Solid-state nanopores with controllable pore size and morphology have huge application potential.However,it has been very challenging to process sub-10 nm silicon nanopore arrays with high efficiency and high quality ...Solid-state nanopores with controllable pore size and morphology have huge application potential.However,it has been very challenging to process sub-10 nm silicon nanopore arrays with high efficiency and high quality at low cost.In this study,a method combining metal-assisted chemical etching and machine learning is proposed to fabricate sub-10 nm nanopore arrays on silicon wafers with various dopant types and concentrations.Through a SVM algorithm,the relationship between the nanopore structures and the fabrication conditions,including the etching solution,etching time,dopant type,and concentration,was modeled and experimentally verified.Based on this,a processing parameter window for generating regular nanopore arrays on silicon wafers with variable doping types and concentrations was obtained.The proposed machine-learning-assisted etching method will provide a feasible and economical way to process high-quality silicon nanopores,nanostructures,and devices.展开更多
Porous silicon （PSi） prepared from Pt metal-assisted chemical etching （MACE） was demonstrated to possess higher hydrosi- lylation efficiency （-57%） than anodized PSi （-11%） by surface reaction with co-undeceny...Porous silicon （PSi） prepared from Pt metal-assisted chemical etching （MACE） was demonstrated to possess higher hydrosi- lylation efficiency （-57%） than anodized PSi （-11%） by surface reaction with co-undecenyl alcohol （UO）. Deconvolution of the SiHx （x = 1-3） stretching bands revealed the abundance of SiH2 species on MaCE PSi was 53%, -10% higher than on ano- dized samples, while both of Sill1 and Sill3 were -5% lower correspondently on MaCE PSi than on anodized samples. The surface SiHx abundances were suggested to account for the higher hydrosilylation efficiency on MaCE PSi. Optimization of Pt-assisted chemical etching parameters suggested a 7-15 nm thick Pt-coating and an etching time of 3-10 min for biochip ap- plications. Scanning electron microscopy images revealed that an isotropic top meso-porous layer was beneficial for hydrosi- lylation and long-term durability under ambient conditions. To end, an example of histidine-tagged protein immobilization and microarray was illustrated. Combining the materials＇ property, surface chemistry, and micro-fabrication technology together, we envision that silicon based biochip applications have a prosperous future.展开更多
CoFe_2O_4 ferrite nanowire arrays are fabricated in porous silicon templates. The porous silicon templates are prepared via metal-assisted chemical etching with gold（Au） nanoparticles as the catalyst. Subsequently, ...CoFe_2O_4 ferrite nanowire arrays are fabricated in porous silicon templates. The porous silicon templates are prepared via metal-assisted chemical etching with gold（Au） nanoparticles as the catalyst. Subsequently, CoFe_2O_4 ferrite nanowires are successfully synthesized into porous silicon templates by the sol–gel method. The magnetic hysteresis loop of nanowire array shows an isotropic feature of magnetic properties. The coercivity and squareness ratio（M_r/M_s） of ensemble nanowires are found to be 630 Oe（1 Oe = 79.5775 A·m^（-1） and 0.4 respectively. However, the first-order reversal curve（FORC） is adopted to reveal the probability density function of local magnetostatic properties（i.e., interwire interaction field and coercivity）. The FORC diagram shows an obvious distribution feature for interaction field and coercivity. The local coercivity with a value of about 1000 Oe is found to have the highest probability.展开更多
Highly ordered silicon nanorod（Si NR） arrays with controllable geometry are fabricated via nanosphere lithography and metal-assisted chemical etching. It is demonstrated that the key to achieving a high-quality meta...Highly ordered silicon nanorod（Si NR） arrays with controllable geometry are fabricated via nanosphere lithography and metal-assisted chemical etching. It is demonstrated that the key to achieving a high-quality metal mask is to construct a non-close-packed template that can be removed with negligible damage to the mask. Hydrophobicity of Si NR arrays of different geometries is also studied. It is shown that the nanorod structures are effectively quasi-hydrophobic with a contact angle as high as 142°, which would be useful in self-cleaning nanorod-based device applications.展开更多
Nanostructures of silicon are gradually becoming hot candidate due to outstanding capability for trapping light and improving conversion efficiency of solar cell. In this paper, silicon nanowires（SiNWs） and silicon ...Nanostructures of silicon are gradually becoming hot candidate due to outstanding capability for trapping light and improving conversion efficiency of solar cell. In this paper, silicon nanowires（SiNWs） and silicon inverted pyramid arrays（SiIPs） were introduced on surface of Gr-Si solar cell through silver and copper-catalyzed chemical etching, respectively. The effects of SiNWs and SiIPs on carrier lifetime, optical properties and efficiency of Gr-SiNWs and Gr-SiIPs solar cells were systematically analyzed. The results show that the inverted pyramid arrays have more excellent ability for balancing antireflectance loss and surface area enlargement. The power conversion efficiency（PCE） and carrier lifetime of Gr-SiIPs devices respectively increase by 62% and 34% by comparing with that of Gr-SiNWs solar cells. Finally, the Gr-SiIPs cell with PCE of 5.63% was successfully achieved through nitric acid doping. This work proposes a new strategy to introduce the inverted pyramid arrays for improving the performance of Gr-Si solar cells.展开更多
On-demand hydrogen generation is desired for fuel cells,energy storage,and clean energy applications.Silicon nanowires(SiNWs)and nanoparticles(SiNPs)have been reported to generate hydrogen by reacting with water,but t...On-demand hydrogen generation is desired for fuel cells,energy storage,and clean energy applications.Silicon nanowires(SiNWs)and nanoparticles(SiNPs)have been reported to generate hydrogen by reacting with water,but these processes usually require external assistance,such as light,electricity or catalysts.Herein,we demonstrate that a porous SiNWs array,which is fabricated via the metal-assisted anodic etching(MAAE)method,reacts with water under ambient and dark conditions without any energy inputs.The reaction between the SiNWs and water generates hydrogen at a rate that is about ten times faster than the reported rates of other Si nanostructures.Two possible sources of enhancement are discussed:SiNWs maintain their high specific surface area as they don’t agglomerate,and the intrinsic strain of the nanowires promotes the reactivity.Moreover,the porous SiNWs array is portable,reusable,and environmentally friendly,yielding a promising route to produce hydrogen in a distributed manner.展开更多
In this study, we report that height-controlled vertically etched silicon nano- column arrays （vSNAs） induce strong growth cone-to-substrate coupling and accelerate in vitro neurite development while preserving the ...In this study, we report that height-controlled vertically etched silicon nano- column arrays （vSNAs） induce strong growth cone-to-substrate coupling and accelerate in vitro neurite development while preserving the essential features of initial neurite formation. Large-scale preparation of vSNAs with flat head morphology enabled the generation of well-controlled topographical stimulation without cellular impalement. A systematic analysis on topography- induced variations on cellular morphology and cytoskeletal dynamics was conducted. In addition, neurite development on the grid-patterned vSNAs exhibited preferential adhesion to the nanostructured region and outgrowth directionality. The arrangement of cytoskeletal proteins and the expression of a focal adhesion complex indicated that a strong coupling existed between the underlying nanocolumns and growth cones. Furthermore, the height-controlled nanocolumn substrates differentially modulated neurite polarization and elongation. Our findings provide an important insight into neuron-nanotopography interactions and their role in cell adhesion and neurite development.展开更多
基金supported by the National Natural Science Foundation of China[Grant Nos.51975127,U20A6004]the Guangdong-Hong Kong Technology Coopeartion[Grant No.GHP/112/19GD]from Hong Kong Innovation and Technology Commission+1 种基金Research and Development Program of Guangdong Province[Grant No.2020A0505140008]the Fund of Key-Area Research and Development Program of Guangdong Province[Grant No.2018B090906002]。
文摘Solid-state nanopores with controllable pore size and morphology have huge application potential.However,it has been very challenging to process sub-10 nm silicon nanopore arrays with high efficiency and high quality at low cost.In this study,a method combining metal-assisted chemical etching and machine learning is proposed to fabricate sub-10 nm nanopore arrays on silicon wafers with various dopant types and concentrations.Through a SVM algorithm,the relationship between the nanopore structures and the fabrication conditions,including the etching solution,etching time,dopant type,and concentration,was modeled and experimentally verified.Based on this,a processing parameter window for generating regular nanopore arrays on silicon wafers with variable doping types and concentrations was obtained.The proposed machine-learning-assisted etching method will provide a feasible and economical way to process high-quality silicon nanopores,nanostructures,and devices.
基金the financial support of the National Basic Research Program of China(2013CB922101)the National Natural Science Foundation of China(20827001,91027019,21021062)
文摘Porous silicon （PSi） prepared from Pt metal-assisted chemical etching （MACE） was demonstrated to possess higher hydrosi- lylation efficiency （-57%） than anodized PSi （-11%） by surface reaction with co-undecenyl alcohol （UO）. Deconvolution of the SiHx （x = 1-3） stretching bands revealed the abundance of SiH2 species on MaCE PSi was 53%, -10% higher than on ano- dized samples, while both of Sill1 and Sill3 were -5% lower correspondently on MaCE PSi than on anodized samples. The surface SiHx abundances were suggested to account for the higher hydrosilylation efficiency on MaCE PSi. Optimization of Pt-assisted chemical etching parameters suggested a 7-15 nm thick Pt-coating and an etching time of 3-10 min for biochip ap- plications. Scanning electron microscopy images revealed that an isotropic top meso-porous layer was beneficial for hydrosi- lylation and long-term durability under ambient conditions. To end, an example of histidine-tagged protein immobilization and microarray was illustrated. Combining the materials＇ property, surface chemistry, and micro-fabrication technology together, we envision that silicon based biochip applications have a prosperous future.
基金Project supported by the National Natural Science Foundation of China(Grant No.61271039)the Scientific Projects of Sichuan Province,China(Grant No.2015HH0016)the Natural Science Foundations of Zhejiang Province,China(Grant Nos.LQ12E02001 and Y107255)
文摘CoFe_2O_4 ferrite nanowire arrays are fabricated in porous silicon templates. The porous silicon templates are prepared via metal-assisted chemical etching with gold（Au） nanoparticles as the catalyst. Subsequently, CoFe_2O_4 ferrite nanowires are successfully synthesized into porous silicon templates by the sol–gel method. The magnetic hysteresis loop of nanowire array shows an isotropic feature of magnetic properties. The coercivity and squareness ratio（M_r/M_s） of ensemble nanowires are found to be 630 Oe（1 Oe = 79.5775 A·m^（-1） and 0.4 respectively. However, the first-order reversal curve（FORC） is adopted to reveal the probability density function of local magnetostatic properties（i.e., interwire interaction field and coercivity）. The FORC diagram shows an obvious distribution feature for interaction field and coercivity. The local coercivity with a value of about 1000 Oe is found to have the highest probability.
基金Project supported by the National Natural Science Foundation of China(Grant No.51272246)the Scientific and Technological Research Foundation of Anhui Province,China(Grant No.12010202035)
文摘Highly ordered silicon nanorod（Si NR） arrays with controllable geometry are fabricated via nanosphere lithography and metal-assisted chemical etching. It is demonstrated that the key to achieving a high-quality metal mask is to construct a non-close-packed template that can be removed with negligible damage to the mask. Hydrophobicity of Si NR arrays of different geometries is also studied. It is shown that the nanorod structures are effectively quasi-hydrophobic with a contact angle as high as 142°, which would be useful in self-cleaning nanorod-based device applications.
基金support of this work from the NSFC (Nos. 51504117, 61764009 and 51762043)Yunnan Applied Basic Research Project (No. Y0120150138)Research Fund of Yunnan Province Collaborative Innovation Center (No. 2014XTZS009)
文摘Nanostructures of silicon are gradually becoming hot candidate due to outstanding capability for trapping light and improving conversion efficiency of solar cell. In this paper, silicon nanowires（SiNWs） and silicon inverted pyramid arrays（SiIPs） were introduced on surface of Gr-Si solar cell through silver and copper-catalyzed chemical etching, respectively. The effects of SiNWs and SiIPs on carrier lifetime, optical properties and efficiency of Gr-SiNWs and Gr-SiIPs solar cells were systematically analyzed. The results show that the inverted pyramid arrays have more excellent ability for balancing antireflectance loss and surface area enlargement. The power conversion efficiency（PCE） and carrier lifetime of Gr-SiIPs devices respectively increase by 62% and 34% by comparing with that of Gr-SiNWs solar cells. Finally, the Gr-SiIPs cell with PCE of 5.63% was successfully achieved through nitric acid doping. This work proposes a new strategy to introduce the inverted pyramid arrays for improving the performance of Gr-Si solar cells.
基金The authors acknowledge the support of the California Energy Commission,Stanford Natural Gas Initiative,and Stanford Hydrogen Focus Group.Part of this work was performed at the Stanford Nano Shared Facilities(SNSF),supported by the National Science Foundation under award ECCS-1542152.
文摘On-demand hydrogen generation is desired for fuel cells,energy storage,and clean energy applications.Silicon nanowires(SiNWs)and nanoparticles(SiNPs)have been reported to generate hydrogen by reacting with water,but these processes usually require external assistance,such as light,electricity or catalysts.Herein,we demonstrate that a porous SiNWs array,which is fabricated via the metal-assisted anodic etching(MAAE)method,reacts with water under ambient and dark conditions without any energy inputs.The reaction between the SiNWs and water generates hydrogen at a rate that is about ten times faster than the reported rates of other Si nanostructures.Two possible sources of enhancement are discussed:SiNWs maintain their high specific surface area as they don’t agglomerate,and the intrinsic strain of the nanowires promotes the reactivity.Moreover,the porous SiNWs array is portable,reusable,and environmentally friendly,yielding a promising route to produce hydrogen in a distributed manner.
文摘In this study, we report that height-controlled vertically etched silicon nano- column arrays （vSNAs） induce strong growth cone-to-substrate coupling and accelerate in vitro neurite development while preserving the essential features of initial neurite formation. Large-scale preparation of vSNAs with flat head morphology enabled the generation of well-controlled topographical stimulation without cellular impalement. A systematic analysis on topography- induced variations on cellular morphology and cytoskeletal dynamics was conducted. In addition, neurite development on the grid-patterned vSNAs exhibited preferential adhesion to the nanostructured region and outgrowth directionality. The arrangement of cytoskeletal proteins and the expression of a focal adhesion complex indicated that a strong coupling existed between the underlying nanocolumns and growth cones. Furthermore, the height-controlled nanocolumn substrates differentially modulated neurite polarization and elongation. Our findings provide an important insight into neuron-nanotopography interactions and their role in cell adhesion and neurite development.
