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Lisa M Harris, Eric C Y Tam, Struan J W Cummins, Martyn P Coles, J Robin Fulton
The reactivity of germanium phosphanido complexes with elemental chalcogens is reported. Addition of sulfur to [(BDI)GePCy2] (BDI = CH{(CH3)CN-2,6-iPr2C6H3}2) results in oxidation at germanium to form germanium(IV) sulfide [(BDI)Ge(S)PCy2] and oxidation at both germanium and phosphorus to form germanium(IV) sulfide dicylohexylphosphinodithioate complex [(BDI)Ge(S)SP(S)Cy2], whereas addition of tellurium to [(BDI)GePCy2] only gives the chalcogen inserted product, [(BDI)GeTePCy2]. This reactivity is different from that observed between [(BDI)GePCy2] and selenium...
February 17, 2017: Inorganic Chemistry
Matthew J Byrd, Erman Timurdogan, Zhan Su, Christopher V Poulton, Nicholas M Fahrenkopf, Gerald Leake, Douglas D Coolbaugh, Michael R Watts
We propose a mode-evolution-based coupler for high saturation power germanium-on-silicon photodetectors. This coupler uniformly illuminates the intrinsic germanium region of the detector, decreasing saturation effects, such as carrier screening, observed at high input powers. We demonstrate 70% more photocurrent generation (9.1-15.5 mA) and more than 40 times higher opto-electrical bandwidth (0.7-31 GHz) than conventional butt-coupled detectors under high-power illumination. The high-power and high-speed performance of the device, combined with the compactness of the coupling method, will enable new applications for integrated silicon photonics systems...
February 15, 2017: Optics Letters
B R Jany, N Gauquelin, T Willhammar, M Nikiel, K H W van den Bos, A Janas, K Szajna, J Verbeeck, S Van Aert, G Van Tendeloo, F Krok
Nano-sized gold has become an important material in various fields of science and technology, where control over the size and crystallography is desired to tailor the functionality. Gold crystallizes in the face-centered cubic (fcc) phase, and its hexagonal closed packed (hcp) structure is a very unusual and rare phase. Stable Au hcp phase has been reported to form in nanoparticles at the tips of some Ge nanowires. It has also recently been synthesized in the form of thin graphene-supported sheets which are unstable under electron beam irradiation...
February 14, 2017: Scientific Reports
Xiao Chen, Timothy T Fister, Jennifer L Esbenshade, Bing Shi, Xianyi Hu, Jinsong Wu, Andrew A Gewirth, Michael J Bedzyk, Paul Fenter
Group IV inter-metallics electrochemically alloy with Li with stoichiometries as high as Li4.4M (M=Si, Ge, Sn or Pb). This provides the second highest known specific capacity (after pure lithium metal) for lithium ion batteries, but the dramatic volume change during cycling greatly limits their use as anodes in Li-ion batteries. We describe an approach to overcome this limitation by constructing electrodes using a Ge/Ti multilayer architecture. In operando X-ray reflectivity and ex situ transmission electron microscopy are used to characterize the hetero-layer structure at various lithium stoichiometries along a lithiation/delithiation cycle...
February 13, 2017: ACS Applied Materials & Interfaces
Stephen A Graves, Paul A Ellison, Todd E Barnhart, Hector F Valdovinos, Eva R Birnbaum, Francois M Nortier, Robert J Nickles, Jonathan W Engle
Fe, Cu, and Al stacked foils were irradiated by 90 MeV protons at the Los Alamos Neutron Science Center's Isotope Production Facility to measure nuclear cross sections for the production of medically relevant isotopes, such as (52g)Mn, (54)Mn, (48)Cr, (55)Co, (58m)Co and (57)Ni. The decay of radioactive isotopes produced during irradiation was monitored using high-purity germanium gamma spectroscopy over the months following irradiation. Proton fluence was determined using the (nat)Al(p,x)(22)Na, (nat)Cu(p,x)(62)Zn (nat)Cu(p,x)(65)Zn, and (nat)Cu(p,x)(56)Co monitor reactions...
November 1, 2016: Nuclear Instruments & Methods in Physics Research. Section B, Beam Interactions with Materials and Atoms
Shen Hu, Edward L Lin, Ali K Hamze, Agham Posadas, HsinWei Wu, David J Smith, Alexander A Demkov, John G Ekerdt
Using in situ X-ray photoelectron spectroscopy, reflection high-energy electron diffraction, and density functional theory, we analyzed the surface core level shifts and surface structure during the initial growth of ABO3 perovskites on Ge (001) by atomic layer deposition, where A = Ba, Sr and B = Ti, Hf, Zr. We find that the initial dosing of the barium- or strontium-bis(triisopropylcyclopentadienyl) precursors on a clean Ge surface produces a surface phase that has the same chemical and structural properties as the 0...
February 7, 2017: Journal of Chemical Physics
Valerio Adinolfi, Edward H Sargent
The detection of infrared radiation enables night vision, health monitoring, optical communications and three-dimensional object recognition. Silicon is widely used in modern electronics, but its electronic bandgap prevents the detection of light at wavelengths longer than about 1,100 nanometres. It is therefore of interest to extend the performance of silicon photodetectors into the infrared spectrum, beyond the bandgap of silicon. Here we demonstrate a photovoltage field-effect transistor that uses silicon for charge transport, but is also sensitive to infrared light owing to the use of a quantum dot light absorber...
February 8, 2017: Nature
Shaili Sett, K Das, A K Raychaudhuri
We study the low-temperature electronic transport properties of single germanium nanowires (NWs) with diameters down to 45 nm to investigate the weak localization (WL) behavior and approach to metal-insulator transition (MIT) within them. The NWs (single crystalline) we investigate lie on the metallic side of the MIT with an extrapolated zero temperature conductivity [Formula: see text] in the range 23 to 1790 [Formula: see text] cm)(-1) and show a temperature-dependent conductivity which below 30 K can be described by a 3D WL behavior with Thouless length [Formula: see text] and [Formula: see text]...
March 22, 2017: Journal of Physics. Condensed Matter: An Institute of Physics Journal
Tomonori Fukuchi, Takashi Okauchi, Mika Shigeta, Seiichi Yamamoto, Yasuyoshi Watanabe, Shuichi Enomoto
PURPOSE: Positron emission tomography (PET) is a useful imaging modality that quantifies the physiological distributions of radiolabeled tracers in vivo in humans and animals. However, this technique is unsuitable for multiple-tracer imaging because the annihilation photons used for PET imaging have a fixed energy regardless of the selection of the radionuclide tracer. This study developed a multi-isotope PET (MI-PET) system and evaluated its imaging performance. METHODS: Our MI-PET system is composed of a PET system and additional γ-ray detectors...
February 7, 2017: Medical Physics
S M R Safaee, A PilAli, M A Karami
A nanoscale germanium-gold Schottky photodetector (PD) is proposed based on a nanoring supporting localized surface plasmon excitation. A design methodology is presented based on maximizing resonant transmission power throughput of light from the active region of the PD. Numerical calculations show significant field enhancement of about 200 times in the near-field zone inside of the nanoring, which is utilized to compensate the responsivity decrease due to PD active region volume shrinkage, providing the responsivity of 338  mA/W at a 1310 nm detection wavelength...
January 20, 2017: Applied Optics
Oliver Wiche, Dirk Tischler, Carla Fauser, Jana Lodemann, Hermann Heilmeier
Effects of citric acid and desferrioxamine B (DFO-B) on the availability of Ge and selected REEs (La, Nd, Gd, Er) to P. arundinacea were investigated. A soil dissolution experiment was conducted to elucidate the effect of citric acid and DFO-B at different concentrations (1 and 10 mmol l(-1) citric acid) on the release of Ge and REEs from soil. In a greenhouse plants of P. arundinacea were cultivated on soil and on sand cultures to investigate the effects of citric acid and DFO-B on the uptake of Ge and REEs by the plants...
February 3, 2017: International Journal of Phytoremediation
Beatriz Fernandez, Lara Lobo, Nies Reininghaus, Rosario Pereiro, Alfredo Sanz-Medel
Beside low production costs and the use of nontoxic and abundant raw materials, silicon based thin-film solar cells have the advantage to be built up as multi junction devices like tandem or triple junction solar cells. Silicon thin film modules made of tandem cells with hydrogenated amorphous silicon (a-Si:H) top cell and microcrystalline (μc) Si:H bottom cell are available on the market. In this work, the analytical potential of state-of-the art radiofrequency (rf) pulsed glow discharge (PGD) time of flight mass spectrometry (TOFMS) commercial instrumentation is investigated for depth profiling analysis of tandem-junctions solar cells on 2mm thick glass substrate with 1µm thick ZnO:Al...
April 1, 2017: Talanta
Jerzy Falandysz, Ji Zhang, Tamara Zalewska
This study, for the first time, presents the results of activity concentration determinations for (137)Cs and (40)K in a high number (21 species, 87 composite samples, and 807 fruiting bodies) of mushrooms of the genus Boletus from across Yunnan in 2011-2014 and Sichuan (Boletus tomentipes) using high-resolution high-purity germanium detector. Activity concentrations of (137)Cs demonstrated some variability and range from <4.4 to 83 ± 3 Bq kg(-1) dry biomass in caps and from <3.8 to 37 ± 3 Bq kg(-1) dry biomass in stipes, and of (40)K, respectively, from 420 ± 41 to 1300 ± 110 and from 520 ± 61 to 1300 ± 140 Bq kg(-1) dry biomass...
February 1, 2017: Environmental Science and Pollution Research International
Lingbing Kong, Wei Lu, Li Yongxin, Rakesh Ganguly, Rei Kinjo
The reactivity of L2PhB: (1; L = oxazol-2-ylidene) as well as its transition-metal (chromium and iron) complexes toward main-group substrates have been systematically examined, which led to the construction of B-E (E = C, Ga, Cl, H, F, N) bonds. The combination of 1 and triethylborane smoothly captured carbon dioxide concomitant with the formation of B-C and B-O bonds. The soft basic boron center in 1 readily reacted with soft acidic gallium trichloride (GaCl3) to afford the extremely stable adduct 4 involving a B-Ga dative bond...
January 30, 2017: Inorganic Chemistry
Tarek Morsi, Rehab Hegazy, Wael Badawy
The present study aims to assess the radiological parameters from gamma rays due to the uncontrolled disposal of porcelain waste to the environment. Qualitative and quantitative identification of radionuclides in the investigated samples was carried out by means of High-Purity Germanium (HPGe) detector. The average activity concentrations of the local porcelain samples were measured as 208.28 Bq/kg for (226)Ra, 125.73 Bq/kg for (238)U, 84.94 Bq/kg for (232)Th and 1033.61 Bq/kg for (40)K, respectively...
January 30, 2017: International Journal of Radiation Biology
Hiroki Tanimoto, Taro Fujiwara, Junta Mori, Tomohiko Nagao, Yasuhiro Nishiyama, Tsumoru Morimoto, Shunichiro Ito, Kazuo Tanaka, Yoshiki Chujo, Kiyomi Kakiuchi
We herein describe the syntheses and characterization of extended germa[N]pericyclynes, which are macrocycles composed of germanium-butadiyne units. The obtained novel extended germa[4]-[8]pericyclynes were characterized by X-ray crystallography, UV-Vis spectroscopy, fluorescence and phosphorescence emission spectroscopy, and cyclic voltammetry, and exhibited characteristic absorptions and emissions. Density functional theory (DFT) calculations suggested smaller HOMO-LUMO gap energy compared to that of general germapericyclynes...
January 30, 2017: Dalton Transactions: An International Journal of Inorganic Chemistry
Juan P Babaro, Kevin G West, Behrang H Hamadani
Spectral response measurements of germanium-based triple-junction solar cells were performed under a variety of light and voltage bias conditions. Two of the three junctions exhibited voltage and light bias dependent artifacts in their measured responses, complicating the true spectral response of these junctions. To obtain more insight into the observed phenomena, a set of current-voltage measurement combinations were also performed on the solar cells under identical illumination conditions, and the data were used in the context of a diode-based analytical model to calculate and predict the spectral response behavior of each junction as a function of voltage...
November 2016: Energy Sci Eng
A Drescher, M Yoho, S Landsberger, M Durbin, S Biegalski, D Meier, J Schwantes
A radiation detection system consisting of two cerium doped lanthanum bromide (LaBr3:Ce) scintillation detectors in a gamma-gamma coincidence configuration has been used to demonstrate the advantages that coincident detection provides relative to a single detector, and the advantages that LaBr3:Ce detectors provide relative to high purity germanium (HPGe) detectors. Signal to noise ratios of select photopeak pairs for these detectors have been compared to high-purity germanium (HPGe) detectors in both single and coincident detector configurations in order to quantify the performance of each detector configuration...
January 15, 2017: Applied Radiation and Isotopes
Xiaotian Guo, Zean Tian, Tinghong Gao, Quan Xie, Yongchao Liang, Yunfei Mo, Wanjun Yan
Understanding the structural evolution of covalent systems under rapid cooling is very important to establish a comprehensive solidification theory. Herein, we conducted molecular dynamics simulations to investigate the crystallization of silicon-germanium (SiGe) alloys. It was found that during crystallization, the saturation and orientation of covalent bonds are satisfied in order, resulting in three phase transitions. The saturation is satisfied during a continuous phase transition that occurs in the super-cooled liquid state...
January 27, 2017: Physical Chemistry Chemical Physics: PCCP
Daehwan Jung, Joseph Faucher, Samik Mukherjee, Austin Akey, Daniel J Ironside, Matthew Cabral, Xiahan Sang, James Lebeau, Seth R Bank, Tonio Buonassisi, Oussama Moutanabbir, Minjoo Larry Lee
Self-assembled nanocomposites have been extensively investigated due to the novel properties that can emerge when multiple material phases are combined. Growth of epitaxial nanocomposites using lattice-mismatched constituents also enables strain-engineering, which can be used to further enhance material properties. Here, we report self-assembled growth of highly tensile-strained Ge/In0.52Al0.48As (InAlAs) nanocomposites by using spontaneous phase separation. Transmission electron microscopy shows a high density of single-crystalline germanium nanostructures coherently embedded in InAlAs without extended defects, and Raman spectroscopy reveals a 3...
January 27, 2017: Nature Communications
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