Nanolithography Technique Research Articles

Far-field femtosecond laser-driven λ/73 super-resolution fabrication of 2D van der Waals NbOI2 nanostructures in ambient air

The design and fabrication of ultrafine nanostructures in two-dimensional (2D) van der Waals materials are crucial for the functionalization of electronic devices. Here, we report the utilization of far-field femtosecond laser patterning to fabricate super-resolution nano-groove array (NGA) structures in 2D multilayer NbOI2 in ambient air, achieving groove widths as low as ~14.5 nm (~λ/73). The NGA structures maintain a well-defined single-crystal NbOI2 with amorphous Nb2O5 edges as narrow as 3.2 nm. The formation mechanism of NGA structure is confirmed to be associated with the coupled field of surface plasmon polariton periodic field and nano-groove-induced local near-field induced by femtosecond laser irradiation. Furthermore, the NGA-NbOI2 gas sensor exhibits NO2 sensing performance, with a rapid response time (5.1 s), which is attributed to the existence of abundant NbOI2-Nb2O5 heterojunctions. This approach will propel the further development of nano-lithography techniques for functional device applications of 2D materials.

Rapid Assembly of Block Copolymer Thin Films via Accelerating the Swelling Process During Solvent Annealing.

Block copolymer (BCP) lithography is widely regarded as a promising next-generation nanolithography technique. However, achieving rapid assembly with defect-free morphology remains a significant challenge for its practical application. In this study, we presented a facile and efficient solvent annealing method for fabricating well-ordered BCP thin films within minutes on both flat and topographically patterned substrates. By accelerating the swelling process, rapid film swelling was observed within just 10 s of annealing, leading to well-ordered morphologies in 1~3 min. Furthermore, we systematically investigated the influence of swelling ratio (SR) on film morphology by precisely tuning solvent vapor pressure. For cylinder-forming poly(styrene-block-2-vinylpyridine) (PS-b-P2VP) films, we identified three distinct SR-dependent ordering regimes: (I) Excessive SR led to a disordered morphology; (II) near-optimal SR balanced long-range and short-range orders, and a slight increase in SR enhanced the long-range order but introduced short-range defects. (III) Insufficient SR failed to provide adequate chain mobility, limiting long-range order development. These findings highlight the critical role of SR in controlling defect density in nanopatterned surfaces. Long-range-ordered BCP nanopatterns can only be achieved under optimal SR conditions that ensure sufficient chain mobility. We believe this rapid annealing strategy, which is also applicable to other solvent-based annealing systems for BCP films, may contribute to next-generation nanolithography for microfabrication.

Plasmonic smart contact lens based on etalon nanostructure for tear glucose sensing

Smart contact lenses, one of the most advanced wearable platforms, offer a combination of optical and electronic technologies that provide exceptional capabilities in various fields. These lenses are equipped with biosensors, microchips, and sometimes even miniature displays that enable the collection and analysis of biological and environmental data. Smart contact lenses represent a big leap in wearable technology and biosensors, potentially providing a new future for human interaction with the digital world, improving personal health, and promising a hopeful future in vision and wearable technologies. In this study, smart contact lenses based on plasmonic etalon nanostructure have been proposed and fabricated for tear glucose sensing. A cost-effective and simple technique of soft nanolithography has been proposed to fabricate a plasmonic sensor chip on a contact lens, enabling the detection of glucose solutions at different concentrations of 0.15, 1.5, 5, and 10 mM in a phosphate-buffered saline (PBS) solution. The proposed plasmonic etalon-based smart contact lens as a wearable platform exhibits the capacity to sense tear glucose (even at low concentration values) and offers relatively high sensitivity for non-invasive tear glucose sensing applications. The biocompatibility, cost-effectiveness, stability, and simple production of these contact lenses may provide new perspectives on wearable biosensors.

Diffractive lenses for neutron techniques

Many neutron techniques can greatly benefit from enhanced neutron lenses for focusing and imaging. In this work, we revisit the potential of diffractive optics for neutron beams, building on advanced high-resolution nano-lithography techniques developed for the fabrication of X-ray diffractive optics used at synchrotron facilities. We demonstrate state-of-the-art fabrication of nickel and silicon Fresnel zone plates and we report proof-of-concept experiments for full-field neutron microscopy and small angle neutron scattering. The advancement of neutron diffractive optics will open new opportunities for neutron techniques, improving both the efficiency and resolution of existing instruments.

Burst Laser-Driven Plasmonic Photochemical Nanolithography of Silicon with Active Structural Modulation

Femtosecond laser ablation-driven periodic surface structuring offers a promising method for large-scale and high-throughput nanolithography technique. However, the self-organized periodic structures typically manifest constraints in terms of tunable period and depth, as well as suboptimal regularity, which restricts their broader application potential. Here, in terms of a rarely explored laser-induced photochemical mechanism for nonablative structuring, we demonstrate manufacturing of sub-wavelength oxidative grating structures on silicon films with active structural modulation. In this scenario, the plasmonic field plays a pivotal role in dragging oxygen ions from surface into the silicon, greatly speeding up oxidation rates. While high oxygen doping levels can already be achieved with single-pulse exposure, far superior results are obtained with the application of 40-MHz burst mode pulse trains, mitigating the formation of excessively large nanocrystallites. Furthermore, it is revealed that the periodicity and modulation depth of laser-writing nanograting are both dependent on the number of pulse per burst. This offers a convenient scheme for actively controlling laser plasmonic lithography.

Interaction of Acoustic Waves With Spin Waves Using a GHz Operating GaN/Si SAW Device With a Ni/NiFeSi Layer Between Its IDTs.

A two-port surface acoustic wave (SAW) device was developed to be used for the control and excitation via spin waves (SWs). The structure was manufactured using advanced nanolithography techniques, on GaN/Si, enabling fundamental Rayleigh interdigitated transducer (IDT) resonances in the GHz frequency range. The ferromagnetic resonance (FMR) of the magnetostrictive Ni/NiFeSi layer placed between the IDTs of the SAW device can be tuned to the SAW resonance frequency by magnetic fields. Using structures with finger and interdigit spacing of 170 and 100 nm, fundamental Rayleigh IDT resonance frequencies of 6.4 and 10.4 GHz have been obtained. Coupling of SAW to SW was demonstrated through transmission measurements at the fundamental Rayleigh frequencies in a magnetic field, H from -280 to +280 mT, at different angles ( between the SAW propagation direction and the magnetic field direction. For the 6.4-GHz resonator, a maximum decrease of about 1.2 dB occurred in S , at H =30 mT and at . Time-gated processing of the frequency domain (FD) raw data was used to remove the direct electromagnetic crosstalk and triple transit effects. Nonreciprocity associated with the coupling was analyzed for the two SAW structures. The quantitative influence of the magnetic field strength on the phase of the transmission parameters is also presented.

Asymmetric [Dy2] molecules deposited into micro-SQUID susceptometers: in situ characterization of their magnetic integrity.

The controlled integration of magnetic molecules into superconducting circuits is key to developing hybrid quantum devices. Herein, we study [Dy2] molecular dimers deposited into micro-SQUID susceptometers. The results of magnetic, heat capacity and magnetic resonance experiments, backed by theoretical calculations, show that each [Dy2] dimer fulfills the main requisites to encode a two-spin quantum processor. Arrays of between 2 × 108 and 7 × 109[Dy2] molecules were optimally integrated under ambient conditions inside the 20 μm wide loops of micro-SQUID sensors by means of dip-pen nanolithography. Equilibrium magnetic susceptibility and phonon-assisted spin tunneling dynamics measured in situ substantiate that these molecules preserve spin ground states, magnetic interactions and magnetic asymmetry that characterize them in bulk. These results show that it is possible to interface multi-qubit molecular complexes with on-chip superconducting circuits without disturbing their relevant properties and suggest the potential of soft nanolithography techniques to achieve this goal.

Review of: "the focused ion beam nanolithography technique , deposits can be grown with high lateral resolution"

Review of: "the focused ion beam nanolithography technique , deposits can be grown with high lateral resolution"

High‐Precision Materials Printer for Fast Prototyping of Electronic Devices Based on 2D Materials

AbstractThere is an increasing interest in printed electronics driven principally by flexible and wearable applications. The interest stems from the ability to fabricate electronic devices, such as Field Effect Transistors (FET), more efficiently in terms of materials use and cost‐effectively than traditional lithographic techniques. Challenges persist in achieving high resolution and accuracy in defining device geometry. In the study, a high‐resolution materials printer able to achieve resolutions in the micron range, surpassing the capabilities of commercially available printers is successfully designed and fabricated. The printer incorporates an all‐in‐one printing system, comprising Inkjet and a Dip Pen Nanolithography (DPN) technique, enabling both additive and subtractive manufacturing at the microscale. The experiments demonstrate the successful fabrication of FETs based on 2D materials (2DMs), with micrometric channel lengths exhibiting a high degree of controllability and repeatability, even when contacting limited channel regions as micrometer‐sized molybdenum disulfide (MoS2) flakes. Electrical characterizations of the fabricated devices underscore the significant technological advancements achieved by the prototypes.

Template-assisted growth of Ga-based nanoparticle clusters on Si: effect of post-annealing process on the Ga ion beam exposed 2D arrays fabricated by focused ion beam nanolithography

We demonstrate template-assisted growth of gallium-based nanoparticle clusters on silicon substrate using a focused ion beam (FIB) nanolithography technique. The nanolithography counterpart of the technique steers a focussed 30 kV accelerated gallium ion beam on the surface of Si to create template patterns of two-dimensional dot arrays. Growth of the nanoparticles is governed by two vital steps namely implantation of gallium into the substrate via gallium beam exposure and formation of the stable nanoparticles on the surface of the substrate by subsequent annealing at elevated temperature in ammonia atmosphere. The growth primarily depends on the dose of implanted gallium which is in the order of 107 atoms per spot and it is also critically influenced by the temperature and duration of the post-annealing treatment. By controlling the growth parameters, it is possible to obtain one particle per spot and particle densities as high as 109 particles per square centimetre could be achieved in this case. The demonstrated growth process, utilizing the advantages of FIB nanolithography, is categorized under the guided organization approach as it combines both the classical top-down and bottom-up approaches. Patterned growth of the particles could be utilized as templates or nucleation sites for the growth of an organized array of nanostructures or quantum dot structures.

Review of: "Focused ion beam nanolithography , as a sequential nanolithography technique, is inherently slow and its throughput is much lower than other techniques, and Ga + -based liquid metal ion source"

Review of: "Focused ion beam nanolithography , as a sequential nanolithography technique, is inherently slow and its throughput is much lower than other techniques, and Ga + -based liquid metal ion source"

Review of: "the focused ion beam nanolithography technique , deposits can be grown with high lateral resolution , but with much less damage caused to the substrate due to the low linear motion of electrons compared to ions"

In the focused ion beam nanolithography technique, deposits can be grown with high lateral resolution, but with much less damage caused to the substrate due to the low linear motion of electrons compared to ions. In contrast, the growth rate and metal content of the deposits are generally used for focused ion beam nanolithography. Note: Oligophenylene vanillin (silicon/germanium) structures, nanowires, and cylinders are used for possible applications in energy, electronics, optics, and other fields. Silicon / Germanium Gi), narrow structures whose diameter is only a few billionths of a meter but thousands or millions of times longer, exist in various forms-made of metals, semiconductors, insulators, and organic compounds-and are used for applications in the fields of electronics, energy conversion, optics, and chemical sensing. Because of their extreme thinness, oligophenylene vanillin nanowires with a (Si Silicon / Germanium Gi) structure are essentially one-dimensional. Nanowires are quasi-onedimensional materials; "their two dimensions are on the nanometer scale." This one-dimensionality confers distinct electrical and optical properties. For one thing, this means that the electrons and photons in these nanowires experience "confined quantum effects." However, unlike other materials that produce such quantum effects, such as quantum dots, the length of oligophenylene vanillin nanowires allows them to communicate with other macroscopic devices and the outside world.

Calligraphy of Nanoplasmonic Bioink-Based Multiplex Immunosensor for Precision Immune Monitoring and Modulation.

Immunomodulation therapies have attracted immense interest recently for the treatment of immune-related diseases, such as cancer and viral infections. This new wave of enthusiasm for immunomodulators, predominantly revolving around cytokines, has spurred emerging needs and opportunities for novel immune monitoring and diagnostic tools. Considering the highly dynamic immune status and limited window for therapeutic intervention, precise real-time detection of cytokines is critical to effectively monitor and manage the immune system and optimize the therapeutic outcome. The clinical success of such a rapid, sensitive, multiplex immunoanalytical platform further requires the system to have ease of integration and fabrication for sample sparing and large-scale production toward massive parallel analysis. In this article, we developed a nanoplasmonic bioink-based, label-free, multiplex immunosensor that can be readily "written" onto a glass substrate via one-step calligraphy patterning. This facile nanolithography technique allows programmable patterning of a minimum of 3 μL of nanoplasmonic bioink in 1 min and thus enables fabrication of a nanoplasmonic microarray immunosensor with 2 h simple incubation. The developed immunosensor was successfully applied for real-time, parallel detection of multiple cytokines (e.g., interleukin-6 (IL-6), tumor necrosis factor-alpha (TNF-α), and transforming growth factor-beta (TGF-β)) in immunomodulated macrophage samples. This integrated platform synergistically incorporates the concepts of nanosynthesis, nanofabrication, and nanobiosensing, showing great potential in the scalable production of label-free multiplex immunosensing devices with superior analytical performance for clinical applications in immunodiagnostics and immunotherapy.

Thermal Scanning-Probe Lithography for Broad-Band On-Demand Plasmonic Nanostructures on Transparent Substrates.

Thermal scanning-probe lithography (t-SPL) is a high-resolution nanolithography technique that enables the nanopatterning of thermosensitive materials by means of a heated silicon tip. It does not require alignment markers and gives the possibility to assess the morphology of the sample in a noninvasive way before, during, and after the patterning. In order to exploit t-SPL at its peak performances, the writing process requires applying an electric bias between the scanning hot tip and the sample, thereby restricting its application to conductive, optically opaque, substrates. In this work, we show a t-SPL-based method, enabling the noninvasive high-resolution nanolithography of photonic nanostructures onto optically transparent substrates across a broad-band visible and near-infrared spectral range. This was possible by intercalating an ultrathin transparent conductive oxide film between the dielectric substrate and the sacrificial patterning layer. This way, nanolithography performances comparable with those typically observed on conventional semiconductor substrates are achieved without significant changes of the optical response of the final sample. We validated this innovative nanolithography approach by engineering periodic arrays of plasmonic nanoantennas and showing the capability to tune their plasmonic response over a broad-band visible and near-infrared spectral range. The optical properties of the obtained systems make them promising candidates for the fabrication of hybrid plasmonic metasurfaces supported onto fragile low-dimensional materials, thus enabling a variety of applications in nanophotonics, sensing, and thermoplasmonics.

3D Printing‐Assisted Nanoimprint Lithography of Polymers

Fused filament fabrication, commonly referred to as 3D printing, is an additive manufacturing method finding plenty of applications nowadays. In contrast, polymer nanopatterning by nanolithographic techniques plays an important role in obtaining functional surfaces and coatings for applications in different fields including micro‐ and nanoelectronics. In spite of their relevance, additive manufacturing and polymer nanolithography have not found yet a common niche to be developed. Although both approaches are oriented to achieve different types of objects, it is shown that the confluence of both technologies can be desirable and potentially convenient. Herein, it is demonstrated that by employing conventional 3D printing, it is possible to fabricate nanostructured polymer surfaces in a relatively simple way by using similar approaches as those used in nanoimprint lithography but without the need for clean room conditions. To do that, a printed‐assisted nanoimprint lithography concept (3DPrANIL) has been tested for different types of polymer and silicon templates. It is demonstrated that a polymeric nanostructured hydrophilic template can be replicated accurately on another polymer rendering a nanostructured surface with enhanced hydrophobicity. The results support 3DPrANIL as novel method to obtain micro‐ and nanostructured surfaces with different functionalities like iridescence and hydrophobicity.

High-speed polarization-independent plasmonic modulator on a silicon waveguide.

The electrical bandwidth of an electro-optic modulator plays a vital role in determining the throughput of an optical communications link. We propose a broadband plasmonic electro-optic modulator operating at telecommunications wavelengths (λ0 ∼ 1550 nm), based on free carrier dispersion in indium tin oxide (ITO). The ITO is driven through its epsilon-near-zero point within the accumulation layers of metal-oxide-semiconductor (MOS) structures. The MOS structures are integrated into a pair of coupled metal-insulator-metal (MIM) waveguides aligned on a planarized silicon waveguide. The coupled MIM waveguides support symmetric and asymmetric plasmonic supermodes, excited adiabatically using mode transformation tapers, by the fundamental TM0 and TE0 modes of the underlying silicon waveguide, respectively, such that the modulator can operate in either mode as selected by the input polarisation to the silicon waveguide. The modulator has an active section 1.5 to 2 µm long, enabling the modulator to operate as a lumped element to bandwidths exceeding 200 GHz (3 dB electrical, RC-limited). The modulators produce an extinction ratio in the range of 3.5 to 6 dB, and an insertion loss in the range of 4 to 7.5 dB including input/output mode conversion losses. The AC drive voltage is ±1.75 V. The devices comprise only inorganic materials and are realisable using standard deposition, etching and nanolithography techniques.

Broadband and Spectrally Selective Photothermal Conversion through Nanocluster Assembly of Disordered Plasmonic Metasurfaces.

Plasmonic metasurfaces have been realized for efficient light absorption, thereby leading to photothermal conversion through nonradiative decay of plasmonic modes. However, current plasmonic metasurfaces suffer from inaccessible spectral ranges, costly and time-consuming nanolithographic top-down techniques for fabrication, and difficulty of scale-up. Here, we demonstrate a new type of disordered metasurface created by densely packing plasmonic nanoclusters of ultrasmall size on a planar optical cavity. The system either operates as a broadband absorber or offers a reconfigurable absorption band right across the visible region, resulting in continuous wavelength-tunable photothermal conversion. We further present a method to measure the temperature of plasmonic metasurfaces via surface-enhanced Raman spectroscopy (SERS), by incorporating single-walled carbon nanotubes (SWCNTs) as an SERS probe within the metasurfaces. Our disordered plasmonic system, generated by a bottom-up process, offers excellent performance and compatibility with efficient photothermal conversion. Moreover, it also provides a novel platform for various hot-electron and energy-harvesting functionalities.

Manipulating Nanopatterns on Two-Dimensional MoS2 Monolayers via Atomic Force Microscopy-Based Thermomechanical Nanolithography for Optoelectronic Device Fabrication

Atomically thin two-dimensional (2D) materials, such as monolayer molybdenum disulfide (MoS2), are candidate materials for future nanoelectronic and optoelectronic devices. However, implementation for some applications based on 2D materials strongly depends on fabricating functional nanostructures with specific shapes and sizes. This study reports a thermomechanical nanolithography technique for manipulating nanostructures on monolayer MoS2 using a heated atomic force microscope tip. Three types of nanopatterns, namely, the periodic spindle-shaped stick-slip structure, periodic triangular stick-slip structure, and nanogrooves, were fabricated on monolayer MoS2 using the great tensile stress produced via thermomechanical cleaving of the flexible poly(methyl methacrylate) (PMMA) layer underneath the MoS2 layer. Several feature sizes were studied to accurately control the fabricated nanostructures. A friction force step was observed when the tip scratched from PMMA to MoS2 in the same scribing process because of the low frictional characteristics of MoS2, indicating that MoS2 can reduce the friction as compared to the tip that directly scratches on PMMA. The direct nanocutting technique of 2D materials proposed herein is a promising tool for manipulating nanopatterns on 2D materials for the future nanoelectronic and optoelectronic devices.

Transparent and Reusable Nanostencil Lithography for Organic–Inorganic Hybrid Perovskite Nanodevices

AbstractOrganic—inorganic hybrid perovskites have attracted considerable attention for developing novel optoelectronic devices owing to their excellent photoresponses. However, conventional nanolithography of hybrid perovskites remains a challenge because they undergo severe damage in standard lithographic solvents, which prohibits device miniaturization and integration. In this study, a novel transparent stencil nanolithography (t‐SL) technique is developed based on focused ion beam (FIB)‐assisted polyethylene terephthalate (PET) direct patterning. The proposed t‐SL enables ultrahigh lithography resolution down to 100 nm and accurate stencil mask alignment. Moreover, the stencil mask can be reused more than ten times, which is cost‐effective for device fabrication. By applying this lithographic technique to hybrid perovskites, a high‐performance 2D hybrid perovskite heterostructure photodetector is fabricated. The responsivity and detectivity of the proposed heterostructure photodetector can reach up to 28.3 A W−1 and 1.5 × 1013 Jones, respectively. This t‐SL nanolithography technique based on FIB‐assisted PET direct patterning can effectively support the miniaturization and integration of hybrid‐perovskite‐based electronic devices.

Dynamic Metal-Phenolic Coordination Complexes for Versatile Surface Nanopatterning.

We report a general nanopatterning strategy that takes advantage of the dynamic coordination bonds between polyphenols and metal ions (e.g., Fe3+ and Cu2+) to create structures on surfaces with a range of properties. With this methodology, under acidic conditions, 29 metal-phenolic complex-based precursors composed of different polyphenols and metal ions are patterned using scanning probe and large-area cantilever free nanolithography techniques, resulting in a library of deposited metal-phenolic nanopatterns. Significantly, post-treatment of the patterns under basic conditions (i.e., ammonia vapor) triggers a change in coordination state and results in the in situ generation of more stable networks firmly attached to the underlying substrates. The methodology provides control over feature size, shape, and composition, almost regardless of substrate (e.g., Si, Au, and silicon nitride). Under reducing conditions (i.e., H2) at elevated temperatures (180-600 °C), the patterned features have been used as nanoreactors to synthesize individual metal nanoparticles. At room temperature, the ammonia-treated features can reduce Ag+ to form metal nanostructures and be modified with peptides, proteins, and thiolated DNA via Michael addition and/or Schiff base reaction. The generality of this technique should make it useful for a wide variety of researchers interested in modifying surfaces for catalytic, chemical and biological sensing, and template-directed assembly purposes.