Relatively low-temperature processing and its impact on device performance and reliability

Non-silicon, large-area/flexible electronics for the internet of things (IoT) has acquired substantial attention in recent years. Key electron devices to enable this technology include metal-oxide-semiconductor field effect transistors (MOSFETs), where ultra-thin and/or low-dimensional (i.e., 2D to a few layers) semiconductor materials may be required, like those found in thin-film transistors (TFTs) and transition metal dichalcogenide (TMD) FETs [1,2]. Whether TFT or TMDFET, a relatively low-temperature process commensurate with large-area/flex applications to enable large (i.e., greater than 300 mm) and/or flexible substrate fabrication is required. Furthermore, TMD materials may be implemented as the channel semiconductor to function as an ultra-thin body to mitigate short channel effects and extend further scaling as the future progresses in CMOS scaling. In addition, the gate dielectric insulator is another vital component of any MOSFET that requires investigation as part of the MOS stack in these types of transistors. Lastly, semiconductor materials mentioned herein do not have a universally accepted way to introduce dopants to form sources and drains. Thus, metal-semiconductor contacts are employed where the interface region of the contact plays a critical role in determining the conductivity/resistivity of the contact. Moreover, how the metal-semiconductor interface are formed also impacts the quality of the contact. Therefore, exploration of low-temperature processing, interfaces, and their impact on device performance and reliability will be critical to eventual implementation in future technologies. To ascertain the impact of low-temperature fabrication and critical interfaces, several process approaches and electrical characterization methods were employed [1-6]. In one case, for a TMD FET contact study, an oxygen plasma exposure in the contact region on MoS2 (a TMD material) is done prior to titanium deposition. The results demonstrate that contaminants and photoresist residue that still reside after development can noticeably impact electrical performance (Fig. 1). The O2 plasma removes the residue present at the surface of MoS2 without the use of a high temperature anneal, and subsequently improves the device performance significantly (Fig. 1) [1]. In another case, for a MOS-based TFT study, an investigation of low-temperature (\u3e 115°C) deposited zinc-based semiconductors was executed (Fig. 2). For ZnO and IGZO, saturation mobilities of 14.4 and 8.4 cm2/V-s, along with threshold voltages of 2.2 V and 2.0 V were obtained, respectively, demonstrating robust devices that also have an on/off ratio \u3e 108, with IOFF lower than 10-12 A. Furthermore, a hot carrier stress methodology demonstrated threshold voltage (VTH) shifts of 0.4 V and 1.8 V for ZnO and IGZO, respectively, after stress (Fig. 2) [2]. Continued research is required to ascertain the electrically active defects responsible for the VTH shift. Please click Additional Files below to see the full abstract

Adaptive Mobile Health Intervention for Adolescents with Asthma: Iterative User-Centered Development

Background: Adolescents diagnosed with persistent asthma commonly take less than 50% of their prescribed inhaled corticosteroids (ICS), placing them at risk for asthma-related morbidity. Adolescents’ difficulties with adherence occur in the context of normative developmental changes (eg, increased responsibility for disease management) and rely upon still developing self-regulation and problem-solving skills that are integral for asthma self-management. We developed an adaptive mobile health system, Responsive Asthma Care for Teens (ReACT), that facilitates self-regulation and problem-solving skills during times when adolescents’ objectively measured ICS adherence data indicate suboptimal rates of medication use. Objective: The current paper describes our user-centered and evidence-based design process in developing ReACT. We explain how we leveraged a combination of individual interviews, national crowdsourced feedback, and an advisory board comprised of target users to develop the intervention content. Methods: We developed ReACT over a 15-month period using one-on-one interviews with target ReACT users (n=20), national crowdsourcing (n=257), and an advisory board (n=4) to refine content. Participants included 13-17–year-olds with asthma and their caregivers. A total of 280 adolescents and their caregivers participated in at least one stage of ReACT development. Results: Consistent with self-regulation theory, adolescents identified a variety of salient intrapersonal (eg, forgetfulness, mood) and external (eg, changes in routine) barriers to ICS use during individual interviews. Adolescents viewed the majority of ReACT intervention content (514/555 messages, 93%) favorably during the crowdsourcing phase, and the advisory board helped to refine the content that did not receive favorable feedback during crowdsourcing. Additionally, the advisory board provided suggestions for improving additional components of ReACT (eg, videos, message flow). Conclusions: ReACT involved stakeholders via qualitative approaches and crowdsourcing throughout the creation and refinement of intervention content. The feedback we received from participants largely supported ReACT’s emphasis on providing adaptive and personalized intervention content to facilitate self-regulation and problem-solving skills, and the research team successfully completed the recommended refinements to the intervention content during the iterative development process

WSe_(2-x)Te_x alloys grown by molecular beam epitaxy

The growth of WSe(2-x)Tex alloys by molecular beam epitaxy has been demonstrated for the first time to investigate the phase transition from the semiconducting 2H phase to the semi-metallic 1T’ phase as a function of Te concentration. Up to 14% Te incorporation, stable alloys in the semiconducting 2H phase are achieved while above 79% Te incorporation, stable alloys in the semi-metallic 1T’ phase are obtained. Our results indicate the MBE-grown WSe(2-x)Tex alloys exhibit a miscibility gap from 14% to 79% Te concentrations at a growth temperature of 250 °C, a temperature compatible with direct vertical back-end-of-line integration. This miscibility gap results in phase separation of two different alloys, both with different composition and crystal structure. While the alloying of small Te concentrations does indeed result in a desired reduction of the semiconducting bandgap, the phase separation above 14% Te incorporation prohibits bandgap tuning for a wider range of applications. These results highlight the competing energies and kinetics associated with producing uniform WSe(2-x)Tex alloys

Impact of etch processes on the chemistry and surface states of the topological insulator Bi2Se3

The unique properties of topological insulators such as Bi2Se3 are intriguing for their potential implementation in novel device architectures for low power and defect-tolerant logic and memory devices. Recent improvements in the synthesis of Bi2Se3 have positioned researchers to fabricate new devices to probe the limits of these materials. The fabrication of such devices, of course, requires etching of the topological insulator, in addition to other materials including gate oxides and contacts which may impact the topologically protected surface states. In this paper, we study the impact of He+ sputtering and inductively coupled plasma Cl2 and SF6 reactive etch chemistries on the physical, chemical, and electronic properties of Bi2Se3. Chemical analysis by X-ray photoelectron spectroscopy tracks changes in the surface chemistry and Fermi level, showing preferential removal of Se that results in vacancy-induced n-type doping. Chlorine-based chemistry successfully etches Bi2Se3 but with residual Se–Se bonding and interstitial Cl species remaining after the etch. The Se vacancies and residuals can be removed with postetch anneals in a Se environment, repairing Bi2Se3 nearly to the as-grown condition. Critically, in each of these cases, angle-resolved photoemission spectroscopy (ARPES) reveals that the topologically protected surface states remain even after inducing significant surface disorder and chemical changes, demonstrating that topological insulators are quite promising for defect-tolerant electronics. Changes to the ARPES intensity and momentum broadening of the surface states are discussed. Fluorine-based etching aggressively reacts with the film resulting in a relatively thick insulating film of thermodynamically favored BiF3 on the surface, prohibiting the use of SF6-based etching in Bi2Se3 processing

Anti-DLL4 VNAR targeted nanoparticles for targeting of both tumour and tumour associated vasculature

Acknowledgements The authors acknowledge the Engineering and Physical Sciences Research Council (EPSRC) (S3802ASA) and the generous support of the Martin Family Foundation for funding the Ph.D. studentships of P. S. and A. L., respectively. This work was also partially funded through a US-Ireland R&D Partnership grant awarded by HSCNI (STL/5010/14), Medical Research Council UK (MC_PC_15013), and the Biotechnology and Biological Sciences Research Council (BBSRC) (BB/R009112/1).Peer reviewedPublisher PD

Responsive Asthma Care for Teens (ReACT): Development protocol for an adaptive mobile health intervention for adolescents with asthma

This work is licensed under a Creative Commons Attribution-NonCommercial 4.0 International License.Introduction Asthma is a leading cause of youth morbidity in the USA, affecting >8% of youth. Adherence to inhaled corticosteroids (ICS) can prevent asthma-related morbidity; however, the typical adolescent with asthma takes fewer than 50% of their prescribed doses. Adolescents are uniquely vulnerable to suboptimal asthma self-management due to still-developing executive functioning capabilities that may impede consistent self-regulation and weaken attempts to use problem solving to overcome barriers to ICS adherence. Methods and analysis The aims of this project are to improve adherence to ICS as an important step towards better self-management among adolescents aged 13–17 years diagnosed with asthma by merging the efficacious behaviour change strategies found in behavioural health interventions with scalable, adaptive mobile health (mHealth) technologies to create the Responsive Asthma Care for Teens programme (ReACT). ReACT intervention content will be developed through an iterative user-centred design process that includes conducting (1) one-on-one interviews with 20 teens with asthma; (2) crowdsourced feedback from a nationally representative panel of 100 adolescents with asthma and (3) an advisory board of youth with asthma, a paediatric pulmonologist and a behavioural health expert. In tandem, we will work with an existing technology vendor to programme ReACT algorithms to allow for tailored intervention delivery. We will conduct usability testing of an alpha version of ReACT with a sample of 20 target users to assess acceptability and usability of our mHealth intervention. Participants will complete a 4-week run-in period to monitor their adherence with all ReACT features turned off. Subsequently, participants will complete a 4-week intervention period with all ReACT features activated. The study started in October 2018 and is scheduled to conclude in late 2019. Ethics and dissemination Institutional review board approval was obtained at the University of Kansas and the University of Florida. We will submit study findings for presentation at national research conferences that are well attended by a mix of psychologists, allied health professionals and physicians. We will publish study findings in peer-reviewed journals read by members of the psychology, nursing and pulmonary communities

Optimising mechanical separation of anaerobic digestate for total solids and nutrient removal

Publication history: Accepted - 16 June 2023; Published - 28 June 2023.Mechanical separation of anaerobic digestate has been identified as a method to reduce pollution risk to waterways by partitioning phosphorus in the solid fraction and reducing its application to land. Separators have adjustable parameters which affect separation efficiency, and hence the degree of phosphorous partitioning, but information on how these parameters affect separation performance is limited in the literature. Two well known technologies were investigated, decanter centrifuge and screw press, to determine the most efficient method of separation. Counterweight load and the use of an oscillator were adjusted for the screw press, while bowl speed, auger differential speed, feed rate and polymer addition were modified for the decanter centrifuge. Separation efficiency was determined for total solids, phosphorus, nitrogen, potassium, and carbon, and the total solids content of resulting fractions was measured. The decanter centrifuge had higher separation efficiency for phosphorus in all cases, ranging from 51% to 71.5%, while the screw press had a phosphorus separation efficiency ranging from 8.5% to 10.9% for digestate of ~5% solids (slurry/grass silage mix). Separation by decanter centrifuge partitioned up to 56% of nitrogen in the solid fraction leaving a reduced nitrogen content in the liquid fraction available for land spreading; this nitrogen would most likely need to be replaced by chemical fertiliser which would add to the cost of the system. The decanter centrifuge is better suited to cases where phosphorus recovery is the most important factor, while the screw press could be advantageous in cases where cost is a limiting factor.This project was supported by The Bryden Centre. The Bryden Centre project is supported by the European Union’s INTERREG VA Programme, managed by the Special EU Programmes Body (SEUPB). The views and opinions expressed in this paper do not necessarily reflect those of the European Commission or the Special EU Programmes Body (SEUPB). The work was also supported by Queen’s University Belfast and the Agri-Food and Biosciences Institute in Northern Ireland

Early respiratory bacterial detection and anti-staphylococcal antibiotic prophylaxis in young children with cystic fibrosis

Rationale: Consensus is lacking regarding anti-staphylococcal antibiotic prophylaxis use for young children with cystic fibrosis. Prophylaxis is recommended in the UK, but recommended against in the US. Objectives: To test the hypothesis that anti-staphylococcal antibiotic prophylaxis is associated with a decreased risk of Staphylococcus aureus acquisition, but no increased risk of Pseudomonas aeruginosa acquisition. Methods: We undertook a longitudinal observational study of children with cystic fibrosis who were recruited from birth (or their first registry entry in the period) and followed until the age of 4 years (1500 days) using UK CF Trust and US CF Foundation Registries, 2000-2009. Children were excluded if they had a culture positive for S. aureus or P. aeruginosa, or were receiving inhaled antibiotics, at first encounter. Time to first S.aureus and P. aeruginosa detection in the UK/US cohorts were compared using a Cox proportional hazards model. A UK-based analysis compared the same for those receiving flucloxacillin with those who received no prophylaxis. We included the following covariates: sex, age at registry entry, Dornase alfa use, genotype and center size. Results: The primary analysis consisted 1074 UK and 3677 US children. The risk of first detection was greater in US compared to UK for S. aureus (hazard ratio (HR) 5.79; 95% CI: 4.85, 6.90; p<0.001) and P. aeruginosa (HR 1.92; 95% CI: 1.65, 2.24; p<0.001). The UK analysis compared 278 children receiving flucloxacillin and 306 receiving no prophylaxis. Flucloxacillin was not associated with a reduced risk of S. aureus (HR 1.22; 95% CI: 0.74, 2.0; p=0.43), but was associated with an increased risk of P. eruginosa (HR 2.53; 95% CI: 1.71, 3.74; p<0.001) detection. None of the covariates significantly affected the risk estimate in either analysis. Conclusions: Risk of first detection of S. aureus and P. aeruginosa is greater in US compared to UK. In the UK, the risk of first P. aeruginosa detection is increased among those receiving flucloxacillin compared to those who received no prophylaxis. These observational findings should be explored in a randomized controlled trial