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Repulsive magnetic field–assisted laser-induced plasma micromachining for high-quality microfabrication
摘要： Surface micro-/nanostructures are widely used in the fabrication of various functional microsystems. Laser-induced plasma micromachining can greatly improve surface quality in terms of recast layers and thermal defects compared with laser direct writing. Magnetic field has the ability to constrain plasma diffusion and can ensure the stability of laser-induced plasma processing. This paper compares the effects of laser direct–writing processing and laser-induced plasma processing of single-crystal silicon at the micro-/nanoscale, and emphatically analyzes the material removal mechanism of repulsive magnetic field–assisted laser-induced plasma micromachining. It is shown that the volume of the laser-induced plasma was constrained under the influence of Lorentz force, a high-quality smooth microgroove without thermal defects was obtained, and its line width was reduced by 30%.
关键词： Laser-induced plasma micromachining,Magnetic confinement,Thermal defects,Micro-/nanofabrication
更新于2025-11-21 11:24:58
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Nondestructive nanofabrication on monocrystalline silicon via site-controlled formation and removal of oxide mask
摘要： A nondestructively patterned silicon substrate serves as an ideal support for forming high-quality optical structures or devices. A new approach was proposed for fabricating site-controlled structures without destruction on a monocrystalline silicon surface via local anodic oxidation (LAO) and two-step postetching. The nondestruction was demonstrated by conductivity detection with conductive atomic force microscopy (AFM), and an almost perfect crystal lattice was observed from the fabricated hillock by high-resolution transmission electron microscopy (HRTEM). By programming AFM tip traces for LAO processing, site-controlled nondestructive patterns with di?erent layouts can be produced. This approach provides a new route for realizing nondestructive optical substrates.
关键词： conductive atomic force microscopy,high-resolution transmission electron microscopy,local anodic oxidation,nondestructive nanofabrication,monocrystalline silicon
更新于2025-11-14 17:04:02
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Interfacial Contact is Required for Metal-Assisted Plasma Etching of Silicon
摘要： For decades, fabrication of semiconductor devices has utilized well-established etching techniques to create complex nanostructures in silicon. The most common dry process is reactive ion etching which fabricates nanostructures through the selective removal of unmasked silicon. Generalized enhancements of etching have been reported with mask-enhanced etching with Al, Cr, Cu, and Ag masks, but there is a lack of reports exploring the ability of metallic films to catalytically enhance the local etching of silicon in plasmas. Here, metal-assisted plasma etching (MAPE) is performed using patterned nanometers-thick gold films to catalyze the etching of silicon in an SF6/O2 mixed plasma, selectively increasing the rate of etching by over 1000%. The catalytic enhancement of etching requires direct Si-metal interfacial contact, similar to metal-assisted chemical etching (MACE), but is different in terms of the etching mechanism. The mechanism of MAPE is explored by characterizing the degree of enhancement as a function of Au catalyst configuration and relative oxygen feed concentration, along with the catalytic activities of other common MACE metals including Ag, Pt, and Cu.
关键词： nanofabrication,MACE,silicon processing,reactive ion etching,metal assisted etching
更新于2025-09-23 15:23:52
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Ultrahigh- <i>Q</i> Photonic Nanocavity Devices on a Dual Thickness SOI Substrate Operating at Both 1.31- and 1.55-μm Telecommunication Wavelength Bands
摘要： A feasible method for integrating several silicon (Si) photonic devices with operating wavelengths separated by several hundred nanometers on a single chip will greatly help increasing capacities of small optical communication modules. This work demonstrates the integration of two photonic crystal nanocavity devices that exhibit ultrahigh quality factors (Q) and operate at the 1.31- and 1.55-μm bands. A dual thickness Si-on-insulator substrate forms the base of the device. The two nanocavity patterns are defined by electron beam lithography on the thick and thin substrate regions and are transferred to the top Si layer by performing plasma etching only once. All dimensions of the fabricated 1.31-μm nanocavity are (cid:2)15.5% smaller (1–1.31/1.55) than those of the 1.55-μm nanocavity; that is, they can be treated with the same photonic band diagram. Both nanocavities exhibit an ultrahigh Q > 2.0 × 106 and enable fabrication of nanocavity-based Raman lasers for the 1.31/1.55-μm bands with sub-microwatt threshold.
关键词： nanofabrication,microcavity,Raman Si laser,photonic crystal
更新于2025-09-23 15:23:52
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Nanofluidic and monolithic environmental cells for cryogenic microscopy
摘要： We present a device capable of combining nanofluidics and cryogenic transmission electron microscopy (cryo-TEM) to allow inspection of water-soluble samples under near-native conditions. The devices can be produced in a multitude of designs, but as a general rule, they consist of channels or chambers enclosed between two electron-transparent silicon nitride windows. With the appropriate design, those devices can allow screening of multiple samples in parallel and remove the interaction between the sample and the environment (no air–water interface). We demonstrate channel sizes from 80 to 500 nm in height and widths from 100 to 2000 μm. The presented fabrication flow allows producing hollow devices on a single wafer eliminating the need of aligning or bonding two half-cavities from separate wafers, which provides additional resistance to thermal stress. Taking advantage of a single-step through-membrane exposure with a 100 keV electron beam, we introduced arrays of thin (10–15 nm) electron-transparent silicon nitride membrane windows aligned between top and bottom (200–250 nm) carrier membranes. Importantly, the final devices are compatible with standard TEM holders. Furthermore, they are compatible with rapid freezing of samples, which is crucial for the formation of vitreous water, hence avoiding the formation of crystalline ice, that is detrimental for TEM imaging. To demonstrate the potential of this technology, we tested those devices in imaging experiments verifying their applicability for cryo-TEM applications and proved that vitreous water could be prepared through conventional plunge freezing of the chips.
关键词： nanofabrication,TEM,environmental chamber,microfluidic cell,electron beam lithography,cryo-TEM
更新于2025-09-23 15:23:52
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[IEEE 2018 IEEE International Conference on Manipulation, Manufacturing and Measurement on the Nanoscale (3M-NANO) - Hangzhou, China (2018.8.13-2018.8.17)] 2018 IEEE International Conference on Manipulation, Manufacturing and Measurement on the Nanoscale (3M-NANO) - Nanofabrication Techniques Used for Suppressing Multipactor in Space Applications
摘要： A significant trouble in high power microwave (HPM) systems is multipactor discharge – an avalanche of electrons resulting from the secondary electron emission (SEE). It would cause serious problems and limits the attainable power. Nano fabrication techniques, such as sputtering, photolithography, etching and Graphene, are adopted to reduce the secondary electron yield (SEY) of a material to improve multipactor discharge threshold. It is clearly demonstrated that these fabrications can suppress the SEY efficiently. The influence of surface characteristic on SEY is discussed to find that increase porosity and aspect ratio will reduce SEY. These results provided a criterion to determine nanofabrication techniques for multipactor suppression.
关键词： nanofabrication techniques,secondary electron emission,suppression,multipactor
更新于2025-09-23 15:23:52
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Low-cost light manipulation coatings for polymer solar cell photocurrent increase under various incident angles
摘要： We fabricate self-assembled templates to produce textured polydimethylsiloxane (PDMS) with quasi-random dimension distributions which are employed as light manipulation coatings in polymer solar cells (PSCs). When deposited at the PSC glass/air interface, PDMS films with microdome-like structures enhance the short-circuit current density (Jsc) by 7.9% through combined anti-reflective and scattering effects. The PSC power conversion efficiency can thus be improved from 6.75% to 7.28% and a maximum Jsc increase of 21% is observed for incident light tilted by 30 degrees. We compare structures with different diameter dispersities and confirm that quasi-randomness in textured coatings can increase their light scattering ability.
关键词： Nanofabrication,self-assembly,light manipulation,polymer solar cells
更新于2025-09-23 15:22:29
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Photothermally Assisted Thinning of Silicon Nitride Membranes for Ultrathin Asymmetric Nanopores
摘要： Sculpting solid-state materials at the nanoscale is an important step in manufacturing of numerous types of sensor devices, in particular solid-state nanopore sensors. Here we present mechanistic insight into laser-induced thinning of low-stress silicon nitride (SiNx) membranes and films. In a recent study, we observed that focusing a visible wavelength laser beam on a SiNx membrane results in efficient localized heating, and used this effect to control temperature at a solid-state nanopore sensor. A side-effect of the observed heating was that the pores expand/degrade under prolonged high-power illumination, prompting us to study the mechanism of this etching process. We find that SiNx can be etched under exposure to light of ~107 W/cm2 average intensity, with etch rates that are influenced by the supporting electrolyte. Combining this controlled etching with dielectric breakdown, an electrokinetic process for making pores, nanopores of arbitrary dimensions as small as 1-2 nm in diameter and thickness can easily be fabricated. Evidence gathered from biomolecule-pore interactions suggests that the pore geometries obtained using this method are more funnel-like, rather than hourglass-shaped. Refined control over pore dimensions can expand the range of applications of solid-state nanopores, for example, biopolymer sequencing and detection of specific biomarkers.
关键词： photothermal heating,single-molecule,dielectric breakdown,Nanopores,nanofabrication
更新于2025-09-23 15:21:21
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Block Copolymer Derived Vertically Coupled Plasmonic Arrays for Surface-Enhanced Raman Spectroscopy
摘要： A surface-enhanced Raman spectroscopy sensing template consisting of gold-covered nanopillars is developed. The plasmonic slab consists of a perforated gold film at the base of the nanopillars and a Babinet complementary dot array on top of the pillars. The nanopillars were fabricated by the incorporation of an iron salt precursor into a self-assembled block copolymer thin film and subsequent reactive ion etching. The preparation is easy, scalable, and cost-effective. We report on the increase in surface-enhanced Raman scattering efficiency for smaller pillar heights and stronger coupling between the dot array and perforated gold film with average enhancement factors as high as 107. In addition, the block copolymer-derived templates show an excellent relative standard deviation of 8% in the measurement of the Raman intensity. Finite difference time domain simulations were performed to investigate the nature of the electromagnetic near-field enhancement and to identify plasmonic hot spots.
关键词： block copolymer lithography,finite difference time domain simulation,SERS uniformity,plasmonic nanomaterials,surface-enhanced Raman spectroscopy,nanofabrication,4-aminothiophenol
更新于2025-09-23 15:21:01
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A Gas Sensor Based on a Single SnO Micro-Disk
摘要： In this study, individual nanofabricated SnO micro-disks, previously shown to exhibit exceptional sensitivity to NOx, are investigated to further our understanding of gas sensing mechanisms. The SnO disks presenting different areas and thickness were isolated and electrically connected to metallic electrodes aided by a Dual Beam Microscope (SEM/FIB). While single micro-disk devices were found to exhibit short response and recovery times and low power consumption, large interconnected arrays of micro-disks exhibit much higher sensitivity and selectivity. The source of these differences is discussed based on the gas/solid interaction and transport mechanisms, which showed that thickness plays a major role during the gas sensing of single-devices. The calculated Debye length of the SnO disk in presence of NO2 is reported for the first time.
关键词： single-element device,FIB nanofabrication,low power consumption,semiconductor,sensing mechanism,Debye length,gas sensor,SnO
更新于2025-09-23 15:21:01