321,658 research outputs found
[Report to Chief J. E. Curry, by an unknown author #1]
No full textReport to Chief J. E. Curry, by an unknown author. The report contains a list of officers who gave depositions to the United States Attorney
[Report to Chief J. E. Curry, by an unknown author #2]
No full textReport to Chief J. E. Curry, by an unknown author. The report contains a list of officers who gave depositions to the United States Attorney
J(Si,H) Coupling Constants of Activated Si-H Bonds
Full text linkWe outline in this combined experimental and theoretical NMR study that sign and magnitude of J(Si,H) coupling constants provide reliable indicators to evaluate the extent of the oxidative addition of Si-H bonds in hydrosilane complexes. In combination with experimental electron density studies and MO analyses a simple structure-property relationship emerges: positive J(Si,H) coupling constants are observed in cases where M → L π-back-donation (M = transition metal; L = hydrosilane ligand) dominates. The corresponding complexes are located close to the terminus of the respective oxidative addition trajectory. In contrast negative J(Si,H) values signal the predominance of significant covalent Si-H interactions and the according complexes reside at an earlier stage of the oxidative addition reaction pathway. Hence, in nonclassical hydrosilane complexes such as Cp2Ti(PMe3)(HSiMe3-nCln) (with n = 1-3) the sign of J(Si,H) changes from minus to plus with increasing number of chloro substituents n and maps the rising degree of oxidative addition. Accordingly, the sign and magnitude of J(Si,H) coupling constants can be employed to identify and characterize nonclassical hydrosilane species also in solution. These NMR studies might therefore help to reveal the salient control parameters of the Si-H bond activation process in transition-metal hydrosilane complexes which represent key intermediates for numerous metal-catalyzed Si-H bond activation processes. Furthermore, experimental high-resolution and high-pressure X-ray diffraction studies were undertaken to explore the close relationship between the topology of the electron density displayed by the η2(Si-H)M units and their respective J(Si,H) couplings. (Chemical Equation Presented)
Helium irradiation effects in polycrystalline Si, silica, and single crystal Si
Full text linkTransmission electron microscopy (TEM) has been used to investigate the effects of room temperature 6 keV helium ion irradiation of a thin (≈55 nm thick) tri-layer consisting of polycrystalline Si, silica, and single-crystal Si. The ion irradiation was carried out in situ within the TEM under conditions where approximately 24% of the incident ions came to rest in the specimen. This paper reports on the comparative development of irradiation-induced defects (primarily helium bubbles) in the polycrystalline Si and single-crystal Si under ion irradiation and provides direct measurement of a radiation-induced increase in the width of the polycrystalline layer and shrinkage of the silica layer. Analysis using TEM and electron energy-loss spectroscopy has led to the hypothesis that these result from helium-bubble-induced swelling of the silicon and radiation-induced viscoelastic flow processes in the silica under the influence of stresses applied by the swollen Si layers. The silicon and silica layers are sputtered as a result of the helium ion irradiation; however, this is estimated to be a relatively minor effect with swelling and stress-related viscoelastic flow being the dominant mechanisms of dimensional change
Formation of silicon nanodots via ion beam sputtering of ultrathin gold thin film coatings on Si
Full text linkIon beam sputtering of ultrathin film Au coatings used as a physical catalyst for self-organization of Si nanostructures has been achieved by tuning the incident particle energy. This approach holds promise as a scalable nanomanufacturing parallel processing alternative to candidate nanolithography techniques. Structures of 11- to 14-nm Si nanodots are formed with normal incidence low-energy Ar ions of 200 eV and fluences above 2 x 10(17) cm(-2). In situ surface characterization during ion irradiation elucidates early stage ion mixing migration mechanism for nanodot self-organization. In particular, the evolution from gold film islands to the formation of ion-induced metastable gold silicide followed by pure Si nanodots formed with no need for impurity seeding
J-V Characteristics of Amorphous Si/Crystalline Si Heterojunction
No full text비정질 Si(a-Si)/ 결정질 Si(c-Si) heterojunction의 J-V특성을 조사하기 위하여 a-Si/C-Si/Pd heterojunction-Schottky barrier 복합체를 사용하였다.
a-Si은 약10 ??Torr의 진공속에서 다결정 Si을 진공증착시켜 제작하였으며 600K하에서 hydrogenation과 annealing처리가 되었다.
a-Si/c-Si hetherojunction의 J-V특성은 이중 Schottyky barrier model로 설명될 수 있으며 V=(kT/q)[β₁log(J/J?? +1)-β₂log(1-J/J ??)]의 식을 만족한다. 여기서 β₁과 β₂는 diode quality factor이다.To investigate the J-V characteristics of amorphous Si(a-Si)/crystalline Si(c-Si) heterojunction, c-Si/a-Si/Pd heterojunction-Schottke barrier complexes were wused. a-Si films were fabricated by vacuum_~10 Torr) evaporation of polycrystalline Si and then hydrogenated and annealed at 600K.
The J-V characteristics of a-Si/c-Si heterojunction can be explained by double Schottky barrier model and is given V=(kT/q)[b₁log(J/J +1)-b₂log(1-J/J )], where b₁,b₂are diode quality factors.To investigate the J-V characteristics of amorphous Si(a-Si)/crystalline Si(c-Si) heterojunction, c-Si/a-Si/Pd heterojunction-Schottke barrier complexes were wused. a-Si films were fabricated by vacuum_~10 Torr) evaporation of polycrystalline Si and then hydrogenated and annealed at 600K.
The J-V characteristics of a-Si/c-Si heterojunction can be explained by double Schottky barrier model and is given V=(kT/q)[b₁log(J/J +1)-b₂log(1-J/J )], where b₁,b₂are diode quality factors
Murder on the mountain: author talk with Peter J. Wosh
No full textAuthor talk by Peter J. Wosh on May 5th, 2022, on his book, "Murder on the Mountain: crime, passion, and punishment in gilded age New Jersey.
Mr. Melvin J. Collier, RWWL AUC, June 2011
No full textThis video is a conversation with Mr. Melvin J. Collier. Mr. Collier talks about his book, "From Mississippi to Africa: A Journey of Discovery". Daniel Le, AUC Woodruff Library, is the interviewer
Ge-on-Si single-photon avalanche diode detectors: design, modeling, fabrication, and characterization at wavelengths 1310 and 1550 nm
Full text linkThe design, modeling, fabrication, and characterization of single-photon avalanche diode detectors with an epitaxial Ge absorption region grown directly on Si are presented. At 100 K, a single-photon detection efficiency of 4% at 1310 nm wavelength was measured with a dark count rate of ~ 6 megacounts/s, resulting in the lowest reported noise-equivalent power for a Ge-on-Si single-photon avalanche diode detector (1×10-14 WHz-1/2). The first report of 1550 nm wavelength detection efficiency measurements with such a device is presented. A jitter of 300 ps was measured, and preliminary tests on after-pulsing showed only a small increase (a factor of 2) in the normalized dark count rate when the gating frequency was increased from 1 kHz to 1 MHz. These initial results suggest that optimized devices integrated on Si substrates could potentially provide performance comparable to or better than that of many commercially available discrete technologies
Mechanism of vertical Ge nanowire nucleation on Si (111) during subeutectic annealing and growth
Full text linkThe direct integration of Ge nanowires with silicon is of interest in multiple applications. In this work, we describe the growth of high-quality, vertically oriented Ge nanowires on Si (111) substrates utilizing a completely sub-Au-Si-eutectic annealing and growth procedure. With all other conditions remaining identical, annealing below the Au-Si eutectic results in successful heteroepitaxial nucleation and growth of Ge nanowires on Si substrate while annealing above the Au-Si eutectic leads to randomly oriented growth. A model is presented to elucidate the effect of the annealing temperature, in which we hypothesized that sub-Au-Si-eutectic annealing leads to the formation of a single and well-oriented interface, essential to template heteroepitaxial nucleation. These results are critically dependent on substrate preparation and lead to the creation of integrated nanowire systems with a low thermal budget process
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