Understanding the interaction between energetic ions and freestanding graphene towards practical 2D perforation

We report experimentally and theoretically the behavior of freestanding graphene subject to bombardment of energetic ions, investigating the ability of large-scale patterning of freestanding graphene with nanometer sized features by focused ion beam technology. A precise control over the He+ and Ga+ irradiation offered by focused ion beam techniques enables to investigate the interaction of the energetic particles and graphene suspended with no support and allows determining sputter yields of the 2D lattice. We find strong dependency of the 2D sputter yield on the species and kinetic energy of the incident ion beams. Freestanding graphene shows material semi-transparency to He+ at high energies (10-30 keV) allowing the passage of >97% He+ particles without creating destructive lattice vacancy. Large Ga+ ions (5-30 keV), in contrast, collide far more often with the graphene lattice to impart significantly higher sputter yield of ~50%. Binary collision theory applied to monolayer and few-layer graphene can successfully elucidate this collision mechanism, in great agreement with experiments. Raman spectroscopy analysis corroborates the passage of a large fraction of He+ ions across graphene without much damaging the lattice whereas several colliding ions create single vacancy defects. Physical understanding of the interaction between energetic particles and suspended graphene can practically lead to reproducible and efficient pattern generation of unprecedentedly small features on 2D materials by design, manifested by our perforation of sub-5-nm pore arrays. This capability of nanometer scale precision patterning of freestanding 2D lattices shows practical applicability of the focused ion beam technology to 2D material processing for device fabrication and integration.Comment: 31 pages of main text (with 4 figures) plus 4 pages of supporting information (with 2 figures). Original article submitted to a journal for consideration for publicatio

Technologieentwicklung und -unterstützung für Ionenfallenbasierte Quantencomputer (TeufIQ)

Purpose of the TeufIQ project is to support the industrial partners of QC-I in developing and manufacturing prototypes of ion-trap based quantum computers. The project framework encompasses a wide range of research services for the QC-I partners placed at the Innovation Center Hamburg (IZHH). The project’s foundation is the expertise and the experience in micro- and nanotechnology of the DLR division QT-IMN in Ulm. We particularly address close collaboration working on open research questions and the development of related technological solutions to facilitate the production of ion-trap based quantum computers in future

Draft Nuclear Genome Sequence of the Halophilic and Beta-Carotene- Accumulating Green Alga Dunaliella salina Strain CCAP19/18

The halotolerant alga Dunaliella salina is a model for stress tolerance and is used commercially for production of beta-carotene (pro-vitamin A). The presented draft genome of the genuine strain CCAP19/18 will allow investigations into metabolic processes involved in regulation of stress responses, including carotenogenesis and adaptations to life in high-salinity environments

StarQ - Surface treatment at atomic resolution for Quantum Computing

Quantencomputer auf Basis von Stickstoff-Fehlstellen (sog. NV-Zentren) haben ein sehr großes Potential. Eine große Herausforderung ist jedoch die noch unzureichende Kontrolle über die Diamantoberfläche. Besonders geätzte oder polierte Oberflächen besitzen Defekte, welche die Qubits empfindlich stören können. In enger Zusammenarbeit mit Auftragnehmern der QC-I am DLR-Innovationszentrum Ulm möchten wir neuartige Ätz-, Terminierungs- und Beschichtungsprozesse für Diamantoberflächen entwickeln, die ungewollte Defekte verhindern und den Störeinfluss der Diamantoberfläche auf die Qubits minimiert

Failure Mechanism of the Polymer Infiltration of Carbon Nanotube Forests

Polymer melt infiltration is one of the feasible methods for manufacturing filter membranes out of carbon nanotubes (CNTs) on large scales. Practically, however, its process suffers from low yields, and the mechanism behind this failure is rather poorly understood. Here, we investigate a failure mechanism of polymer melt infiltration of vertical aligned (VA-) CNTs. In penetrating the VA-CNT interstices, polymer melts exert a capillarity-induced attractive force laterally on CNTs at the moving meniscus, leading to locally agglomerated macroscale bunches. Such a large configurational change can deform and distort individual CNTs so much as to cause buckling or breakdown of the alignment. In view of membrane manufacturing, this irreversible distortion of nanotubes is detrimental, as it could block the transport path of the membranes. The failure mechanism of the polymer melt infiltration is largely attributed to steric hindrance and an energy penalty of confined polymer chains. Euler beam theory and scaling analysis affirm that CNTs with low aspect ratio, thick walls and sparse distribution can maintain their vertical alignment. Our results can enrich a mechanistic understanding of the polymer melt infiltration process and offer guidelines to the facile large-scale manufacturing of the CNT-polymer filter membranes.11Nsciescopu

Understanding the interaction between energetic ions and freestanding graphene towards practical 2D perforation

We report experimentally and theoretically the behavior of freestanding graphene subject to bombardment of energetic ions, investigating the ability of large-scale patterning of freestanding graphene with nanometer sized features by focused ion beam technology. A precise control over the He+ and Ga+ irradiation offered by focused ion beam techniques enables to investigate the interaction of the energetic particles and graphene suspended with no support and allows determining sputter yields of the 2D lattice. We find strong dependency of the 2D sputter yield on the species and kinetic energy of the incident ion beams. Freestanding graphene shows material semi-transparency to He+ at high energies (10-30 keV) allowing the passage of >97% He+ particles without creating destructive lattice vacancy. Large Ga+ ions (5-30 keV), in contrast, collide far more often with the graphene lattice to impart significantly higher sputter yield of ~50%. Binary collision theory applied to monolayer and few-layer graphene can successfully elucidate this collision mechanism, in great agreement with experiments. Raman spectroscopy analysis corroborates the passage of a large fraction of He+ ions across graphene without much damaging the lattice whereas several colliding ions create single vacancy defects. Physical understanding of the interaction between energetic particles and suspended graphene can practically lead to reproducible and efficient pattern generation of unprecedentedly small features on 2D materials by design, manifested by our perforation of sub-5-nm pore arrays. This capability of nanometer scale precision patterning of freestanding 2D lattices shows practical applicability of the focused ion beam technology to 2D material processing for device fabrication and integration

Architecture and Transport Properties of Membranes out of Graphene

22Nkc

Analysis of the tensile response of a stranded conductor using a 3D finite element model

ISSN:0020-740