Several PSG variables that are indicative of sleep fragmentation, sleep disordered breathing, and poor sleep quality correlated with the occurrence of atherosclerosis, but total arousal index was the only independent predictive factor.
To investigate the decrease of thermal conductivity (
) of nanoscale Si materials, we conducted the piezoelectric photothermal (PPT) method for the highly periodic Si nanopillar arrays embedded in Si0.7Ge0.3. The PPT is an electrode free method that can measure a heat propagation in the parallel to the nanopillars direction. A distinctive dip was observed in the frequency-dependent PPT signal intensity. By focusing the dip frequency,
was estimated from the comparison with the model analysis based on the one-dimensional multilayer thermal diffusion equation. The estimated
was 0.19 ± 0.07 W m–1 K, in the parallel to the nanopillars direction. Since the considerable decrease of
was confirmed from the non-radiative recombination point of view, we found the present non-destructive PPT method is very useful to estimate
in the nanostructured devices for the thermoelectric application.
A new method to produce electrically steady ZnO films without any heating process has been developed by using plasma and electron beams to facilitate bonding between the metallic component and the oxygen on coated ZnO films. Both plasma atmosphere and electron beams can function as sources of nonequilibrium bonding energy, forming bridges between the zinc present in the zinc complex and the oxygen in the ZnO particles to construct a zinc-oxide thin film. Our results confirm that it is possible to achieve low conductive characteristics by controlling the acceleration voltage of electrons used to irradiate the ZnO coating. The electrically steady films fabricated have various potential applications, being particularly well-suited to electrical devices on a plastic medium.
Dehydroamination of 9-alkylamino-9,10-dihydrophenanthrene occurred at 190—250 °C under non-basic conditions to give phenanthrene exclusively. The thermal reaction of cis-9-t-butylamino-10-methoxy-9,10-dihydrophenanthrene gave both 9-methoxyphenanthrene and 9-t-butylaminophenanthrene, while 9-aminophenanthrene was obtained from the thermal reaction of 9-amino-10-methoxy-9,10-dihydrophenanthrene. The thermal reaction of 9-amino-9,10-dihydroanthracene gave both anthracene and 9-aminoanthracene. Analysis of activation energies and frequency factors showed that the dehydroamination proceeds via an intramolecular proton transfer from C-10 to the amino group and subsequent C–N bond cleavage.
Thermal management has become more critical as semiconductor devices are miniaturized. In metal–oxide–semiconductor field-effect transistors, the problem is the reduction in electron mobility in the channel layer owing to the temperature rise caused by heat generation near the channel-drain region. Focusing on the mean free paths of phonons and electrons in Si, nanostructures of a few 10 nm may only hinder heat propagation without affecting electron transportation. Therefore, inserting nanostructures into the channel layer may prevent a temperature rise and maintain a higher electron mobility. To discuss the relationship between the spacing between the nanopillars (NPs) and the heat generation and carrier behavior of the Si-NP/SiGe composite film, samples with NP spacings of 13, 27, or 47 nm were prepared. We previously confirmed that the thermal conductivity of the Si-NP/SiGe composite film decreased as NP spacing narrowed. The NPs scattered phonon propagation and suppressed heat propagation. However, carrier transport properties such as electrical conductivity, carrier mobility, and carrier lifetime have never been discussed. The laser heterodyne photothermal displacement method was used to examine the effect of nanostructures on carrier mobility and carrier lifetime of Si-NP/SiGe composite films. We observed that the carrier lifetime became longer when the NP spacing was comparable to the electron mean-free path of approximately 27 nm.
The laser heterodyne photothermal displacement (LH-PD) method was used to characterize the nonradiative recombination centers of semiconductors, such as defects and deep-lying electronic levels. When a semiconductor surface is irradiated with a modulated continuous wave laser, the irradiated area is periodically heated and expanded owing to the nonradiative recombination of the photoexcited carriers. The LH-PD can measure an absolute value of surface displacement and its time variation at various excitation beam frequencies [Formula: see text]. Si and GaAs substrate samples were used to confirm the usefulness of the proposed method. The obtained time variation of the surface displacement was well explained by theoretical calculations considering the carrier generation, diffusion, recombination, heat diffusion, and generated thermal strain. Because nonradiative carrier recombination generates local heat at defects in semiconductors, the LH-PD technique is useful for analyzing defect distributions. Additionally, measurements of intentional Fe-contaminated Si samples confirmed that this technique is suitable for defect mapping. Displacement mapping with changing [Formula: see text] suggests the potential to measure the distribution of nonradiative recombination centers in the sample depth direction.
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