop-casting the NiPS3/PVA nanosheets onto a sponge. The PVA is mainly deposited on the edge of NiPS3 nanosheets, which not only improves the stability of NiPS3 nanosheets, but also adheres to the sponge to prepare a 3D photothermal converter, which shows an evaporation rate of 1.48 kg m−2 h−1 and the average photothermal conversion efficiency (PTCE) of 93.5% under a light intensity of 1 kW m−2. The photothermal conversion mechanism reveals that the energy of absorbed photons in NiPS3 nanosheets can be effectively converted into heat through non-radiative photon transitions as well as multiple optical interactions. To the best of the knowledge, this is the first report on the application of 2D metal-phosphorus-chalcogen (MPChx) for solar desalination, which provides new insights and guidance for the development of high-performance 2D photothermal materials.
https://doi.org/10.1002/adfm.202310942
Exploring the surface oxidation and environmental instability of 2H-/1T’-MoTe2 using field emission based scanning probe lithography. - In: Advanced materials, ISSN 1521-4095, Bd. 36 (2024), 4, 2310887, S. 1-14
An unconventional approach for the resistless nanopatterning 2H- and 1T’-MoTe2 by means of scanning probe lithography is presented. A Fowler-Nordheim tunneling current of low energetic electrons (E = 30-60 eV) emitted from the tip of an atomic force microscopy (AFM) cantilever is utilized to induce a nanoscale oxidation on a MoTe2 nanosheet surface under ambient conditions. Due to the water solubility of the generated oxide, a direct pattern transfer into the MoTe2 surface can be achieved by a simple immersion of the sample in deionized water. The tip-grown oxide was characterized using Auger electron and Raman spectroscopy, revealing it consists of amorphous MoO3/MoOx as well as TeO2/TeOx. With the presented technology in combination with subsequent AFM imaging it was possible to demonstrate a strong anisotropic sensitivity of 1T’-/(Td)-MoTe2 to aqueous environments. We finally used the discussed approach to structure a nanoribbon field effect transistor out of a few-layer 2H-MoTe2 nanosheet. This article is protected by copyright. All rights reserved
https://doi.org/10.1002/adma.202310887
Influence of the reference surface and AFM tip on the radius and roundness measurement of micro spheres. - In: Measurement science and technology, ISSN 1361-6501, Bd. 35 (2024), 2, 025010, S. 1-16
The performance of tactile and optical surface sensors for nano and micro coordinate measuring machines is currently limited by the lack of precisely characterised micro spheres, since established strategies have mainly been developed for spheres in the range of millimetres or above. We have, therefore, recently focused our research efforts towards a novel strategy for the characterisation of spheres in the sub-millimetre range. It is based on a set of atomic force microscope (AFM) surface scans in conjunction with a stitching algorithm. To obtain an uncertainty statement, the uncertainty about the shape of the reference surface needs to be propagated via the shape of the AFM tip to the actual measurement object. However, the sampling process of an AFM is non-linear and the processing of AFM scans requires complex algorithms. We have, therefore, recently begun to model the characterisation of micro spheres through simulations. In this contribution, this model is extended by the influence of the tip and reference surface. The influence of the tip’s shape and reference surface is investigated through virtual and real experiments. The shape of the tip is varied by using tips with mean radii of 200 nm and 2 μm while sampling the same ruby sphere with a mean radius of 150 μm. In general, the simulation results imply that an uncertainty of less then 10 nm is achievable. However, an experimental validation of the model is still pending. The experimental investigations were limited by the lack of a suitable cleaning strategy for micro parts, which demonstrates the need for further investigations in this area. Although the characterisation of a full sphere has already been demonstrated, the investigations in this contribution are limited to equator measurements.
https://doi.org/10.1088/1361-6501/ad03b7
High-resolution patterning on LTCC by transfer of photolithography-based metallic microstructures. - In: International journal of applied ceramic technology, ISSN 1744-7402, Bd. 21 (2024), 2, S. 1180-1190
The growing applications and constant miniaturization of electronic devices and of low-temperature co-fired ceramics (LTCC) in various fields, such as aviation, telecommunications, automotive, satellite communications, and military, have led to an increase in the demand for LTCC. Such prospects arise due to the continuous scaling down of components and high-density interconnection in electronics packaging. This paper reports a technique for the transfer of high-resolution microstructures from silicon substrates to LTCC. In this method, gold and copper patterns were formed by photolithography, electrodeposition, and residual layer stripping on silicon substrate. Lithography provides the opportunity to create and transfer complex patterns for use in several different applications and electroplating enables the use of pure metal for excellent electrical properties. The developed structures were transferred onto a top layer of LTCC tape using hot embossing. Then, the subsequent layers were stacked, laminated, and sintered. A resolution of 1.5 μm after free sintering and 4.5 μm after pressure-assisted sintering was achieved. This distinctive method can be useful for several applications requiring high-resolution and superior electrical properties.
https://doi.org/10.1111/ijac.14569
Parental sex education and sexual risk behavior of daughters and sons: findings from the representative survey “Youth Sexuality” :
Elterliche Sexualaufklärung und sexuelles Risikoverhalten bei Töchtern und Söhnen: Befunde aus der Repräsentativbefragung „Jugendsexualität“. - In: Bundesgesundheitsblatt, Gesundheitsforschung, Gesundheitsschutz, ISSN 1437-1588, Bd. 67 (2024), 1, S. 14-22
Hintergrund - Sexualaufklärung im Elternhaus soll laut Sozialisationstheorie zu mehr sexueller Handlungskompetenz bei Jugendlichen führen. Aktuelle Daten für Deutschland fehlen jedoch. Ziel der Arbeit - Vor diesem Hintergrund war es Ziel der vorliegenden Studie, erstmals das allgemeine Sprechen über Sexualität im Elternhaus (Forschungsfrage 1, F1) sowie speziell die Verhütungsberatung durch die Eltern (F2) mit dem sexuellen Risikoverhalten der Jugendlichen in Verbindung zu setzen. Material und Methoden - Datengrundlage ist die 9. Welle der Repräsentativbefragung „Jugendsexualität“ der Bundeszentrale für gesundheitliche Aufklärung (BZgA). Analysiert wurden Daten aller sexuell aktiven 14- bis 17-jährigen Jugendlichen im Sample, von denen eigene Angaben zum Sexualverhalten sowie Angaben ihrer Eltern zum Aufklärungsverhalten vorliegen (N= 357). Zur Beantwortung der beiden Forschungsfragen wurden logistische Regressionsanalysen mit 4 zentralen Merkmalen des jugendlichen Sexualverhaltens gerechnet. Ergebnisse - Es zeigte sich, dass das Sprechen über Sexualität im Elternhaus bei Mädchen und Jungen positiv korreliert mit 1. dem erreichten Konsensalter beim ersten Geschlechtsverkehr, 2. einem positiven Erleben des ersten Geschlechtsverkehrs, 3. einem zuverlässigen Verhütungsverhalten und 4. einer geringen Anzahl an Sexualpartner*innen (F1). Das gleiche Ergebnismuster ergab sich für die Verhütungsberatung durch die Eltern (F2). Diskussion - Die positiven Zusammenhänge zwischen elterlicher Sexualaufklärung und risikoärmerem jugendlichen Sexualverhalten gilt es hinsichtlich der zugrunde liegenden Kausalmechanismen genauer zu untersuchen.
https://doi.org/10.1007/s00103-023-03783-4
Assessing the utility of text-to-SQL approaches for satisfying software developer information needs. - In: Empirical software engineering, ISSN 1573-7616, Bd. 29 (2024), 1, 15, S. 1-48
Software analytics integrated with complex databases can deliver project intelligence into the hands of software engineering (SE) experts for satisfying their information needs. A new and promising machine learning technique known as text-to-SQL automatically extracts information for users of complex databases without the need to fully understand the database structure nor the accompanying query language. Users pose their request as so-called natural language utterance, i.e., question. Our goal was evaluating the performance and applicability of text-to-SQL approaches on data derived from tools typically used in the workflow of software engineers for satisfying their information needs. We carefully selected and discussed five seminal as well as state-of-the-art text-to-SQL approaches and conducted a comparative assessment using the large-scale, cross-domain Spider dataset and the SE domain-specific SEOSS-Queries dataset. Furthermore, we study via a survey how SE professionals perform in satisfying their information needs and how they perceive text-to-SQL approaches. For the best performing approach, we observe a high accuracy of 94% in query prediction when training specifically on SE data. This accuracy is almost independent of the query’s complexity. At the same time, we observe that SE professionals have substantial deficits in satisfying their information needs directly via SQL queries. Furthermore, SE professionals are open for utilizing text-to-SQL approaches in their daily work, considering them less time-consuming and helpful. We conclude that state-of-the-art text-to-SQL approaches are applicable in SE practice for day-to-day information needs.
https://doi.org/10.1007/s10664-023-10374-z
The framing of diversity statements in European universities: the role of imprinting and institutional legacy. - In: Minerva, ISSN 1573-1871, Bd. 62 (2024), 1, S. 69-92
We analyze the role of institutional founding conditions and institutional legacy for universities’ self-representation in terms of diversity. Based on 374 universities located in the Czech Republic, France, Germany, Hungary, Italy, and Poland, we can differentiate between a more idealistic understanding (logic of inclusion and equality) and a more market-oriented understanding (market logic) of diversity. Our findings show that the founding phase has no significant effect on the likelihood of a university focusing on a market-oriented understanding of diversity - however, we observe an imprinting effect with respect to the adoption of a diversity statement in general and an equity-oriented statement. Moreover, our findings show that there is a socialistic heritage for universities in Central and Eastern European (CEE) countries that is at work and still influences universities’ understandings of diversity today.
https://doi.org/10.1007/s11024-023-09507-x
Towards augmented and mixed reality on future mobile networks. - In: Multimedia tools and applications, ISSN 1573-7721, Bd. 83 (2024), 3, S. 9067-9102
Augmented and Mixed Reality (AR/MR) technologies enhance the human perception of the world by combining virtual and real environments. With the increase of mobile devices and the advent of 5G, this technology has the potential to become part of people’s life. This article aims to evaluate the impact of 5G and beyond mobile networks in the future of AR/MR. To attend to this objective, we surveyed four digital libraries to identify articles and reviews concerning AR/MR use based on mobile networks. The results describe the state-of-the-art of mobile AR/MR applications and the benefits and challenges of the technology. Finally, after the review, we propose a roadmap concerning AR/MR hardware and software development to run applications supported by future mobile networks.
https://doi.org/10.1007/s11042-023-15301-4
Digital media in intergenerational communication: status quo and future scenarios for the grandparent-grandchild relationship. - In: Universal access in the information society, ISSN 1615-5297, Bd. 23 (2024), 1, S. 379-394
Communication technologies play an important role in maintaining the grandparent-grandchild (GP-GC) relationship. Based on Media Richness Theory, this study investigates the frequency of use (RQ1) and perceived quality (RQ2) of established media as well as the potential use of selected innovative media (RQ3) in GP-GC relationships with a particular focus on digital media. A cross-sectional online survey and vignette experiment were conducted in February 2021 among N = 286 university students in Germany (mean age 23 years, 57% female) who reported on the direct and mediated communication with their grandparents. In addition to face-to-face interactions, non-digital and digital established media (such as telephone, texting, video conferencing) and innovative digital media, namely augmented reality (AR)-based and social robot-based communication technologies, were covered. Face-to-face and phone communication occurred most frequently in GP-GC relationships: 85% of participants reported them taking place at least a few times per year (RQ1). Non-digital established media were associated with higher perceived communication quality than digital established media (RQ2). Innovative digital media received less favorable quality evaluations than established media. Participants expressed doubts regarding the technology competence of their grandparents, but still met innovative media with high expectations regarding improved communication quality (RQ3). Richer media, such as video conferencing or AR, do not automatically lead to better perceived communication quality, while leaner media, such as letters or text messages, can provide rich communication experiences. More research is needed to fully understand and systematically improve the utility, usability, and joy of use of different digital communication technologies employed in GP-GC relationships.
https://doi.org/10.1007/s10209-022-00957-w