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Invited Article: Tuning and stabilization of optomechanical crystal cavities through NEMS integration
摘要： Nanobeam optomechanical crystals, in which localized GHz frequency mechanical modes are coupled to wavelength-scale optical modes, are being employed in a variety of experiments across different material platforms. Here, we demonstrate the electrostatic tuning and stabilization of such devices, by integrating a Si3N4 slot-mode optomechanical crystal cavity with a nanoelectromechanical systems element, which controls the displacement of an additional 'tuning' beam within the optical near-field of the optomechanical cavity. Under DC operation, tuning of the optical cavity wavelength across several optical linewidths with little degradation of the optical quality factor (Q ≈ 105) is observed. The AC response of the tuning mechanism is measured, revealing actuator resonance frequencies in the 10 MHz–20 MHz range, consistent with the predictions from simulations. Feedback control of the optical mode resonance frequency is demonstrated, and alternative actuator geometries are presented.
关键词： optomechanics,tuning,NEMS,cavity optomechanics,stabilization
更新于2025-09-23 15:22:29
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Adhesion Behavior between Multilayer Graphene and Semiconductor Substrates
摘要： A high bonding strength between graphene and a semiconductor surface is significant to the performance of graphene-based Micro-Electro Mechanical Systems/Nano-Electro Mechanical Systems (MEMS/NEMS) devices. In this paper, by applying a series of constant vertical upward velocities (Vup) to the topmost layer of graphene, the exfoliation processes of multilayer graphene (one to ten layers) from an Si semiconductor substrate were simulated using the molecular dynamics method, and the bonding strength was calculated. The critical exfoliation velocities, adhesion forces, and adhesion energies to exfoliate graphene were obtained. In a system where the number of graphene layers is two or three, there are two critical exfoliation velocities. Graphene cannot be exfoliated when the Vup is lower than the first critical velocity, although the total number of graphene layers can be exfoliated when the Vup is in the range between the first critical velocity and second critical velocity. Only the topmost layer can be exfoliated to be free from the Si surface if the applied Vup is greater than the second critical velocity. In systems where the number of graphene layers is four to ten, only the topmost layer can be free and exfoliated if the exfoliation velocity is greater than the critical velocity. It was found that a relatively low applied Vup resulted in entire graphene layers peeling off from the substrate. The adhesion forces of one-layer to ten-layer graphene systems were in the range of 25.04 nN–74.75 nN, and the adhesion energy levels were in the range of 73.5 mJ/m2–188.45 mJ/m2. These values are consistent with previous experimental results, indicating a reliable bond strength between graphene and Si semiconductor surfaces.
关键词： adhesion force,bonding mechanism,adhesion energy,exfoliation behavior,MEMS/NEMS,molecular dynamics,graphene
更新于2025-09-23 15:19:57
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Giant, Voltage Tuned, Q-factors of Single Wall Carbon Nanotubes and Graphene at Room Temperature
摘要： Mastering dissipation in graphene based nanostructures is still the major challenge in most fundamental and technological exploitations of these ultimate mechanical nanoresonators. Although high quality factors have been measured for carbon nanotubes (> 106) and graphene (> 105) at cryogenic temperatures, room temperature values are orders of magnitude lower ((cid:39) 102). We present here a controlled quality factor increase of up to ×103 for these basic carbon nanostructures when externally stressed like a guitar string. Quantitative agreement is found with theory attributing this decrease in dissipation to the decrease in viscoelastic losses inside the material, an effect enhanced by tunable "soft clamping". Quality factors exceeding 25,000 for SWCNTs and 5000 for graphene were obtained on several samples, reaching the limits of the graphene material itself. The combination of ultra-low size and mass with high quality factors opens new perspectives for atomically localized force sensing and quantum computing as the coherence time exceeds state of the art cryogenic devices.
关键词： Q factor,graphene,carbon nanotube,NEMS,nanomechanics
更新于2025-09-19 17:15:36
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Hexagonal Boron Nitride Phononic Crystal Waveguides
摘要： Hexagonal boron nitride (h-BN), one of the hallmark van der Waals (vdW) layered crystals with an ensemble of attractive physical properties, is playing increasingly important roles in exploring two-dimensional (2D) electronics, photonics, mechanics, and emerging quantum engineering. Here we report on the demonstration of h-BN phononic crystal waveguides with designed pass and stop bands in the radio frequency (RF) range, and controllable wave propagation and transmission, by harnessing arrays of coupled h-BN nanomechanical resonators with engineerable coupling strength. Experimental measurements validate that these phononic crystal waveguides confine and support 15 to 24 megahertz (MHz) wave propagation over hundreds of micrometers. Analogous to solid-state crystal lattices, phononic bandgaps and dispersive behaviors have been observed and systematically investigated in the h-BN phononic waveguides. Guiding and manipulating acoustic waves on such additively integratable h-BN platform may facilitate multiphysical coupling and information transduction, and open up new opportunities for coherent on-chip signal processing and communication via emerging h-BN photonic and phononic devices.
关键词： integrated phononics,phononic crystal waveguide,nanoelectromechanical systems (NEMS),acoustic wave,Hexagonal boron nitride (h-BN),radio frequency
更新于2025-09-19 17:13:59
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Fabrication and Measurement of a Suspended Nanochannel Microbridge Resonator Monolithically Integrated with CMOS Readout Circuitry
摘要： We present the fabrication and characterization of a suspended microbridge resonator with an embedded nanochannel. The suspended microbridge resonator is electrostatically actuated, capacitively sensed, and monolithically integrated with complementary metal-oxide-semiconductor (CMOS) readout circuitry. The device is fabricated using the back end of line (BEOL) layers of the AMS 0.35 μm commercial CMOS technology, interconnecting two metal layers with a contact layer. The fabricated device has a 6 fL capacity and has one of the smallest embedded channels so far. It is able to attain a mass sensitivity of 25 ag/Hz using a fully integrable electrical transduction.
关键词： nanochannel,NEMS,suspended channel,resonators,CMOS-NEMS
更新于2025-09-10 09:29:36
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Optical imaging and image analysis for high aspect ratio NEMS
摘要： A strategy for optical microscopy of high-aspect-ratio (HAR) nanoelectromechanical systems (NEMS) that combine large feature spacing and large height with sub-wavelength width is presented. Line images are simulated using a 2D model of incoherent imaging based on modal diffraction theory. Beyond a sufficient depth, it is shown that sub-wavelength features appear as dark lines, while wider features are visible as their edges. The results suggest NEMS and MEMS may be separated from background in images by detection of valleys in brightness. Results are confirmed by imaging of Si NEMS containing 100 nm wide features in a bright-field microscope. Algorithms for separation of NEMS, MEMS and background in microscope images based on valley detection, thresholding and masking are demonstrated.
关键词： MEMS,image segmentation,NEMS,sub-wavelength imaging
更新于2025-09-10 09:29:36
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[IEEE 2018 Conference on Precision Electromagnetic Measurements (CPEM 2018) - Paris, France (2018.7.8-2018.7.13)] 2018 Conference on Precision Electromagnetic Measurements (CPEM 2018) - Electromagnetic Metrology for NEMS
摘要： This paper outlines how demands on electromagnetic metrology have developed over recent years with the continuing reduction in the typical length scale of electronic components and circuits. In addition novel materials, especially 2D self-supporting structures such as graphene, have properties quite unlike conventional systems. At the nanoscale radical changes occur in techniques required and even in the physical quantities measured. This paper focusses on the example of a near-field scanning microwave microscope and its application to nanoelectromechanical system resonators to illustrate these changes and challenges.
关键词： nanoscale electromagnetic metrology,NEMS,graphene,microwave,NSMM
更新于2025-09-10 09:29:36
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On the numerical investigation of size and surface effects on nonlinear dynamics of a nanoresonator under electrostatic actuation
摘要： This study aims to investigate the influences of nanostructure parameter and surface elasticity parameters on the nonlinear vibration of a nanoelectromechanical system under double-sided electrostatic actuation. For this, the effects of size dependency and surface energy are modeled through applying the consistent couple-stress theory together with the Gurtin–Murdoch elasticity theory. Taking into account the midplane stretching effect for doubly clamped boundary conditions, the nonlinear strain–displacement relationship is considered based on the Euler–Bernoulli beam assumption. Hamilton’s principle is utilized in order to establish the governing differential motion’s equation, and reduced-order model is obtained through implementing Galerkin’s procedure. Bifurcation diagrams are plotted to capture the steady-state response of the system with varying the nondimensional parameter, the ratio of AC to DC voltage amplitude. The influences of the length-scale parameter, surface elasticity modulus and density, and residual surface stress on the system dynamic response have been explored. The results reveal that the pull-in excitation frequency is highly influenced by these parameters, and also the interval length of the bifurcation parameter corresponding to the periodic and chaotic motions is extremely shifted by the amount of couple-stress and residual surface stress parameters.
关键词： Size-dependent NEMS,Chaos,Bifurcation,Surface effects
更新于2025-09-09 09:28:46