Heteroepitaxial growth of GaAs on an Si substrate has been achieved through the use of crystalline SrTiO 3 (STO) and amorphous SiO 2 buffer layers. The buffer layers serve to accommodate some of the ...lattice mismatch between the substrate and the GaAs epilayers. Field-effect transistors fabricated in the GaAs epilayers show performance comparable to similar devices fabricated on GaAs substrates. The mobility in the GaAs/STO/Si sample is 2524 cm 2 /Vs compared to a GaAs/GaAs sample with mobility of 2682 cm 2 /Vs. A 0.7 μm gate length device has I/sub d max/ of 367 mA/mm and G/sub m max/ of 223 mS/mm. These devices also have good RF performance with f max of 14.5 GHz and class AB power density of 90 mW/mm with an associated power-added efficiency of 38% at 1.9 GHz. This RF performance is within experimental error of similar devices fabricated on GaAs substrates. Preliminary reliability results show that after 800 h at 200/spl deg/C, the GaAs/STO/Si sample showed 1.2% degradation in drain current.
Direct epitaxy of high-quality perovskite oxides on silicon paves the way for their integration with Si microelectronics. At Motorola Labs, we have achieved heteroepitaxy of high-quality perovskite ...oxide films and stacks on up to 8-in. Si and silicon-on-insulator (SOI) substrates by using molecular beam epitaxy. Alkaline earth metals are used to remove the native oxide on Si and SOI at 720–800 °C, well below the SiO
2 thermal desorption temperatures. A stable (2×1) surface structure is the critical enabling template for oxide epitaxy on silicon. Unit cell-by-unit cell growth of SrTiO
3 (STO) by using co-deposition of Sr and Ti in oxygen promotes Ti oxidation and produces higher-quality films on Si, compared to a layer-by-layer flux shuttering technique, especially at the initial nucleation stage. Characteristic half-order reconstructions of the perovskite oxide surface are useful in real-time stoichiometry monitoring and control during growth
while the wafers are rotating. Amorphous interfacial layer between the epitaxial oxide and silicon can be tailored by controlling the oxide growth process and parameters. Al-doping is found to expand the band gap and reduce the leakage current density in the STO films.
Self-aligned GaAs enhancement mode MOS heterostructure field-effect transistors (MOS-HFET) have been successfully fabricated for the first time. The MOS devices employ a Ga 2 O 3 gate oxide, an ...undoped Al/sub 0.75/Ga/sub 0.25/As spacer layer, and undoped In/sub 0.2/Ga/sub 0.8/As as channel layer. The p-channel devices with a gate length of 0.6 μm exhibit a maximum DC transconductance g/sub m/ of 51 mS/mm which is an improvement of more than two orders of magnitude over previously reported results. With the demonstration of a complete process flow and 66% of theoretical performance, GaAs MOS technology has moved into the realm of reality.
Abstract
Background
User involvement in developing community-based public health services has been on the agenda for decades. User involvement refers to the variety of ways in which service users or ...public citizens participate in the development of health services: from proving information on their needs to actively being involved in decisions about future services. Former studies found that user involvement is meaningful to the people involved and could have a favorable impact on the quality of services. Thus, it is timely to systematically identify and provide a comprehensive overview of user involvement methods used in public health studies. The aim of this scoping review is to provide an overview of the current body of empirical research where user involvement methods have been used to develop community public health services and identify its possible impact on the individual as well as services.
Methods
A systematic scoping review of user involvement methods aiming to develop public health services followed Arksey and O'Malley, 2005 framework. Six databases: CINAHL, Cochrane Library, Embase, PsycINFO. PubMed, Scopus and ProQuest, were searched from October till November, 2019. Search terms were: user involvement, methods and health care with corresponding synonym. All hits were double screened.
Results
6.044 studies were identified of which 38 studies lived up to the criteria. Preliminary findings from coding and synthesizing studies have identified a variety of user involvement
Methods
19 of the studies used complex, multi-facetted packages of methods aiming to identify needs, prioritize and formulate recommendations for future services. 19 studies used different kinds of group meetings and some used certain techniques to facilitate the process. Many reported the impact, and 13 evaluated the methods. The impact of using the methods varied from impact on individual, group, or service/political level. Final results will be presented at the conference.
Key messages
Studies on user involvement methods in developing community public health services and its impact are sparse. User involvement is privotal in developing sustainable public health community services.
Abstract
Background
Mounting evidence suggests that mental health problems in pregnant women may negatively affect the intra- and extrauterine health and development of the child. This is especially ...of concern as the prevalence of mental health problems in pregnant women is high and believed to be increasing. We set out to quantify the effect of maternal mental health status on the risk of adverse perinatal outcomes for the infant.
Methods
We undertook a nationwide register-based cohort study including children born alive in Denmark between 2000 and 2016. The exposed cohort was children born to mothers with mental health problems in the two years prior to childbirth that had been cared for in primary care settings only (Group 1, minor problems, n = 71 759) or had required psychiatric intervention (Group 2, moderate-severe problems, n = 41 099). All non-exposed children served as comparison group (n = 908 268). We calculated risk ratios (RRs) with 95% confidence intervals (CI) for each perinatal outcome of interest.
Results
Infants in Group 1 as well as Group 2 were at higher risk of neonatal death than infants born to unaffected mothers, although for Group 2 the trend was non-significant (Group 1: adjusted RR (aRR) 1.34, 95% CI 1.17-1.52; Group 2: aRR 1.11, 95% CI 0.94-1.32). Both exposure groups were furthermore at significantly increased risk of 5-minute Apgar scores <7 (Group 1: aRR 1.27, 95% CI 1.17-1.37; Group 2: aRR 1.52, 95% CI 0.94-1.32) and <4 (Group 1: aRR 1.26, 95% CI 1.10-1.44; Group 2: aRR 1.28, 95% CI 1.08-1.52) and of hospital admission in the neonatal period (Group 1: aRR 1.22, 95% CI 1.19-1.24; Group 2: 1.29, 95% CI 1.26-1.32), paralleled by a significantly higher risk of preterm birth and several neonatal morbidities.
Conclusions
Infants born to mothers with moderate-severe as well as minor mental health problems were at increased risk of multiple adverse perinatal outcomes, thus calling for effective preventive strategies to improve outcomes in both groups.
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