3 research outputs found
Ultrathin AlScN for low-voltage driven ferroelectric-based devices
Thickness scaling of ferroelectricity in AlScN is a determining factor for
its potential application in neuromorphic computing and memory devices. In this
letter, we report on ultrathin (10 nm) Al0.72Sc0.28N films that are
ferroelectrically switchable at room temperature. All-epitaxial
Al0.72Sc0.28N/Pt heterostructures are grown by magnetron sputtering onto
GaN/sapphire substrates followed by an in situ Pt capping approach to avoid
oxidation of the Al0.72Sc0.28N film surface. Structural characterization by
X-ray diffraction and transmission electron microscopy reveals the established
epitaxy. The thus obtained high-quality interfaces in combination with the in
situ capping is expected to facilitate ferroelectric switching of AlScN in the
ultrathin regime. The analysis of the relative permittivity and coercive field
dependence on the Al0.72Sc0.28N film thicknesses in the range of 100 nm down to
10 nm indicates only moderate scaling effects, suggesting that the critical
thickness for ferroelectricity is not yet approached. Furthermore, the
deposited layer stack demonstrates the possibility of including ultrathin
ferroelectric AlScN into all-epitaxial GaN-based devices using sputter
deposition techniques. Thus, our work highlights the integration and scaling
potential of all-epitaxial ultrathin AlScN offering high storage density paired
with low voltage operation desired for state of the art ferroelectric memory
devices
InâGrain Ferroelectric Switching in Subâ5 nm Thin Al0.74Sc0.26NÂ Films at 1 V
Abstract Analog switching in ferroelectric devices promises neuromorphic computing with the highest energy efficiency if limited device scalability can be overcome. To contribute to a solution, one reports on the ferroelectric switching characteristics of subâ5 nm thin Al0.74Sc0.26N films grown on Pt/Ti/SiO2/Si and epitaxial Pt/GaN/sapphire templates by sputterâdeposition. In this context, the study focuses on the following major achievements compared to previously available wurtziteâtype ferroelectrics: 1) Record low switching voltages down to 1 V are achieved, which is in a range that can be supplied by standard onâchip voltage sources. 2) Compared to the previously investigated deposition of ultrathin Al1âxScxN films on epitaxial templates, a significantly larger coercive field (Ec) to breakdown field ratio is observed for Al0.74Sc0.26N films grown on silicon substrates, the technologically most relevant substrateâtype. 3) The formation of true ferroelectric domains in wurtziteâtype materials is for the first time demonstrated on the atomic scale by scanning transmission electron microscopy (STEM) investigations of a subâ5 nm thin partially switched film. The direct observation of inversion domain boundaries (IDB) within single nmâsized grains supports the theory of a gradual domainâwall driven switching process in wurtziteâtype ferroelectrics. Ultimately, this should enable the analog switching necessary for mimicking neuromorphic concepts also in highly scaled devices
Swiss-wide multicentre evaluation and prediction of core outcomes in arthroscopic rotator cuff repair: protocol for the ARCR_Pred cohort study
Introduction In the field of arthroscopic rotator cuff repair (ARCR), reporting standards of published studies differ dramatically, notably concerning adverse events (AEs). In addition, prognostic studies are overall methodologically poor, based on small data sets and explore only limited numbers of influencing factors. We aim to develop prognostic models for individual ARCR patients, primarily for the patient-reported assessment of shoulder function (Oxford Shoulder Score (OSS)) and the occurrence of shoulder stiffness 6 months after surgery. We also aim to evaluate the use of a consensus core event set (CES) for AEs and validate a severity classification for these events, considering the patientâs perspective.Methods and analysis A cohort of 970 primary ARCR patients will be prospectively documented from several Swiss and German orthopaedic clinics up to 24 months postoperatively. Patient clinical examinations at 6 and 12 months will include shoulder range of motion and strength (Constant Score). Tendon repair integrity status will be assessed by ultrasound at 12 months. Patient-reported questionnaires at 6, 12 and 24 months will determine functional scores (subjective shoulder value, OSS), anxiety and depression scores, working status, sports activities, and quality of life (European Quality of Life 5 Dimensions 5 Level questionnaire). AEs will be documented according to a CES. Prognostic models will be developed using an internationally supported regression methodology. Multiple prognostic factors, including patient baseline demographics, psychological, socioeconomic and clinical factors, rotator cuff integrity, concomitant local findings, and (post)operative management factors, will be investigated.Ethics and dissemination This project contributes to the development of personalised risk predictions for supporting the surgical decision process in ARCR. The consensus CES may become an international reference for the reporting of complications in clinical studies and registries. Ethical approval was obtained on 1 April 2020 from the lead ethics committee (EKNZ, Basel, Switzerland; ID: 2019-02076). All participants will provide informed written consent before enrolment in the study.Trial registration number NCT04321005.Protocol version Version 2 (13 December 2019)