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We conducted the coincidence measurement of $\alpha$ particles inelastically scattered from ${}^{20}$Ne at $0^{\circ}$ and decay charged particles in order to search for the alpha-particle condensed state. We compared the measured excitation-energy spectrum and decay branching ratio with the statistical-decay-model calculations, and found that the newly observed states at $E_x$ = 23.6, 21.8, and 21.2 MeV in ${}^{20}$Ne are strongly coupled to a candidate for the 4$\alpha$ condensed state in ${}^{16}$O. This result presents the first strong evidence that these states are the candidates for the 5$\alpha$ condensed state., Comment: 6 pages, 5 figures. The part of the analysis is updated, and some discussions are added

The reaction rate of the triple-alpha reaction can be enhanced in hot and dense environments due to the deexcitation of the Hoyle state in 12C by neutrons. The cross section of the deexcitation should be determined for the enhanced reaction rate. We plan to obtain the cross section by measuring the inverse reaction using a neutron beam around 10 MeV and an active target system. In the present paper, we report a proof-of-principle experiment using a neutron beam at 14 MeV. The obtained cross section is consistent with a previous result, demonstrating the validity of our method.

The cross sections of the $^{7}\mathrm{Be}(n,\ensuremath{\alpha})^{4}\mathrm{He}$ reaction for $p$-wave neutrons were experimentally determined at ${E}_{\mathrm{c}.\mathrm{m}.}=0.20--0.81\text{ }\text{ }\mathrm{MeV}$ slightly above the big bang nucleosynthesis (BBN) energy window for the first time on the basis of the detailed balance principle by measuring the time-reverse reaction. The obtained cross sections are much larger than the cross sections for $s$-wave neutrons inferred from the recent measurement at the n_TOF facility in CERN, but significantly smaller than the theoretical estimation widely used in the BBN calculations. The present results suggest the $^{7}\mathrm{Be}(n,\ensuremath{\alpha})^{4}\mathrm{He}$ reaction rate is not large enough to solve the cosmological lithium problem, and this conclusion agrees with the recent result from the direct measurement of the $s$-wave cross sections using a low-energy neutron beam and the evaluated nuclear data library ENDF/B-VII.1.

The cross sections of the 7 Be(n, α)4 He reaction for p -wave neutrons were experimentally determined at Ec.m. = 0.20−0.81 MeV close to the Big Bang nucleosynthesis (BBN) energy window for the first time on the basis of the detailed balance principle by measuring the time-reverse reaction. The obtained cross sections are much larger than the cross sections for s -wave neutrons inferred from the recent measurement at the n_TOF facility in CERN, but significantly smaller than the theoretical estimation widely used in the BBN calculations. The present results suggest the 7 Be(n, α)4 He reaction rate is not large enough to solve the cosmological lithium problem

Hot air and vacuum drying were performed to investigate changes in the moisture content, hardness, l-ascorbic acid content, antioxidant activity, and surface color of kiwifruit samples over the course of the drying process at temperatures of 50, 60, and 70 °C and a vacuum drying pressure of 3.00 kPa. The residual ratio of AsA and the antioxidant activity in the dried kiwifruit samples was 0.75–0.99 and 4.3–5.5, respectively. The l-ascorbic acid changes in the kiwifruit samples during the hot air drying process followed first order reaction kinetics. Changes in the sample hardness and antioxidant activity were represented by zero-order reaction kinetics. The sample surface color changes after drying were also measured, and the total color change (ΔE) of the samples at all temperatures and for each drying process was greater than 12. The sample color changes (Δa*) after vacuum drying at each temperature level were significantly (P

Embedded silicon carbon alloy (e-Si:C) technology for source and drain (S/D) is expected to improve nMOSFET drive current. The distribution and activation characteristics of arsenic in Si:C film and the interfacial solid-phase reaction of the Ni/Si:C system were studied with the aim of achieving the maximum improvement of the characteristics of e-Si:C S/D. It was clarified that the active carrier concentration of Si:C decreased with increasing carbon concentration compared to the control Si. There is concern that the low doping activation in Si:C increases series resistance of e-Si:C S/D nMOSFETs and degrades the performance gain expected from the strain effect.

The impacts of source and drain (S/D) doping on device performance in embedded SiGe (e-SiGe) p-channel metal–oxide–semiconductor field-effect transistor (pMOSFET) are presented. An in situ boron-doped e-SiGe S/D device exhibits higher drive current than a boron-implanted e-SiGe S/D device owing to its enhanced hole mobility and reduced parasitic resistance. The precise control of the recessed Si shape and the SiGe proximity to the channel is essential for utilizing the intrinsic benefit of an in situ boron-doped e-SiGe S/D. Moreover, it was confirmed that the channel stress induced by e-SiGe S/D increases as MOSFET size decreases. This indicates that the use of in situ boron-doped e-SiGe S/D is a promising technique for 32 nm node pMOSFET.

Carbon nanostructures (CN) have been selectively grown directly onto the top of nickel ion implanted nanopyramid array (Ni NPA) by the plasma enhanced chemical vapor deposition (p-CVD) technique. Firstly, NPA were fabricated by taking advantage of the anisotropic etching characteristics of silicon in hydrazine (N 2 H 4 H 2 O); where the ion implanted area acted as a mask for hydrazine etching. Secondly, carbon nanostructures were grown on Ni NPA by feeding methane/hydrogen (CH 4 /H 2 ) mixtures into p-CVD reactor. The change of concentration ratio of methane to hydrogen dramatically affected the growth selectivity of CN. Methane concentrations lower than 20%, promoted the selective growth of CN on the top of Ni NPA. Morphology and chemical nature of grown species were studied by employing scanning electron microscopy (SEM), and energy dispersive X-ray (EDX) spectroscopy, respectively.

Two-step recessed SiGe-S/D pMOSFET [1] has been optimized with a combination of compressive stress liner. Optimization on source and drain overlap, defect control and elevated SiGe-S/D structure are discussed experimentally. As a result of the careful optimization, record high drive current of 714 muA/mum at Vdd=1.0 V, Ioff =100 nA/mum at 24 nm gate length, is demonstrated.

The effects of inversion-layer capacitance and stress-induced mobility at short channel region (Lg =35 nm) on (100) and (110) pFETs are investigated. 64 % mobility enhancement at Eeff = 1.1 MV/cm and 0.15 nm thinner inversion-layer capacitance at Eox = 4.5 MV/cm are obtained for (110) embedded SiGe (eSiGe) pFETs, compared to (100) eSiGe pFETs. Calculated results suggest that (110) eSiGe pFETs will gain additional 63% higher mobility with 1 GPa uniaxial stress by controlling surface roughness scattering at SiO2/Si(110) interface.

For semiconductors to work properly, it is necessary to improve their electrical properties by adding small amounts of impurities, such as boron, to the semiconducting material, a process called doping. Until now it has been sufficient to introduce dopant atoms randomly. But as semiconductor devices continue to shrink, they will soon reach a size where fluctuations in dopant atom numbers will begin to influence electrical characteristics: dopant distribution can no longer be assumed to be homogeneous if the distance randomly separating these atoms is on a similar scale to the device itself. Shinada et al. have investigated the role of dopant disorder, using a recently developed single-ion implantation technique to implant dopant ions one-by-one into a fine semiconductor region. The results highlight the improvements in device performance that should be achievable through atomic-scale control of the doping process, and may even enhance the prospects for realizing silicon-based solid-state quantum computers. As the size of semiconductor devices continues to shrink, the normally random distribution of the individual dopant atoms within the semiconductor becomes a critical factor in determining device performance—homogeneity can no longer be assumed1,2,3,4,5. Here we report the fabrication of semiconductor devices in which both the number and position of the dopant atoms are precisely controlled. To achieve this, we make use of a recently developed single-ion implantation technique6,7,8,9, which enables us to implant dopant ions one-by-one into a fine semiconductor region until the desired number is reached. Electrical measurements of the resulting transistors reveal that device-to-device fluctuations in the threshold voltage (Vth; the turn-on voltage of the device) are less for those structures with ordered dopant arrays than for those with conventional random doping. We also find that the devices with ordered dopant arrays exhibit a shift in Vth, relative to the undoped semiconductor, that is twice that for a random dopant distribution (- 0.4 V versus -0.2 V); we attribute this to the uniformity of electrostatic potential in the conducting channel region due to the ordered distribution of dopant atoms. Our results therefore serve to highlight the improvements in device performance that can be achieved through atomic-scale control of the doping process. Furthermore, ordered dopant arrays of this type may enhance the prospects for realizing silicon-based solid-state quantum computers10.

We present a simple method for improving the field emission performance of tungsten-tip electron sources based on single-walled carbon nanotube (SWCNT) modification. By coating a sandwich-like thin film of Al–Fe–Al (with Fe as a catalyst) on a tungsten tip, SWCNTs were synthesized at 600 °C in a chemical vapor deposition (CVD) reactor. The influence of CNT modification on the electron emission characteristics of the emitters was investigated by means of a triode structure. We have found that CNT-modified tungsten tips exhibit low threshold-voltage for electron emission, and improved emission-current stability, compared with nonmodified and Al–Fe–Al-coated needles.