13 research outputs found

    Temperature mapping of stacked silicon dies from x-ray diffraction intensities

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    Increasing power densities in integrated circuits has led to an increased prevalence of thermal hotspots in integrated circuits. Tracking these thermal hotspots is imperative to prevent circuit failures. In 3D integrated circuits, conventional surface techniques like infrared thermometry are unable to measure 3D temperature distribution and optical and magnetic resonance techniques are difficult to apply due to the presence of metals and large current densities. X-rays offer high penetration depth and can be used to probe 3D structures. We report a method utilizing the temperature dependence of x-rays diffraction intensity via the Debye-Waller factor to simultaneously map the temperature of an individual silicon die that is a part of a stack of dies. Utilizing beamline 1-ID-E at the Advanced Photon Source (Argonne), we demonstrate for each individual silicon die, a temperature resolution of 3 K, a spatial resolution of 100 um x 400 um and a temporal resolution of 20 s. Utilizing a sufficiently high intensity laboratory source, e.g., from a liquid anode source, this method can be scaled down to laboratories for non-invasive temperature mapping of 3D integrated circuits

    3D Atomic Arrangement at Functional Interfaces Inside Nanoparticles by Resonant High-Energy X‑ray Diffraction

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    With current science and technology moving rapidly into smaller scales, nanometer-sized materials, often referred to as NPs, are produced in increasing numbers and explored for numerous useful applications. Evidence is mounting, however, that useful properties of NPs can be improved further and even new NP functionality achieved by not only controlling the NP size and shape but also interfacing chemically or structurally distinct entities into single, so-called “composite” NPs. A typical example is core–shell NPs wherein the synergy of distinct atoms at the core\shell interface endows the NPs with otherwise unachievable functionality. However, though advantageous, the concept of functional interfaces inside NPs is still pursued largely by trial-and-error. That is because it is difficut to assess the interfaces precisely at the atomic level using traditional experimental techniques and, hence, difficult to take control of. Using the core\shell interface in less than 10 nm in size Ru core–Pt shells NPs as an example, we demonstrate that precise knowledge of the 3D atomic arrangement at functional interfaces inside NPs can be obtained by resonant high-energy X-ray diffraction (XRD) coupled to element-specific atomic pair distribution function (PDF) analysis. On the basis of the unique structure knowledge obtained, we scrutinize the still-debatable influence of core\shell interface on the catalytic functionality of Ru core–Pt shell NPs, thus evidencing the usefulness of this nontraditional technique for practical applications

    Pt–Au Alloying at the Nanoscale

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    The formation of nanosized alloys between a pair of elements, which are largely immiscible in bulk, is examined in the archetypical case of Pt and Au. Element specific resonant high-energy X-ray diffraction experiments coupled to atomic pair distribution functions analysis and computer simulations prove the formation of Pt–Au alloys in particles less than 10 nm in size. In the alloys, Au–Au and Pt–Pt bond lengths differing in 0.1 Å are present leading to extra structural distortions as compared to pure Pt and Au particles. The alloys are found to be stable over a wide range of Pt–Au compositions and temperatures contrary to what current theory predicts. The alloy-type structure of Pt–Au nanoparticles comes along with a high catalytic activity for electrooxidation of methanol making an excellent example of the synergistic effect of alloying at the nanoscale on functional properties

    Resolving Atomic Ordering Differences in Group 11 Nanosized Metals and Binary Alloy Catalysts by Resonant High-Energy X‑ray Diffraction and Computer Simulations

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    Resonant high-energy X-ray diffraction coupled to atomic pair distribution function analysis and computer simulations is used to study the atomic-scale structure of group 11 nanosized metals and binary alloy catalysts. We find that nanosized Cu is quite disordered structurally whereas nanosized Ag and especially Au exhibit a very good degree of crystallinity. We resolve Cu–Cu and Ag–Ag atomic correlations from Au-involving ones in Au–Cu and Au–Ag nanoalloys and show that depending on the synthetic route group 11 binary alloys may adopt structural states that obey or markedly violate Vegard’s law. In the latter case, Cu and Ag atoms undergo substantial size expansion and contraction by as much as 0.3 and 0.03 Å, respectively, while heavier Au atoms remain practically intact. The size change of Cu and Ag atoms does not follow Pauling’s rule of electronegativity predicting charge flow toward the more electronegative Au but occurs in a way such that Cu/Au and Ag/Au atomic size ratios in the nanoalloys become closer to one. Atomic size adjusting and the concurrent charge redistribution result in a synergistic effect of oxygen inactive Au and oxygen very active Cu and Ag leading to nanoalloys with very good activity for low-temperature oxidation of CO

    Resolving Atomic Ordering Differences in Group 11 Nanosized Metals and Binary Alloy Catalysts by Resonant High-Energy X‑ray Diffraction and Computer Simulations

    No full text
    Resonant high-energy X-ray diffraction coupled to atomic pair distribution function analysis and computer simulations is used to study the atomic-scale structure of group 11 nanosized metals and binary alloy catalysts. We find that nanosized Cu is quite disordered structurally whereas nanosized Ag and especially Au exhibit a very good degree of crystallinity. We resolve Cu–Cu and Ag–Ag atomic correlations from Au-involving ones in Au–Cu and Au–Ag nanoalloys and show that depending on the synthetic route group 11 binary alloys may adopt structural states that obey or markedly violate Vegard’s law. In the latter case, Cu and Ag atoms undergo substantial size expansion and contraction by as much as 0.3 and 0.03 Å, respectively, while heavier Au atoms remain practically intact. The size change of Cu and Ag atoms does not follow Pauling’s rule of electronegativity predicting charge flow toward the more electronegative Au but occurs in a way such that Cu/Au and Ag/Au atomic size ratios in the nanoalloys become closer to one. Atomic size adjusting and the concurrent charge redistribution result in a synergistic effect of oxygen inactive Au and oxygen very active Cu and Ag leading to nanoalloys with very good activity for low-temperature oxidation of CO
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