10 research outputs found
Lattice Registry and Evidence for Surface Reconstructions of Metal Films on Suspended 2D Membranes Following Annealing
Fabrication of short-wavelength photonic crystals in wide-band-gap nanocrystalline diamond films
Acoustic cavities in 2D heterostructures
Two-dimensional (2D) materials offer unique opportunities in engineering the ultrafast spatiotemporal response of composite nanomechanical structures. In this work, we report on high frequency, high quality factor (Q) 2D acoustic cavities operating in the 50–600 GHz frequency (f) range with f × Q up to 1 × 10(14). Monolayer steps and material interfaces expand cavity functionality, as demonstrated by building adjacent cavities that are isolated or strongly-coupled, as well as a frequency comb generator in MoS(2)/h-BN systems. Energy dissipation measurements in 2D cavities are compared with attenuation derived from phonon-phonon scattering rates calculated using a fully microscopic ab initio approach. Phonon lifetime calculations extended to low frequencies (<1 THz) and combined with sound propagation analysis in ultrathin plates provide a framework for designing acoustic cavities that approach their fundamental performance limit. These results provide a pathway for developing platforms employing phonon-based signal processing and for exploring the quantum nature of phonons
Engineering Graphene Mechanical Systems
We report a method to introduce direct bonding between
graphene
platelets that enables the transformation of a multilayer chemically
modified graphene (CMG) film from a “paper mache-like”
structure into a stiff, high strength material. On the basis of chemical/defect
manipulation and recrystallization, this technique allows wide-range
engineering of mechanical properties (stiffness, strength, density,
and built-in stress) in ultrathin CMG films. A dramatic increase in
the Young’s modulus (up to 800 GPa) and enhanced strength (sustainable
stress ≥1 GPa) due to cross-linking, in combination with high
tensile stress, produced high-performance (quality factor of 31 000
at room temperature) radio frequency nanomechanical resonators. The
ability to fine-tune intraplatelet mechanical properties through chemical
modification and to locally activate direct carbon–carbon bonding
within carbon-based nanomaterials will transform these systems into
true “materials-by-design” for nanomechanics
Engineering Graphene Mechanical Systems
We report a method to introduce direct bonding between
graphene
platelets that enables the transformation of a multilayer chemically
modified graphene (CMG) film from a “paper mache-like”
structure into a stiff, high strength material. On the basis of chemical/defect
manipulation and recrystallization, this technique allows wide-range
engineering of mechanical properties (stiffness, strength, density,
and built-in stress) in ultrathin CMG films. A dramatic increase in
the Young’s modulus (up to 800 GPa) and enhanced strength (sustainable
stress ≥1 GPa) due to cross-linking, in combination with high
tensile stress, produced high-performance (quality factor of 31 000
at room temperature) radio frequency nanomechanical resonators. The
ability to fine-tune intraplatelet mechanical properties through chemical
modification and to locally activate direct carbon–carbon bonding
within carbon-based nanomaterials will transform these systems into
true “materials-by-design” for nanomechanics
Engineering Graphene Mechanical Systems
We report a method to introduce direct bonding between
graphene
platelets that enables the transformation of a multilayer chemically
modified graphene (CMG) film from a “paper mache-like”
structure into a stiff, high strength material. On the basis of chemical/defect
manipulation and recrystallization, this technique allows wide-range
engineering of mechanical properties (stiffness, strength, density,
and built-in stress) in ultrathin CMG films. A dramatic increase in
the Young’s modulus (up to 800 GPa) and enhanced strength (sustainable
stress ≥1 GPa) due to cross-linking, in combination with high
tensile stress, produced high-performance (quality factor of 31 000
at room temperature) radio frequency nanomechanical resonators. The
ability to fine-tune intraplatelet mechanical properties through chemical
modification and to locally activate direct carbon–carbon bonding
within carbon-based nanomaterials will transform these systems into
true “materials-by-design” for nanomechanics