Direct Semiconductor Wafer Bonding in Non-Cleanroom Environment: Understanding the Environmental Influences on Bonding

We investigated semiconductor direct wafer bonding in a regular, non-cleanroom environment to understand environmental influences on bonding characteristics. The correlations among surface treatments, particle densities, bonding strengths, and interfacial conductivities were systematically investigated. On the basis of our investigation and condition optimization, we realized direct semiconductor bonding in the regular atmosphere with high interfacial mechanical stabilities and electrical conductivities, sufficient for device applications. Furthermore, we demonstrated fabrication and operation of solar cells using the developed bonding technique, with current paths across the bonded interfaces. These results and related technical insights may be useful for a low-cost, simpler manufacture of high-performance electrical and optical devices

Prompt GeV-TeV Emission of Gamma-Ray Bursts Due to High-Energy Protons, Muons and Electron-Positron Pairs

In the framework of the internal shock scenario, we model the broadband prompt emission of gamma-ray bursts (GRBs) with emphasis on the GeV-TeV bands, utilizing Monte Carlo simulations that include various processes associated with electrons and protons accelerated to high energies. While inverse Compton emission from primary electrons is often dominant, different proton-induced mechanisms can also give rise to distinct high-energy components, such as synchrotron emission from protons, muons or secondary electrons/positrons injected via photomeson interactions. In some cases, they give rise to double spectral breaks that can serve as unique signatures of ultra-high-energy protons. We discuss the conditions favorable for such emission, and how they are related to the production of ultra-high-energy cosmic rays and neutrinos in internal shocks. Ongoing and upcoming observations by {\it GLAST}, atmospheric Cerenkov telescopes and other facilities will test these expectations and provide important information on the physical conditions in GRB outflows.Comment: 11 pages, 8 figures and 14 appendix figures, accepted for publication in ApJ vol. 671 with minor revision

Wavelength-Conversion-Material-Mediated Semiconductor Wafer Bonding for Smart Optoelectronic Interconnects

A new concept of semiconductor wafer bonding, mediated by optical wavelength conversion materials, is proposed and demonstrated. The fabrication scheme provides simultaneous bond formation and interfacial function generation, leading to efficient device production. Wavelength-converting functionalized semiconductor interfacial engineering is realized by utilizing an adhesive viscous organic matrix with embedded fluorescent particles. The bonding is carried out in ambient air at room temperature and therefore provides a cost advantage with regard to device manufacturing. Distinct wavelength conversion, from ultraviolet into visible, and high mechanical stabilities and electrical conductivities in the bonded interfaces are verified, demonstrating their versatility for practical applications. This bonding and interfacial scheme can improve the performance and structural flexibility of optoelectronic devices, such as solar cells, by allowing the spectral light incidence suitable for each photovoltaic material, and photonic integrated circuits, by delivering the respective preferred frequencies to the optical amplifier, modulator, waveguide, and detector materials

Delayed Onset of High-Energy Emissions in Leptonic and Hadronic Models of Gamma-Ray Bursts

The temporal--spectral evolution of the prompt emission of gamma-ray bursts (GRBs) is simulated numerically for both leptonic and hadronic models. For weak enough magnetic fields, leptonic models can reproduce the few seconds delay of the onset of GeV photon emission observed by Fermi-LAT, due to the slow growth of the target photon field for inverse Compton scattering. However, even for stronger magnetic fields, the GeV delay can be explained with hadronic models, due to the long acceleration timescale of protons and the continuous photopion production after the end of the particle injection. While the FWHMs of the MeV and GeV lightcurves are almost the same in one-zone leptonic models, the FWHM of the 1--30 GeV lightcurves in hadronic models are significantly wider than those of the 0.1--1 MeV lightcurves. The amount of the GeV delay depends on the importance of the Klein--Nishina effect in both the leptonic and hadronic models. In our examples of hadronic models the energies of the escaped neutrons are comparable to the gamma-ray energy, although their contribution to the ultra high-energy cosmic rays is still subdominant. The resulting neutrino spectra are hard enough to avoid the flux limit constraint from IceCube. The delay of the neutrino emission onset is up to several times longer than the corresponding delay of the GeV photon emission onset. The quantitative differences in the lightcurves for various models may be further tested with future atmospheric Cherenkov telescopes whose effective area is larger than that of Fermi-LAT, such as CTA.Comment: Accepted for publication in ApJ; 35 pages, 17 figure

The Effect of Cranial Change on Oropharyngeal Airway and Breathing During Sleep

Mandibular micrognathia is one of the characteristics of obstructive sleep apnea syndrome. The purpose of this study was to assess the effects of bimaxillary surgery without maxillary advancement on the upper airway using computational fluid dynamics (CFD) results of comparing pre- and post-operative finite element model. Seven female patients with jaw deformity, who underwent two-jaw surgery (Le Fort1 osteotomy and bilateral sagittal split ramus osteotomy; BSSRO) were enrolled. Maxillary was moved for correcting occlusal plane and mandibular was moved to advancement. Pharyngeal airway space and breathing during sleep were evaluated, comparing the periods of 2 days before and 6 months after the operation. The cross-sectional area of the level of the hard palate (HP) and the level of the tip of the uvula (TU), and airway volume of total, HP-TU, and TP- the level of the base of the epiglottis (BE) were increased. AI and AHI in 2 days before and 6 months after were decreased. As the result of nasal ventilation condition, velocity of HP and TU in 2 days before and 6 months after were decreased. We think that it was revealed that movement of the maxilla without advancement did not affect to the morphology and function of airway

Design of a multipurpose sample cell holder for the Diamond Light Source high-throughput SAXS beamline B21

The design of a multipurpose sample cell holder for the high-throughput (HT) beamline B21 is presented. The device is compatible with the robot bioSAXS sample changer currently installed on BM29, ESRF, and P12 Petra IV synchrotrons. This work presents an approach that uses 3D-printing to make hardware alterations which can expand the versatility of HT beamlines at low cost

Spectral-Temporal Simulations of Internal Dissipation Models of Gamma-Ray Bursts

We present calculations of the time evolution of the prompt spectra of gamma-ray burst models involving generic internal dissipation regions, including internal shocks, either by itself or in the presence of an external photon source such as a photosphere. The method uses a newly developed time-dependent code involving synchrotron emission and absorption, inverse Compton scattering and pair formation. The models reproduce the typical observed Band spectra and their generic time evolution, including the appearance of an extra keV-GeV component, whose delay in simple SSC models, however, is only partially able to explain the several seconds observed GeV delays. On the other hand, models involving both a photosphere and an internal dissipation region at a larger radius produce both an extra GeV component and time delays which are in the range of the observations.Comment: 37 pages, 15 figures, accepted for publication in The Astrophysical Journa