A novel two-dimensional nanopattemed TiO2 thin film has been synthesized through the interaction between cationic Gemini surfactant molecules and the prepared TiO2 colloid nanoparticles with average diameters of 8 nm ...A novel two-dimensional nanopattemed TiO2 thin film has been synthesized through the interaction between cationic Gemini surfactant molecules and the prepared TiO2 colloid nanoparticles with average diameters of 8 nm by controlling the surface pressure of the monolayer. TEM photographs from the formed Gemini-TiO2 composite monolayer confirm that the prepared TiO2 film is of a branch nanopattern.展开更多
The development of nanoelectronics and nanotechnologies has been boosted significantly by the emergence of 2D materials because of their atomic thickness and peculiar properties,and developing a universal,precise patte...The development of nanoelectronics and nanotechnologies has been boosted significantly by the emergence of 2D materials because of their atomic thickness and peculiar properties,and developing a universal,precise patterning technology for single-layer 2D materials is critical for assembling nanodevices.Demonstrated here is a nanomachining technique using electrical breakdown by an AFM tip to fabricate nanopores,nanostrips,and other nanostructures on demand.This can be achieved by voltage scanning or applying a constant voltage while moving the tip.By measuring the electrical current,the formation process on single-layer materials was shown quantitatively.The present results provide evidence of successful pattern fabrication on single-layer MoS2,boron nitride,and graphene,although further confirmation is still needed.The proposed method holds promise as a general nanomachining technology for the future.展开更多
Nanoparticles monolayer formation by spin coating is considered to be a simple, fast and inexpensive nanopatteming technique However, the parameters that govern the overall growth process in this technique are not com...Nanoparticles monolayer formation by spin coating is considered to be a simple, fast and inexpensive nanopatteming technique However, the parameters that govern the overall growth process in this technique are not completely quantified and techniques for the controlled and continuous growth of close packed monolayer particle arrays without defects need to be developed. In this paper, an ordered particle array formation process is analyzed theoretically, employing material flux balance and parti- cle-subjected forces balance, based on the film thickness model of spin coating and evaporation rate law. A series of experi- ments were conducted using silica particle suspensions with various particle volume fractions and different spin speeds. The results show that the spin speed should match the particle volume fraction to meet the requirements of material flux and particles movement in order to obtain a close packed monolayer film. The formation mechanism of fabrication defects involving particle agglomeration and uncontrollable voids were analyzed qualitatively based on crystal growth theory, and validation experiments were performed. The formation of highly uniform close-packed monolayer films was demonstrated and the condi- tion requirements for achieving monolayer nanoparticles array with good quality presented.展开更多
Three-dimensional(3D)nanoarchitectures have offered unprecedented material performances in diverse applications like energy storages,catalysts,electronic,mechanical,and photonic devices.These outstanding performances ...Three-dimensional(3D)nanoarchitectures have offered unprecedented material performances in diverse applications like energy storages,catalysts,electronic,mechanical,and photonic devices.These outstanding performances are attributed to unusual material properties at the nanoscale,enormous surface areas,a geometrical uniqueness,and comparable feature sizes with optical wavelengths.For the practical use of the unusual nanoscale properties,there have been developments for macroscale fabrications of the 3D nanoarchitectures with process areas over centimeter scales.Among the many fabrication methods for 3D structures at the nanoscale,proximity-field nanopatterning(PnP)is one of the promising techniques that generates 3D optical holographic images and transforms them into material structures through a lithographic process.Using conformal and transparent phase masks as a key factor,the PnP process has advantages in terms of stability,uniformity,and reproducibility for 3D nanostructures with periods from 300 nm to several micrometers.Other merits of realizing precise 3D features with sub-100 nm and rapid processes are attributed to the interference of coherent light diffracted by phase masks.In this review,to report the overall progress of PnP from 2003,we present a comprehensive understanding of PnP,including its brief history,the fundamental principles,symmetry control of 3D nanoarchitectures,material issues for the phase masks,and the process area expansion to the wafer-scale for the target applications.Finally,technical challenges and prospects are discussed for further development and practical applications of the PnP technique.展开更多
Functionalization of silicon substrate surfaces with a stable monolayer for resisting non-specific adsorption of proteins has attracted great interest,since it is directly relevant to the development of miniature,sili...Functionalization of silicon substrate surfaces with a stable monolayer for resisting non-specific adsorption of proteins has attracted great interest,since it is directly relevant to the development of miniature,silicon-based biosensors and implantable microdevices,such as silicon-neuron interfaces.This brief review summarizes our contribution to the development of robust monolayers grown by surface hydrosilylation on atomically flat,hydrogen-terminated silicon surfaces.The review also outlines our strategy and progress on the fabrication of single molecule patterns on such monolayer platforms.展开更多
Nanopattem transformation behaviors of polyisoprene-block-polystyrene-block-poly（2-vinylpyridine） （PI-b-PS-b-P2VP） asymmetric ABC triblock copolymer were investigated systematically with various control para- mete...Nanopattem transformation behaviors of polyisoprene-block-polystyrene-block-poly（2-vinylpyridine） （PI-b-PS-b-P2VP） asymmetric ABC triblock copolymer were investigated systematically with various control para- meters, including different solvents for polymer solution and annealing conditions in this paper. Ordered nanopattern of PI-b-PS-b-P2VP with hexagonal cylinders could be obtained when PI-b-PS-b-P2VP toluene solution was spin-coated on silicon substrate followed by toluene vapor annealing process. When the film with hexagonal and cylindrical nanopattern was exposed to saturated toluene vapor, the order-order transition of cylindrical nanopattern to parallel nanopattern was observed due to the strong selectivity of toluene to PS and PI blocks. Furthermore, fingerprint nanopattern could also be obtained by solvent annealing in tetrahydrofuran vapor. The nanopattern trans- formation was due to different selectivity of solvents and incompatibilities of the three blocks of PI-b-PS-b-P2VP under various solvent annealing conditions.展开更多
We present measurements of the in situ, microscopic architecture of a self- assembled bilayer at the interface between a regularly nanopatterned surface and an aqueous sub-phase using neutron reflectometry. The substr...We present measurements of the in situ, microscopic architecture of a self- assembled bilayer at the interface between a regularly nanopatterned surface and an aqueous sub-phase using neutron reflectometry. The substrate is patterned with a rectangular array of nanoscale holes. Because of the high quality of the pattern, using neutron reflectometry, we are able to map the surface-normal density distribution of the patterned silicon, the penetration of water into the pattern, and the distribution of a deposited film inside and outside of the etched holes. In this stud; 1,2-dilauroyl-sn-glycero-3-phosphocholine （DLPC） single bilayers were deposited on the hydrophilic patterned surface. For bilayers deposited either by vesicle fusion （VF） or by the Langmuir-Schaefer （L-S） technique, the most consistent model found to fit the data shows that the lipids form bilayer coatings on top of the substrate as well as the bottoms of the holes in an essentially conformal fashion. However, while there is a single bilayer on the unetched silicon surface, the lipids coating the bottoms of the holes form a complex bimodal structure consistent with a rough surface produced by the etching process. This study provides insight into film transfer both outside and inside regular nanopatterned features.展开更多
The morphology of linear polybutadiene physisorbed on freshly cleaved mica from a dilute polymer solution is investigated through atomic force microscopy.A fine-structure study shows that the monolayer morphology in a...The morphology of linear polybutadiene physisorbed on freshly cleaved mica from a dilute polymer solution is investigated through atomic force microscopy.A fine-structure study shows that the monolayer morphology in air(after rapid solvent evaporation)depends strongly on the molecular weight(Mw)of the linear polymer,the adsorbed amount,and the conformation adopted by the adsorbed polymer chains under good solvent conditions.The dependence of the observed polymer structure on Mw is most significant for samples with high surface density,where the intermolecular interactions among the adsorbed polymers are important.For high surface density,the adsorbed polymers tend to aggregate and minimize unfavorable contacts with air for all of the different Mw samples,leading to an isotropic structural pattern.These structural phenomena with increasing surface density are explained on the basis of the intermolecular interactions of the adsorbed polymers under good solvent conditions,and after the abrupt solvent evaporation corresponding to poor solvent conditions.The experimental observations are further discussed using the results obtained from molecular dynamics simulations of a simple coarse-grained model.展开更多
Anisotropic nanopatterns have potentials in constructing novel plasmonic structures which have various applications in such as super-resolution microscopy, medicine, and sensors. However, it remains challenging to bui...Anisotropic nanopatterns have potentials in constructing novel plasmonic structures which have various applications in such as super-resolution microscopy, medicine, and sensors. However, it remains challenging to build big anisotropic nanopatterns that are suitable for big noble metal nanoparticles. Herein, we report a simple and reliable strategy for constructing DNA origami-based big anisotropic nanopatterns with controlled size and shape, nanoscale resolution, and fully addressability. Two kinds of basic DNA origami nanoblocks-cross-shaped and rectangular DNA origami units were used. We have demonstrated that by encoding nanoblocks' edges, anisotropic higher-order nanopatterns, such as dimer, trimer, tetramer and mini "windmill" like pentamer nanopatterns could be constructed. To show the potential use as template to direct the assembly of anisotropic nanoparticles arrays, a proof of concept work was conducted by anchoring streptavidin nanoparticles on the "windmill" template to form a chiral array. Significantly, these nanopatterns have the sizes of hundreds of nanometers, which are in principle also suitable for big noble metal nanoparticles arrays.展开更多
A method is presented for nano-patterning a diffraction grating on human hair with a focused ion beam. Strands of brown hair are patterned with hyperbolas and Archimedean spirals whose pitches range from 540 nm to 104...A method is presented for nano-patterning a diffraction grating on human hair with a focused ion beam. Strands of brown hair are patterned with hyperbolas and Archimedean spirals whose pitches range from 540 nm to 1040 nm. Exposure of the hair strands to white light at various incident angles demonstrates that light of varying wavelengths is diffracted by the diffraction gratings. The diffraction causes the brown strands of hair to reflect light from the entire range of visible light.展开更多
Nanofabrication of two-dimensional materials through mechanical machining is normally influenced by not only process parameters such as load and velocity but also intrinsic properties such as strength and thickness.He...Nanofabrication of two-dimensional materials through mechanical machining is normally influenced by not only process parameters such as load and velocity but also intrinsic properties such as strength and thickness.Herein,we examined the effects of graphene oxide(GO)film thickness on nanofabrication on the plane surfaces and at the step edges using scanning probe microscope lithography.The material removal of GO initiates at the load above a critical value,which strongly depends on film thickness and locations.With the increase in film thickness,the critical load decreases monotonically on the plane surfaces but increases gradually at the step edges.Further,the critical load for the GO monolayer at the step edges is at least 25 times lower than that on the plane surfaces,and the gap decreases to around 3 times when GO thickness increases to four layers.Then,mechanical nanofabrication initiating from the GO step edge allows producing various nanopatterns under extremely low loads around 1 nN.Finally,the GO nanostructures are deoxidized by annealing at 800°C in high-purity argon to restore their highly functionalized conjugated structures,which are supported by X-ray diffraction and Raman characterizations.This work provides a novel approach to fabricating graphene-like nanostructures by deoxidizing GO after nanofabrication,which holds significant potential for applications in graphene-based devices.展开更多
This paper presents a novel technique to fabricate metallic nanowires in selective areas on a Si substrate.Thermoplastic drawing of viscous metallic glass from cavities etched in Si can produce metallic nanowires.The ...This paper presents a novel technique to fabricate metallic nanowires in selective areas on a Si substrate.Thermoplastic drawing of viscous metallic glass from cavities etched in Si can produce metallic nanowires.The length and diameter of nanowires can be controlled by adjusting the drawing conditions without changing the Si mold.A thin metal shadow mask is stacked above the Si mold during thermoplastic drawing to fabricate the nanowires only in specific locations.The mask restricts the flow of metallic glass to predefined shapes on the mask,resulting in the formation of nanowires in selected areas on Si.An Al foil-based mask made by a benchtop vinyl cutter is used to demonstrate the proof-of-concept.Even a simple Al foil mask enables the positioning of metallic nanowires in selective areas as small as 200μm on Si.The precision of the vinyl cutter limits the smallest dimensions of the patterned areas,which can be further improved by using laser-fabricated stencil masks.Results show that a single row of metallic glass nanowires can be patterned on Si using selective thermoplastic drawing.Controllable positioning of metallic nanowires on substrates can enable new applications and characterization techniques for nanostructures.展开更多
In this paper, microphase behavior of an ABC triblock copolymer, polystyrene-block-poly（2-vinylpyridine）-block- poly（ethylene oxide）, namely PS-b-P2VP-b-PEO, was systematically studied during spin-coating and solv...In this paper, microphase behavior of an ABC triblock copolymer, polystyrene-block-poly（2-vinylpyridine）-block- poly（ethylene oxide）, namely PS-b-P2VP-b-PEO, was systematically studied during spin-coating and solvent vapor annealing based on various parameters, including the types of the solvent, spin speed and thickness. The morphological features and the microdomain location of the different blocks were characterized by atomic force microscope （AFM） and high resolution transmission electron microscopy （HRTEM）. With increasing thickness, the order-order transition from nanopores array to the pattern of nanostripes was observed due to microdomain coarsening. These processes of pattern transformation were based on the selectivity of toluene for different blocks and on the contact time between solvent molecules and the three blocks. This work provides different templates for preparation of gold nanoparticle array on silicon wafer, which can be adopted as an active surface-enhanced Raman scattering （SERS） substrate for poly（3-hexylthiophene） （P3HT）.展开更多
Non-planar morphology is a common feature of devices applied in various physical fields,such as light or fluid,which pose a great challenge for surface nano-patterning to improve their performance.The present study pr...Non-planar morphology is a common feature of devices applied in various physical fields,such as light or fluid,which pose a great challenge for surface nano-patterning to improve their performance.The present study proposes a discretely-supported nanoimprint.lithography(NIL)technique to fabricate nanostructures on the extremely non-planar surface,namely high-spatial-frequency stepped surface.The designed discretely imprinting template implanted a discretely-supported intermediate buffer layer made of sparse pillars arrays.This allowed the simultaneous generation of air-cushion-like buffer and reliable support to the thin structured layer in the template.The resulting low bending stiffness and distributed concentrated load of the template jointly overcome the contact difficulty with a stepped surface,and enable the template to encase the stepped protrusion as tight as possible.Based on the proposed discretely-supported NIL,nanostructures were fabricated on the luminous interface of light emitting diodes chips that covered with micrometer step electrodes pad.About 96%of the utilized indium tin oxide transparent current spreading layer surface on top of the light emitting diode(LED)chips was coated with nanoholes array,with an increase by more than 40%in the optical output power.The excellent ability of nanopatterning a non-planar substrate could potentially lead innovate design and development of high performance device based on discretely-supported NIL.展开更多
基金supported by the National Natural Science Foundation of China(No.20473057)Shanghai Nanotechnology Promotion Center(No.0352nm094,No.0452nm088).
文摘A novel two-dimensional nanopattemed TiO2 thin film has been synthesized through the interaction between cationic Gemini surfactant molecules and the prepared TiO2 colloid nanoparticles with average diameters of 8 nm by controlling the surface pressure of the monolayer. TEM photographs from the formed Gemini-TiO2 composite monolayer confirm that the prepared TiO2 film is of a branch nanopattern.
基金supported by the National Natural Science Foundation of China(Grant Nos.12075191,12388101,and 12241201)the Fundamental Research Funds for the Central Universities(Grant No.D5000230120)the Natural Science Basic Research Program of Shaanxi Province(Grant No.2023-JC-YB-541).
文摘The development of nanoelectronics and nanotechnologies has been boosted significantly by the emergence of 2D materials because of their atomic thickness and peculiar properties,and developing a universal,precise patterning technology for single-layer 2D materials is critical for assembling nanodevices.Demonstrated here is a nanomachining technique using electrical breakdown by an AFM tip to fabricate nanopores,nanostrips,and other nanostructures on demand.This can be achieved by voltage scanning or applying a constant voltage while moving the tip.By measuring the electrical current,the formation process on single-layer materials was shown quantitatively.The present results provide evidence of successful pattern fabrication on single-layer MoS2,boron nitride,and graphene,although further confirmation is still needed.The proposed method holds promise as a general nanomachining technology for the future.
基金supported by the National Natural Science Foundation of China(Grant Nos.51375381,51575427 and 51675422)the 2015 Overall Planning Innovation Project Foundation of Shaanxi Province(Grant No.2015KTCQ01-36)
文摘Nanoparticles monolayer formation by spin coating is considered to be a simple, fast and inexpensive nanopatteming technique However, the parameters that govern the overall growth process in this technique are not completely quantified and techniques for the controlled and continuous growth of close packed monolayer particle arrays without defects need to be developed. In this paper, an ordered particle array formation process is analyzed theoretically, employing material flux balance and parti- cle-subjected forces balance, based on the film thickness model of spin coating and evaporation rate law. A series of experi- ments were conducted using silica particle suspensions with various particle volume fractions and different spin speeds. The results show that the spin speed should match the particle volume fraction to meet the requirements of material flux and particles movement in order to obtain a close packed monolayer film. The formation mechanism of fabrication defects involving particle agglomeration and uncontrollable voids were analyzed qualitatively based on crystal growth theory, and validation experiments were performed. The formation of highly uniform close-packed monolayer films was demonstrated and the condi- tion requirements for achieving monolayer nanoparticles array with good quality presented.
基金supported by Creative Materials Discovery Program through the National Research Foundation of Korea(NRF)funded by Ministry of Science and ICT(No.2020M3D1A1110522).
文摘Three-dimensional(3D)nanoarchitectures have offered unprecedented material performances in diverse applications like energy storages,catalysts,electronic,mechanical,and photonic devices.These outstanding performances are attributed to unusual material properties at the nanoscale,enormous surface areas,a geometrical uniqueness,and comparable feature sizes with optical wavelengths.For the practical use of the unusual nanoscale properties,there have been developments for macroscale fabrications of the 3D nanoarchitectures with process areas over centimeter scales.Among the many fabrication methods for 3D structures at the nanoscale,proximity-field nanopatterning(PnP)is one of the promising techniques that generates 3D optical holographic images and transforms them into material structures through a lithographic process.Using conformal and transparent phase masks as a key factor,the PnP process has advantages in terms of stability,uniformity,and reproducibility for 3D nanostructures with periods from 300 nm to several micrometers.Other merits of realizing precise 3D features with sub-100 nm and rapid processes are attributed to the interference of coherent light diffracted by phase masks.In this review,to report the overall progress of PnP from 2003,we present a comprehensive understanding of PnP,including its brief history,the fundamental principles,symmetry control of 3D nanoarchitectures,material issues for the phase masks,and the process area expansion to the wafer-scale for the target applications.Finally,technical challenges and prospects are discussed for further development and practical applications of the PnP technique.
基金supported by the Welch Foundation grant E-1498NSF CAREER Award (CTS-0349228 to CC)+1 种基金grant DMR-0706627NIH R21 HD058985
文摘Functionalization of silicon substrate surfaces with a stable monolayer for resisting non-specific adsorption of proteins has attracted great interest,since it is directly relevant to the development of miniature,silicon-based biosensors and implantable microdevices,such as silicon-neuron interfaces.This brief review summarizes our contribution to the development of robust monolayers grown by surface hydrosilylation on atomically flat,hydrogen-terminated silicon surfaces.The review also outlines our strategy and progress on the fabrication of single molecule patterns on such monolayer platforms.
基金Supported by the National Natural Science Foundations of China（Nos.51273048, 51203025） and the Natural Science Foundation of Guangdong Province, China（No.S2012040007725）.
文摘Nanopattem transformation behaviors of polyisoprene-block-polystyrene-block-poly（2-vinylpyridine） （PI-b-PS-b-P2VP） asymmetric ABC triblock copolymer were investigated systematically with various control para- meters, including different solvents for polymer solution and annealing conditions in this paper. Ordered nanopattern of PI-b-PS-b-P2VP with hexagonal cylinders could be obtained when PI-b-PS-b-P2VP toluene solution was spin-coated on silicon substrate followed by toluene vapor annealing process. When the film with hexagonal and cylindrical nanopattern was exposed to saturated toluene vapor, the order-order transition of cylindrical nanopattern to parallel nanopattern was observed due to the strong selectivity of toluene to PS and PI blocks. Furthermore, fingerprint nanopattern could also be obtained by solvent annealing in tetrahydrofuran vapor. The nanopattern trans- formation was due to different selectivity of solvents and incompatibilities of the three blocks of PI-b-PS-b-P2VP under various solvent annealing conditions.
文摘We present measurements of the in situ, microscopic architecture of a self- assembled bilayer at the interface between a regularly nanopatterned surface and an aqueous sub-phase using neutron reflectometry. The substrate is patterned with a rectangular array of nanoscale holes. Because of the high quality of the pattern, using neutron reflectometry, we are able to map the surface-normal density distribution of the patterned silicon, the penetration of water into the pattern, and the distribution of a deposited film inside and outside of the etched holes. In this stud; 1,2-dilauroyl-sn-glycero-3-phosphocholine （DLPC） single bilayers were deposited on the hydrophilic patterned surface. For bilayers deposited either by vesicle fusion （VF） or by the Langmuir-Schaefer （L-S） technique, the most consistent model found to fit the data shows that the lipids form bilayer coatings on top of the substrate as well as the bottoms of the holes in an essentially conformal fashion. However, while there is a single bilayer on the unetched silicon surface, the lipids coating the bottoms of the holes form a complex bimodal structure consistent with a rough surface produced by the etching process. This study provides insight into film transfer both outside and inside regular nanopatterned features.
基金the EPSRCDTA and the Institute of Materials and Processes,School of Engineering at the University of Edinburgh.
文摘The morphology of linear polybutadiene physisorbed on freshly cleaved mica from a dilute polymer solution is investigated through atomic force microscopy.A fine-structure study shows that the monolayer morphology in air(after rapid solvent evaporation)depends strongly on the molecular weight(Mw)of the linear polymer,the adsorbed amount,and the conformation adopted by the adsorbed polymer chains under good solvent conditions.The dependence of the observed polymer structure on Mw is most significant for samples with high surface density,where the intermolecular interactions among the adsorbed polymers are important.For high surface density,the adsorbed polymers tend to aggregate and minimize unfavorable contacts with air for all of the different Mw samples,leading to an isotropic structural pattern.These structural phenomena with increasing surface density are explained on the basis of the intermolecular interactions of the adsorbed polymers under good solvent conditions,and after the abrupt solvent evaporation corresponding to poor solvent conditions.The experimental observations are further discussed using the results obtained from molecular dynamics simulations of a simple coarse-grained model.
基金supported by the National Basic Research Program of China (2012CB932600)the National Natural Science Foundation of China(20725516, 90913014, 21028005 and 21103219)Shanghai Pujiang Program (11PJ1412000)
文摘Anisotropic nanopatterns have potentials in constructing novel plasmonic structures which have various applications in such as super-resolution microscopy, medicine, and sensors. However, it remains challenging to build big anisotropic nanopatterns that are suitable for big noble metal nanoparticles. Herein, we report a simple and reliable strategy for constructing DNA origami-based big anisotropic nanopatterns with controlled size and shape, nanoscale resolution, and fully addressability. Two kinds of basic DNA origami nanoblocks-cross-shaped and rectangular DNA origami units were used. We have demonstrated that by encoding nanoblocks' edges, anisotropic higher-order nanopatterns, such as dimer, trimer, tetramer and mini "windmill" like pentamer nanopatterns could be constructed. To show the potential use as template to direct the assembly of anisotropic nanoparticles arrays, a proof of concept work was conducted by anchoring streptavidin nanoparticles on the "windmill" template to form a chiral array. Significantly, these nanopatterns have the sizes of hundreds of nanometers, which are in principle also suitable for big noble metal nanoparticles arrays.
文摘A method is presented for nano-patterning a diffraction grating on human hair with a focused ion beam. Strands of brown hair are patterned with hyperbolas and Archimedean spirals whose pitches range from 540 nm to 1040 nm. Exposure of the hair strands to white light at various incident angles demonstrates that light of varying wavelengths is diffracted by the diffraction gratings. The diffraction causes the brown strands of hair to reflect light from the entire range of visible light.
基金supported by the National Natural Science Foundation of China(Nos.52350411,52122507 and 52235004)Sichuan Science and Technology Program(2023NSFSC1988 and 2023YFSY0004)the Fundamental Research Funds for the Central University(No.2682021ZTPY095).
文摘Nanofabrication of two-dimensional materials through mechanical machining is normally influenced by not only process parameters such as load and velocity but also intrinsic properties such as strength and thickness.Herein,we examined the effects of graphene oxide(GO)film thickness on nanofabrication on the plane surfaces and at the step edges using scanning probe microscope lithography.The material removal of GO initiates at the load above a critical value,which strongly depends on film thickness and locations.With the increase in film thickness,the critical load decreases monotonically on the plane surfaces but increases gradually at the step edges.Further,the critical load for the GO monolayer at the step edges is at least 25 times lower than that on the plane surfaces,and the gap decreases to around 3 times when GO thickness increases to four layers.Then,mechanical nanofabrication initiating from the GO step edge allows producing various nanopatterns under extremely low loads around 1 nN.Finally,the GO nanostructures are deoxidized by annealing at 800°C in high-purity argon to restore their highly functionalized conjugated structures,which are supported by X-ray diffraction and Raman characterizations.This work provides a novel approach to fabricating graphene-like nanostructures by deoxidizing GO after nanofabrication,which holds significant potential for applications in graphene-based devices.
基金The authors would like to thank the financial support from National Science Foundation(NSF)through CMMI CAREER Award#1921435.
文摘This paper presents a novel technique to fabricate metallic nanowires in selective areas on a Si substrate.Thermoplastic drawing of viscous metallic glass from cavities etched in Si can produce metallic nanowires.The length and diameter of nanowires can be controlled by adjusting the drawing conditions without changing the Si mold.A thin metal shadow mask is stacked above the Si mold during thermoplastic drawing to fabricate the nanowires only in specific locations.The mask restricts the flow of metallic glass to predefined shapes on the mask,resulting in the formation of nanowires in selected areas on Si.An Al foil-based mask made by a benchtop vinyl cutter is used to demonstrate the proof-of-concept.Even a simple Al foil mask enables the positioning of metallic nanowires in selective areas as small as 200μm on Si.The precision of the vinyl cutter limits the smallest dimensions of the patterned areas,which can be further improved by using laser-fabricated stencil masks.Results show that a single row of metallic glass nanowires can be patterned on Si using selective thermoplastic drawing.Controllable positioning of metallic nanowires on substrates can enable new applications and characterization techniques for nanostructures.
基金supported by the National Natural Science Foundation of China(Nos.51273048 and 51203025)Natural Science Foundation of Guangdong Province(No.S2012040007725)
文摘In this paper, microphase behavior of an ABC triblock copolymer, polystyrene-block-poly（2-vinylpyridine）-block- poly（ethylene oxide）, namely PS-b-P2VP-b-PEO, was systematically studied during spin-coating and solvent vapor annealing based on various parameters, including the types of the solvent, spin speed and thickness. The morphological features and the microdomain location of the different blocks were characterized by atomic force microscope （AFM） and high resolution transmission electron microscopy （HRTEM）. With increasing thickness, the order-order transition from nanopores array to the pattern of nanostripes was observed due to microdomain coarsening. These processes of pattern transformation were based on the selectivity of toluene for different blocks and on the contact time between solvent molecules and the three blocks. This work provides different templates for preparation of gold nanoparticle array on silicon wafer, which can be adopted as an active surface-enhanced Raman scattering （SERS） substrate for poly（3-hexylthiophene） （P3HT）.
基金financed by the National Key R&D Program of China(No.2017YFB1102900)the Natural Science Foundation of China(No.51805422)+1 种基金the China Postdoctoral Science Foundation(No.2019M653592)the Basic Research Program of Natural Science of Shaanxi Province of China(No.2019JLM-5).
文摘Non-planar morphology is a common feature of devices applied in various physical fields,such as light or fluid,which pose a great challenge for surface nano-patterning to improve their performance.The present study proposes a discretely-supported nanoimprint.lithography(NIL)technique to fabricate nanostructures on the extremely non-planar surface,namely high-spatial-frequency stepped surface.The designed discretely imprinting template implanted a discretely-supported intermediate buffer layer made of sparse pillars arrays.This allowed the simultaneous generation of air-cushion-like buffer and reliable support to the thin structured layer in the template.The resulting low bending stiffness and distributed concentrated load of the template jointly overcome the contact difficulty with a stepped surface,and enable the template to encase the stepped protrusion as tight as possible.Based on the proposed discretely-supported NIL,nanostructures were fabricated on the luminous interface of light emitting diodes chips that covered with micrometer step electrodes pad.About 96%of the utilized indium tin oxide transparent current spreading layer surface on top of the light emitting diode(LED)chips was coated with nanoholes array,with an increase by more than 40%in the optical output power.The excellent ability of nanopatterning a non-planar substrate could potentially lead innovate design and development of high performance device based on discretely-supported NIL.
