Trapping Layers Prevent Dopant Segregation and Enable Remote Doping of Templated Self-Assembled InGaAs Nanowires.

Selective area epitaxy is a promising approach to define nanowire networks for topological quantum computing. However, it is challenging to concurrently engineer nanowire morphology, for carrier confinement, and precision doping, to tune carrier density. We report a strategy to promote Si dopant incorporation and suppress dopant diffusion in remote doped InGaAs nanowires templated by GaAs nanomembrane networks. Growth of a dilute AlGaAs layer following doping of the GaAs nanomembrane induces incorporation of Si that otherwise segregates to the growth surface, enabling precise control of the spacing between the Si donors and the undoped InGaAs channel; a simple model captures the influence of Al on the Si incorporation rate. Finite element modeling confirms that a high electron density is produced in the channel.

What Should Personalised Mental Health Support Involve? Views of Young People with Lived Experience and Professionals from Eight Countries.

Research demonstrates that young people value mental health support that is tailored to their needs and preferences, rather than a "one size fits all" offer, which is often not equitably accessible (National Children's Bureau, 2021). Understanding young people's lived experiences across different sociocultural contexts is important. The aim of this research was to conduct an international qualitative study on the views of young people with lived experience and professionals, on proposed aspects of personalised support for anxiety and/or depression. Participatory action focus groups were conducted with N = 120 young people with lived experience of anxiety and/or depression (14-24 years) and with N = 63 professionals in Brazil, India, Kenya, Pakistan, Portugal, South Africa, Turkey, and the United Kingdom. Data were analysed using the rigorous and accelerated data reduction (RADaR) technique. Overall, although some country-specific differences were found in terms of what aspects of support young people found to be most important, individual preferences were considered stronger, furthering the view that support should be personalised to the needs of the individual young person. Young people experiencing anxiety and/or depression should be able to choose for themselves which aspects of support they would prefer in their own care and support plans, with families and mental health professionals providing guidance where appropriate, rather than removing the young person from the decision-making process altogether. It should also be ensured that the aspects of personalised support can be understood by young people and professionals from different contexts, including marginalised and minoritised groups and communities.

The implementation of thermal and UV nanoimprint lithography for selective area epitaxy.

Semiconductor nanowires (NWs) in horizontal configuration could provide a path for scalable NW-based devices. Bottom-up large-scale manufacturing of these nanostructures by selective area epitaxy (SAE) relies on precise nanopatterning of various shapes on the growth masks. Electron beam lithography offers an extraordinary accuracy suited for the purpose. However, this technique is not economically viable for large production as it has a low throughput and requires high investment and operational costs. Nanoimprint lithography (NIL) has the potential to reduce fabrication time and costs significantly while requiring less sophisticated equipment. In this work, we utilize both thermal and UV NIL for patterning substrates for SAE, elucidating the advantages and disadvantages of each lithography technique. We demonstrate the epitaxial growth of Ge and GaAs NWs on these substrates, where we observe high-quality mono-crystalline structures. Even though both processes can produce small uniform structures suitable for SAE, our results show that UV NIL proves to be superior and enables reliable and efficient patterning of sub-100 nm mask features at the wafer scale.

Coherent Hole Transport in Selective Area Grown Ge Nanowire Networks.

Holes in germanium nanowires have emerged as a realistic platform for quantum computing based on spin qubit logic. On top of the large spin-orbit coupling that allows fast qubit operation, nanowire geometry and orientation can be tuned to cancel out charge noise and hyperfine interaction. Here, we demonstrate a scalable approach to synthesize and organize Ge nanowires on silicon (100)-oriented substrates. Germanium nanowire networks are obtained by selectively growing on nanopatterned slits in a metalorganic vapor phase epitaxy system. Low-temperature electronic transport measurements are performed on nanowire Hall bar devices revealing high hole doping of ∼1018 cm-3 and mean free path of ∼10 nm. Quantum diffusive transport phenomena, universal conductance fluctuations, and weak antilocalization are revealed through magneto transport measurements yielding a coherence and a spin-orbit length of the order of 100 and 10 nm, respectively.

Selective area epitaxy of GaAs: the unintuitive role of feature size and pitch.

Selective area epitaxy (SAE) provides the path for scalable fabrication of semiconductor nanostructures in a device-compatible configuration. In the current paradigm, SAE is understood as localized epitaxy, and is modelled by combining planar and self-assembled nanowire growth mechanisms. Here we use GaAs SAE as a model system to provide a different perspective. First, we provide evidence of the significant impact of the annealing stage in the calculation of the growth rates. Then, by elucidating the effect of geometrical constraints on the growth of the semiconductor crystal, we demonstrate the role of adatom desorption and resorption beyond the direct-impingement and diffusion-limited regime. Our theoretical model explains the effect of these constraints on the growth, and in particular why the SAE growth rate is highly sensitive to the pattern geometry. Finally, the disagreement of the model at the largest pitch points to non-negligible multiple adatom recycling between patterned features. Overall, our findings point out the importance of considering adatom diffusion, adsorption and desorption dynamics in designing the SAE pattern to create pre-determined nanoscale structures across a wafer. These results are fundamental for the SAE process to become viable in the semiconductor industry.

Remote Doping of Scalable Nanowire Branches.

Selective-area epitaxy provides a path toward high crystal quality, scalable, complex nanowire networks. These high-quality networks could be used in topological quantum computing as well as in ultrafast photodetection schemes. Control of the carrier density and mean free path in these devices is key for all of these applications. Factors that affect the mean free path include scattering by surfaces, donors, defects, and impurities. Here, we demonstrate how to reduce donor scattering in InGaAs nanowire networks by adopting a remote-doping strategy. Low-temperature magnetotransport measurements indicate weak anti-localization-a signature of strong spin-orbit interaction-across a nanowire Y-junction. This work serves as a blueprint for achieving remotely doped, ultraclean, and scalable nanowire networks for quantum technologies.

Tuning growth direction of catalyst-free InAs(Sb) nanowires with indium droplets.

The need for indium droplets to initiate self-catalyzed growth of InAs nanowires has been highly debated in the last few years. Here, we report on the use of indium droplets to tune the growth direction of self-catalyzed InAs nanowires. The indium droplets are formed in situ on InAs(Sb) stems. Their position is modified to promote growth in the 〈11-2〉 or equivalent directions. We also show that indium droplets can be used for the fabrication of InSb insertions in InAsSb nanowires. Our results demonstrate that indium droplets can initiate growth of InAs nanostructures as well as provide added flexibility to nanowire growth, enabling the formation of kinks and heterostructures, and offer a new approach in the growth of defect-free crystals.

The Effect of Eccentric or Isometric Training on Strength, Architecture, and Sprinting across an Australian Football Season.

PURPOSE: This study aimed to investigate the effect of an isometric (ISO) or Nordic hamstring exercise (NHE) intervention, alongside a sprint training program on hamstring strength, architecture, and sprinting performance in Australian footballers. METHODS: Twenty-five male athletes undertook NHE ( n = 13) or ISO ( n = 12) training across a 38-wk period (including preseason and in season). Biceps femoris long head (BFlh) architecture, ISO, and eccentric knee flexor strength were assessed at baseline, at the end of preseason (14 wk), and at the conclusion of the intervention. Sprint times and force-velocity profiles were determined at baseline and at the end of preseason. RESULTS: After the intervention, both groups had significant improvements in BFlh fascicle length (NHE: 1.16 cm, 95% CI = 0.68 to 1.63 cm, d = 1.88, P < 0.001; ISO: 0.82 cm, 95% CI = 0.57 to 1.06 cm, d = 1.70, P < 0.001), muscle thickness (NHE: 0.11 cm, 95% CI = 0.01 to 0.21 cm, d = 0.51, P = 0.032; ISO: 0.21 cm, 95% CI = 0.10 to 0.32 cm, d = 0.86, P = 0.002), and eccentric strength (NHE: 83 N, 95% CI = 53 to 114 N, d = 1.79, P < 0.001; ISO: 83 N, 95% CI = 17 to 151 N, d = 1.17, P = 0.018). Both groups also finished the intervention weaker isometrically than they started (NHE: -45 N, 95% CI = -81 to -8 N, d = -1.03, P = 0.022; ISO: -80 N, 95% CI = -104 to -56 N, d = -3.35, P < 0.001). At the end of preseason, the NHE group had improved their 5-m sprint time by 3.3% ± 2.0%), and their maximum horizontal velocity was 3% ± 2.1% greater than the ISO group who saw no changes. CONCLUSIONS: Both ISO and NHE training with a periodized sprinting program can increase BFlh fascicle length, thickness, and eccentric strength in Australian footballers. NHE training also improves 5-m sprint time and maximum velocity. However, both interventions reduced ISO strength. These findings provide unique, contextually relevant insights into the adaptations possible in semiprofessional athletes.

Direct and integrating sampling in terahertz receivers from wafer-scalable InAs nanowires.

Terahertz (THz) radiation will play a pivotal role in wireless communications, sensing, spectroscopy and imaging technologies in the decades to come. THz emitters and receivers should thus be simplified in their design and miniaturized to become a commodity. In this work we demonstrate scalable photoconductive THz receivers based on horizontally-grown InAs nanowires (NWs) embedded in a bow-tie antenna that work at room temperature. The NWs provide a short photoconductivity lifetime while conserving high electron mobility. The large surface-to-volume ratio also ensures low dark current and thus low thermal noise, compared to narrow-bandgap bulk devices. By engineering the NW morphology, the NWs exhibit greatly different photoconductivity lifetimes, enabling the receivers to detect THz photons via both direct and integrating sampling modes. The broadband NW receivers are compatible with gating lasers across the entire range of telecom wavelengths (1.2-1.6 µm) and thus are ideal for inexpensive all-optical fibre-based THz time-domain spectroscopy and imaging systems. The devices are deterministically positioned by lithography and thus scalable to the wafer scale, opening the path for a new generation of commercial THz receivers.

Monolithic InSb nanostructure photodetectors on Si using rapid melt growth.

Monolithic integration of InSb on Si could be a key enabler for future electronic and optoelectronic applications. In this work, we report the fabrication of InSb metal-semiconductor-metal photodetectors directly on Si using a CMOS-compatible process known as rapid melt growth. Fourier transform spectroscopy demonstrates a spectrally resolved photocurrent peak from a single crystalline InSb nanostructure with dimensions of 500 nm × 1.1 µm × 120 nm. Time-dependent optical characterization of a device under 1550 nm illumination indicated a stable photoresponse with responsivity of 0.50 A W-1 at 16 nW illumination, with a time constant in the range of milliseconds. Electron backscatter diffraction spectroscopy revealed that the single crystalline InSb nanostructures contain occasional twin defects and crystal lattice twist around the growth axis, in addition to residual strain, possibly causing the observation of a low-energy tail in the detector response extending the photosensitivity out to 10 µm wavelengths (0.12 eV) at 77 K.

From Layer-by-Layer Growth to Nanoridge Formation: Selective Area Epitaxy of GaAs by MOVPE.

Selective area epitaxy at the nanoscale enables fabrication of high-quality nanostructures in regular arrays with predefined geometry. Here, we investigate the growth mechanisms of GaAs nanoridges on GaAs (100) substrates in selective area trenches by metal-organic vapor-phase epitaxy (MOVPE). It is found that pre-growth annealing results in the formation of valley-like structures of GaAs with atomic terraces inside the trenches. MOVPE growth of GaAs nanoridges consists of three distinct stages. Filling the trench in the first stage exhibits a step-flow growth behavior. Once the structure grows above the mask surface, it enters the second stage of growth by forming {101} side facets as the (100) flat top facet progressively shrinks. In the third stage, the fully formed nanoridge begins to overgrow onto the mask with a significantly reduced growth rate. We develop a kinetic model that accurately describes the width-dependent evolution of the nanoridge morphology through all three stages. MOVPE growth of fully formed nanoridges takes only about 1 min, which is 60 times faster than in our set of molecular beam epitaxy (MBE) experiments reported recently, and with a more regular, triangular cross-sectional geometry defined solely by the {101} facets. In contrast to MBE, no material loss due to Ga adatom diffusion onto the mask surface is observed in MOVPE until the third stage of growth. These results are useful for the fabrication of GaAs nanoridges of different dimensions on the same substrate for various applications and can be extended to other material systems.

International youth mental health case study of peer researchers' experiences.

BACKGROUND: The involvement of young people as peer researchers, especially with lived experience, is increasingly considered important in youth mental health research. Yet, there is variation in the understanding of the role, and limited evidence on its implementation across different research systems. This case study focusses on the barriers and enablers of implementing peer researcher roles within and across majority world countries contexts. METHODS: Based on an international youth mental health project involving different levels of peer researchers and participants from eight countries, peer researchers and a co-ordinating career researcher reflect on lessons regarding enabling and challenging factors. These reflections are captured and integrated by a systematic insight analysis process. RESULTS: Building on existing international networks, it was feasible to actively involve peer researchers with lived experience in a multi-country mental health study, who in turn recruited and engaged young participants. Identified challenges include the terminology and definition of the role, cultural differences in mental health concepts, and consistency across countries and sites. DISCUSSION: Peer researchers' role could be strengthened and mainstreamed in the future through ongoing international networks, training, sufficient planning, and active influence throughout the research process. TRIAL REGISTRATION: Not applicable.

The involvement of young people with lived experience as collaborators (peer researchers) in mental health research has become more prominent in recent years. Yet, there is variation in the understanding of this role and how to involve young people. There is also limited evidence on how this role can be applied across different research systems, especially in majority world countries. We share our experience from a youth mental health project involving peer researchers in eight countries. Peer researchers and the co-ordinating career researcher reflected on lessons regarding enabling and challenging factors. Their reflections highlighted that, overall, it is feasible to successfully involve young people with lived experience in international mental health research. Several challenges were also identified, including terminology, definition of roles, cultural differences in understanding mental health, and consistency across participating countries and sites. According to peer researchers' reflections, these challenges can be overcome through the establishment of ongoing international networks, training and support, sufficient planning and peer researchers getting involved at all the stages of the research. Lessons from this case study can be of interest to the international research community in strengthening the involvement of young people in mental health research.

Experiences of Using the Digital Support Tool MeeToo: Mixed Methods Study.

BACKGROUND: Digital peer support is an increasingly used form of mental health support for young people. However, there is a need for more research on the impact of digital peer support and why it has an impact. OBJECTIVE: The aim of this research is to examine young people's experiences of using a digital peer support tool: MeeToo. After the time of writing, MeeToo has changed their name to Tellmi. MeeToo is an anonymous, fully moderated peer support tool for young people aged 11-25 years. There were two research questions: (1) What impacts did using MeeToo have on young people? (2) Why did using MeeToo have these impacts on young people? METHODS: A mixed methods study was conducted. It involved secondary analysis of routinely collected feedback questionnaires, which were completed at two time points (T1 and T2) 2-3 months apart. Questionnaires asked about young people's (N=876) experience of using MeeToo, mental health empowerment, and well-being. Primary data were collected from semistructured interviews with 10 young people. RESULTS: Overall, 398 (45.4%) of 876 young people completed the T1 questionnaire, 559 (63.8%) completed the T2 questionnaire, and 81 (9.2%) completed both. Descriptive statistics from the cross-sectional analysis of the questionnaires identified a range of positive impacts of using MeeToo, which included making it easier to talk about difficult things, being part of a supportive community, providing new ways to help oneself, feeling better, and feeling less alone. Subgroup analysis (paired-sample t test) of 58 young females who had completed both T1 and T2 questionnaires showed a small but statistically significant increase in levels of patient activation, one of the subscales of the mental health empowerment scale: time 1 mean=1.83 (95% CI 1.72-1.95), time 2 mean=2.00 (95% CI 1.89-2.11), t59=2.15, and P=.04. Anonymity and the MeeToo sense of community were identified from interviews as possible reasons for why using MeeToo had these impacts. Anonymity helped to create a safe space in which users could express their feelings, thoughts, and experiences freely without the fear of being judged by others. The MeeToo sense of community was described as a valuable form of social connectedness, which in turn had a positive impact on young people's mental health and made them feel less isolated and alone. CONCLUSIONS: The findings of this research showed a range of positive impacts and possible processes for young people using MeeToo. Future research is needed to examine how these impacts and processes can be sustained.

GaAs nanowires on Si nanopillars: towards large scale, phase-engineered arrays.

Large-scale patterning for vapor-liquid-solid growth of III-V nanowires is a challenge given the required feature size for patterning (45 to 60 nm holes). In fact, arrays are traditionally manufactured using electron-beam lithography,for which processing times increase greatly when expanding the exposure area. In order to bring nanowire arrays one step closer to the wafer-scale we take a different approach and replace patterned nanoscale holes with Si nanopillar arrays. The method is compatible with photolithography methods such as phase-shift lithography or deep ultraviolet (DUV) stepper lithography. We provide clear evidence on the advantage of using nanopillars as opposed to nanoscale holes both for the control on the growth mechanisms and for the scalability. We identify the engineering of the contact angle as the key parameter to optimize the yield. In particular, we demonstrate how nanopillar oxidation is key to stabilize the Ga catalyst droplet and engineer the contact angle. We demonstrate how the position of the triple phase line at the SiO2/Si as opposed to the SiO2/vacuum interface is central for a successful growth. We compare our experiments with simulations performed in surface evolver™ and observe a strong correlation. Large-scale arrays using phase-shift lithography result in a maximum local vertical yield of 67% and a global chip-scale yield of 40%. We believe that, through a greater control over key processing steps typically achieved in a semiconductor fab it is possible to push this yield to 90+% and open perspectives for deterministic nanowire phase engineering at the wafer-scale.

Nanoscale Mapping of Light Emission in Nanospade-Based InGaAs Quantum Wells Integrated on Si(100): Implications for Dual Light-Emitting Devices.

III-V semiconductors outperform Si in many optoelectronics applications due to their high carrier mobility, efficient light emission and absorption processes, and the possibility to engineer their band gap through alloying. However, complementing Si technology with III-V semiconductors by integration on Si(100) remains a challenge still today. Vertical nanospades (NSPDs) are quasi-bi-crystal III-V nanostructures that grow on Si(100). Here, we showcase the potential of these structures in optoelectronics application by demonstrating InGaAs heterostructures on GaAs NSPDs that exhibit bright emission in the near-infrared region. Using cathodoluminescence hyperspectral imaging, we are able to study light emission properties at a few nanometers of spatial resolution, well below the optical diffraction limit. We observe a symmetric spatial luminescence splitting throughout the NSPD. We correlate this characteristic to the structure's crystal nature, thus opening new perspectives for dual wavelength light-emitting diode structures. This work paves the path for integrating optically active III-V structures on the Si(100) platform.

Patient and Public Involvement in Youth Mental Health Research: Protocol for a Systematic Review of Practices and Impact.

Various health settings have advocated for involving patients and members of the public (PPI) in research as a means to increase quality and relevance of the produced knowledge. However, youth PPI has been an understudied area. This protocol paper describes a new project that aims to summarize what is known about PPI with young people in mental health research. In line with the Preferred Reporting Items for Systematic reviews and Meta-Analyses Statement guidelines we will identify and appraise suitable articles and extract and synthesize relevant information including at least two reviewers at each stage of the process. Results will be presented in two systematic reviews that will describe (a) how youth PPI has been conducted (Review1) and (b) what impact youth PPI had on the subsequent research and on stakeholders (Review2). To our knowledge, this is the first set of reviews that uses a critical appraisal tool, which is co-developed with children and young people. Findings from this project will provide valuable insights and set out the key steps to adopting adequate PPI methods when involving children and young people in mental health research.

GaAs nanoscale membranes: prospects for seamless integration of III-Vs on silicon.

The growth of compound semiconductors on silicon has been widely sought after for decades, but reliable methods for defect-free combination of these materials have remained elusive. Recently, interconnected GaAs nanoscale membranes have been used as templates for the scalable integration of nanowire networks on III-V substrates. Here, we demonstrate how GaAs nanoscale membranes can be seamlessly integrated on silicon by controlling the density of nuclei in the initial stages of growth. We also correlate the absence or presence of defects with the existence of a single or multiple nucleation regime for the single membranes. Certain defects exhibit well-differentiated spectroscopic features that we identify with cathodoluminescence and micro-photoluminescence techniques. Overall, this work presents a new approach for the seamless integration of compound semiconductors on silicon.

Scapular kinematics during supraspinatus rehabilitation exercise: a comparison of full-can versus empty-can techniques.

BACKGROUND: Supraspinatus strengthening is an important component of shoulder rehabilitation. Previous work has determined that the full-can and empty-can exercises elicit the greatest amount of supraspinatus activity. However, scapular kinematics has not been considered when prescribing supraspinatus exercises. HYPOTHESIS: Scapular downward rotation, internal rotation, and anterior tipping during the empty-can exercise are increased when compared with the full-can exercise. STUDY DESIGN: Descriptive laboratory study. METHODS: Twenty participants performed full-can and empty-can exercises while an electromagnetic tracking system was used to collect three-dimensional scapular kinematic data. Scapular angles at 30 degrees, 60 degrees, and 90 degrees of the ascending and descending phases of humeral elevation were compared using 2-way repeated measures analysis of variance. RESULTS: There was more scapular anterior tipping and internal rotation during the empty-can exercise at all sampled humeral elevation angles except at 30 degrees of the descending phase for anterior/posterior tipping (P < .05). CONCLUSION: Scapular anterior tipping and internal rotation are increased during the empty-can exercise, whereas scapular upward rotation was not different between exercises. CLINICAL RELEVANCE: Increased scapular internal rotation and anterior tipping decrease the volume of the supraspinatus outlet during the empty-can exercise. When maintenance of the subacromial space is important, use of the full-can exercise seems most appropriate for selective strengthening of the supraspinatus muscle.