Decrease in processing speed due to increased resistance and capacitance delay is a major obstacle for the down-scaling of electronics
. Minimizing the dimensions of interconnects (metal wires that ...connect different electronic components on a chip) is crucial for the miniaturization of devices. Interconnects are isolated from each other by non-conducting (dielectric) layers. So far, research has mostly focused on decreasing the resistance of scaled interconnects because integration of dielectrics using low-temperature deposition processes compatible with complementary metal-oxide-semiconductors is technically challenging. Interconnect isolation materials must have low relative dielectric constants (κ values), serve as diffusion barriers against the migration of metal into semiconductors, and be thermally, chemically and mechanically stable. Specifically, the International Roadmap for Devices and Systems recommends
the development of dielectrics with κ values of less than 2 by 2028. Existing low-κ materials (such as silicon oxide derivatives, organic compounds and aerogels) have κ values greater than 2 and poor thermo-mechanical properties
. Here we report three-nanometre-thick amorphous boron nitride films with ultralow κ values of 1.78 and 1.16 (close to that of air, κ = 1) at operation frequencies of 100 kilohertz and 1 megahertz, respectively. The films are mechanically and electrically robust, with a breakdown strength of 7.3 megavolts per centimetre, which exceeds requirements. Cross-sectional imaging reveals that amorphous boron nitride prevents the diffusion of cobalt atoms into silicon under very harsh conditions, in contrast to reference barriers. Our results demonstrate that amorphous boron nitride has excellent low-κ dielectric characteristics for high-performance electronics.
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FZAB, GEOZS, IJS, IMTLJ, KILJ, KISLJ, MFDPS, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, SBMB, SBNM, UKNU, UL, UM, UPUK, VKSCE, ZAGLJ
Organic–inorganic hybrid perovskites are emerging as promising emitting materials due to their narrow full-width at half-maximum emissions, color tunability, and high photoluminescence quantum yields ...(PLQYs). However, the thermal generation of free charges at room temperature results in a low radiative recombination rate and an excitation-intensity-dependent PLQY, which is associated with the trap density. Here, we report perovskite films composed of uniform nanosized single crystals (average diameter = 31.7 nm) produced by introducing bulky amine ligands and performing the growth at a lower temperature. By effectively controlling the crystal growth, we maximized the radiative bimolecular recombination yield by reducing the trap density and spatially confining the charges. Finally, highly bright and efficient green emissive perovskite light-emitting diodes that do not suffer from electroluminescence blinking were achieved with a luminance of up to 55 400 cd m–2, current efficiency of 55.2 cd A–1, and external quantum efficiency of 12.1%.
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IJS, KILJ, NUK, PNG, UL, UM
A persistent hyaloid artery is a rare fetal remnant. Several complications such as amblyopia, vitreous hemorrhage, and retinal detachment have been reported. Here, we present a case of vitreous ...hemorrhage with a persistent hyaloid artery.
A healthy 16-year-old male presented with blurred vision in his left eye. Vitreous hemorrhage occurred and absorbed spontaneously. Slit-lamp examination demonstrated a Mittendorf's dot and fundus examination revealed a persistent hyaloid artery. Optical coherence tomography (OCT) showed a Bergmeister's papilla. The blood flow of the persistent hyaloid artery via the Bergmeister's papilla was found by OCT angiography.
The persistent hyaloid artery should be considered as a cause of spontaneous vitreous hemorrhage of young healthy patient. The OCT angiography will be a useful noninvasive approach to confirm the patency of the persistent hyaloid artery.
Nanoporous gold (np-Au) samples of ligament sizes 68.6, 248.6, 462.9, and 710.9nm are prepared by heat treatment, and representative volumes are reconstructed by focused ion beam (FIB) tomography. ...The increase in relative density by thermal coarsening is not pronounced. We analyze the distribution of ligament size, surface-to-volume ratio, and scaled connectivity density for coarsened np-Au, revealing that np-Au coarsens in a self-similar way. The measured activation energy for thermal coarsening supports that it is accomplished by surface diffusion of Au.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UL, UM, UPCLJ, UPUK, ZRSKP
Annealed, prestrained, and ball-milled nanoporous gold (np-Au) samples were prepared. Since the microstructures of the precursor alloys, such as the crystallographic orientation and grain size, were ...mostly preserved during the dealloying process, prestrained np-Au is believed to have higher initial dislocation density, and ball-milled np-Au is believed to have higher densities of initial dislocation and grain boundary comparing to annealed np-Au. The time-dependent deformation behavior of np-Au samples with various microstructures was characterized with two parameters; creep strain exponent n and activation volume V∗ using spherical nanoindentation creep tests. We found that primary mechanism of time-dependent plasticity for annealed and prestrained np-Au samples is dislocation slip and that for ball-milled np-Au sample is grain boundary sliding. In dislocation slip-dominant time-dependent deformation in np-Au, a higher initial dislocation density lowers n and V∗. In grain boundary sliding-dominant time-dependent deformation in np-Au, the values of n and V∗ are similar to those for dislocation slip-dominant time-dependent deformation; however, the creep strain rate in quasi-steady-state is higher than that for dislocation slip-dominant time-dependent deformation.
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•Three nanoporous gold (np-Au) samples with different microstructure were fabricated.•Time-dependent plasticity was characterized by spherical nanoindentation creep test.•Primary mechanism of time-dependent plasticity was found to be dependent on the microstructure of np-Au.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UL, UM, UPCLJ, UPUK, ZRSKP
We fabricate nanotubular ZnO with wall thickness of 45, 92, 123 nm using nanoporous gold (np-Au) with ligament diameter at necks of 1.43 μm as sacrificial template. Through micro-tensile and ...micro-compressive testing of nanotubular ZnO structures, we find that the exponent m in Formula: see text, where Formula: see text is the relative strength and Formula: see text is the relative density, for tension is 1.09 and for compression is 0.63. Both exponents are lower than the value of 1.5 in the Gibson-Ashby model that describes the relation between relative strength and relative density where the strength of constituent material is independent of external size, which indicates that strength of constituent ZnO increases as wall thickness decreases. We find, based on hole-nanoindentation and glazing incidence X-ray diffraction, that this wall-thickness-dependent strength of nanotubular ZnO is not caused by strengthening of constituent ZnO by size reduction at the nanoscale. Finite element analysis suggests that the wall-thickness-dependent strength of nanotubular ZnO originates from nanotubular structures formed on ligaments of np-Au.
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IZUM, KILJ, NUK, PILJ, PNG, SAZU, UL, UM, UPUK
Nanoporous gold with a hierarchical structure has prospects as an advanced functional material with enhanced mechanical properties, but how the hierarchical structure affects its mechanical ...properties compared to a unimodal structure has not been revealed. Here, we investigate the mechanical behavior of hierarchically-structured nanoporous gold and unimodally-structured nanoporous gold with the same relative density by micropillar compressive tests in dry and electrolyte environment. The ligament size at the upper-level structure in hierarchically-structured nanoporous gold and the ligament size in unimodally-structured nanoporous gold are kept similar, while having hierarchically-structured samples with ligament sizes of 10 to 50 nm at lower-level structure. We find that hierarchically-structured nanoporous gold shows greater compressive strength and pronounced stress-variation by oxidization of the surface compared to unimodally-structured nanoporous gold. A ligament-size dependency on the lower-level structure in hierarchical samples is observed, with compressive strength and stress variation by surface oxidation increasing as the lower-level ligament size decreases. Three-dimensionally reconstructed structure analysis suggests that the enhanced mechanical properties of hierarchically-structured nanoporous gold are attributed to the better-connected network of ligaments originating from two separated dealloying-coarsening procedures. The influence of dislocation activities depending on characteristic sizes is also discussed to elucidate the distinguished mechanical behavior.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
Tensile and compressive tests are carried out on four nanoporous gold samples with ligament sizes of 56, 149, 402, and 868 nm, all without grain boundaries and with similar number of ligaments ...regardless of ligament size. We find that tensile yield strengths are greater than compressive yield strengths up to ligament size of 402 nm, while yield strengths are similar in tension and compression for dL of 868 nm. The dependence of tensile yield strength on ligament size is described well using a size-effect exponent -1.18 for four samples, whereas bulk-like behavior, i.e. no ligament-size dependency, is observed for ligament size greater than 402 nm in compression; compressive yield strength depending on ligament size is described by a size-effect exponent -1.49 for ligament sizes ranging from 56 nm to 402 nm. The asymmetries in yield strength and plasticity between tension and compression are discussed in terms of the deformation behavior of individual ligaments based on a suggested open-cell model and dislocation activities in the ligaments.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
Enhanced resistance to crack propagation in nanoporous gold (np-Au) with fine grains is observed comparing with conventional np-Au with coarse grains. Cyclic hot-rolling is adopted to prepare fine ...grain structure in Au-Ag precursor alloys, which evolve to fine grained np-Au with grain size of 3.69 µm after dealloying. Np-Au with fine grains exhibits stable crack growth with enhanced stress intensity for crack propagation KJc of 0.133 MPa∙m1/2 while np-Au with coarse grains shows linear elastic fracture behavior with stress intensity factor for crack initiation KIc of 0.042 MPa∙m1/2. Enhanced crack resistance in fine grained np-Au is achieved with intergranular fracture, which is attributed to the effective strain energy release through grain boundary plasticity.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UL, UM, UPCLJ, UPUK, ZRSKP
10.
Moving wetting ridges on ultrasoft gels Jeon, Hansol; Chao, Youchuang; Karpitschka, Stefan
Physical review. E,
08/2023, Volume:
108, Issue:
2
Journal Article
Peer reviewed
Open access
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CMK, CTK, FMFMET, IJS, NUK, PNG, UM
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