Y. Kim

Si-based magnetic tunnel transistor with single CoFe base layer

Magnetic tunnel transistors were prepared on Si(100) substrates by magnetron sputter deposition. By means of spin filtering through a single Co90Fe10 base layer, magnetocurrent ratios of 53%–55% and high transfer ratios of (1–2)×10−4 for emitter-base bias of 1.5–2V were obtained at 77K. The bias dependence of the collector current showed the square-law behavior. From the modified Bell-Kaiser model, attenuation lengths of majority and minority spins of hot electrons are expected as 40±5 and 16±1A in the single Co90Fe10 layer, respectively. The decrease of transfer ratio was observed with decreasing base thickness from 80 to 30A, which may be related to the extension of the (Co2Si and Fe) intermediate region formed at Co90Fe10∕Si interface in the thinner base layer.

Development and preliminary evaluation of culturally specific web-based intervention for parents of adolescents

WHAT IS KNOWN ON THE SUBJECT?: Problematic parent-child relationships have been identified as one of the main predictors of adolescents mental health problems, but there are few existing interventions that address this issue. The format and delivery method of existing interventions for parents are relatively inaccessible for parents with full-time jobs and families living in rural areas. WHAT DOES THIS PAPER ADD TO EXISTING KNOWLEDGE?: The newly developed Stepping Stone culturally specific web-based intervention, which is intended to help Korean parents of adolescents to acquire both knowledge and communication and conflict management skills, was found to be feasible and well-accepted by parents. This study enabled us to identify areas for improvement in the content and format of the intervention and strategies. This will potentially increase effect sizes for the outcome variables of parents perception and behaviours. WHAT ARE THE IMPLICATIONS FOR PRACTICE?: This web-based intervention could be delivered across diverse settings, such as schools and community mental health centers, to increase parents knowledge of adolescents mental health and allow for early detection of mental health problems. Mental health nurses working in schools may spend a significant amount of time addressing students mental health issues; thus, this web-based intervention could be a useful resource to share with parents and children. In this way, the mental health nurses could facilitate parental engagement in the intervention and then help them to continue to apply and practice the knowledge and skills obtained through the program.nnnABSTRACTnIntroduction There is a need for accessible, culturally specific web-based interventions to address parent-child relationships and adolescents mental health. Aims This study developed and conducted a preliminary evaluation of a 4-week web-based intervention for parents of adolescents aged 11 to 16xa0years in Korea. Methods We used a two-group, repeated measures, quasi-experimental study design to assess the feasibility of developing and implementing a web-based intervention for parents. Descriptive statistics, chi-square and t tests, and mixed effect modeling were used for data analysis. Results The intervention and 1-month follow-up survey were completed by 47 parents in the intervention group and 46 parents in the attention control (AC) group. The intervention was found to be feasible and well-accepted by parents. Discussion This culturally specific web-based intervention is a useful tool for knowledge dissemination among large numbers of parents. Areas for improvement in the content and format of the intervention and strategies to elicit significant parent-child interactions are provided. Implications for practice and conclusion The intervention could be disseminated in collaboration with mental health nurses working in schools to facilitate parents participation.

On Direct Observation of Diffusion by Aberration-Corrected HREM

Renewable energy sources such as wind and solar energy, despite their abundance and availability, are variable and uncontrolled [1]. A continuous supply of clean energy therefore requires a significant expansion in energy storage and conversion technologies. Solid electrolytes enable technologies that can both convert (fuel cells) and store (batteries) electrical energy. The ability of solid electrolytes to conduct ions will depend largely on microstructural defects in the material. Line and planar defects can scatter ions or build up a space-charge layer to affect ionic conductivity. More fundamentally, the diffusion of ions will be closely correlated to point-defect diffusion. Our aim is to conduct dynamic in-situ experiments to study the role of defects in a solid electrolyte by direct observation of atomic motion at and along defects using aberration-corrected HREM. Since conductivity (σ) is proportional to jump frequency (Γ), experiments that directly observe jump frequency will provide fundamental insight into charge-transport processes in these materials.

Removal of Surface Damage from Focused Ion Beam using Plasma Cleaner

Surface damage in the thinned samples is a bottleneck for the critical analysis in transmission electron microscopy(TEM). Ion milling conditions used in conventional sample preparation (3~8keV, 10-30 μA) leave amorphous layer on the surfaces, which varies ~ 3-6 nm in thickness. (make references from the table at the end) In the TEM sample prepared using Focused Ion Beam(FIB), it is more difficult to remove the surface Ga-rich layer because of the geometry of the thinned area. Low energy ion beam milling is so far the most effective way to remove the surface damage formed by either ion milling or Focused Ion Beam(FIB). Instead of using directional low energy ion beam to remove the surface damage, plasma cleaner, typically used in the analysis of scanning transmission electron microscopy (STEM) to minimize the carbon contamination, was utilized to make low energy milling effect in this study. Basic idea is to bombard the surface applying bias to the sample in the high density plasma formed by Radio Frequency wave.

Structural characterization of metal organic vapor phase epitaxy grown GaInNAs quantum well with InGaAs and GaNAs barriers

The effects of InGaAs∕GaNAs barrier combinations were investigated in the metal organic vapor phase epitaxy grown GaInNAs quantum wells (QWs). Significant improvement was made in the optical performance of the 1.3μm range with the proposed structures. Structural investigation linked with the optical properties reveals that a thin InGaAs layer, placed between GaInNAs QWs and GaNAs layers, plays a role in redistributing the nitrogen within the QWs while maintaining a sharp interface. The amount of diffused nitrogen is proportional to the strain residing in the InGaAs layer, which explains the tendency of blueshift with the increase in GaNAs thickness.