In this study,we investigate an innovative hybrid structure of silicon nanowires(SiNWs)coated with polyaniline(PANI):metal oxide(MO_(x))nanoparticles,i.e.,WO_(3)and TiO_(2),for respiratory sensing.To date,few attempts...In this study,we investigate an innovative hybrid structure of silicon nanowires(SiNWs)coated with polyaniline(PANI):metal oxide(MO_(x))nanoparticles,i.e.,WO_(3)and TiO_(2),for respiratory sensing.To date,few attempts have been made to utilize such hybrid structures for that application.The Si NWs were fabricated using metal-assisted chemical etching(MACE),whereas PANI:MO_(x)was deposited using chemical oxidative polymerization.The structures were characterized using Raman spectroscopy,X-ray diffraction,and scanning electron microscopy.The sensing characteristics revealed that the hybrid sensor exhibited a considerably better response than pure Si NWs:MO_(x)and Si NWs:PANI.Such an enhancement in sensitivity is attributed to the formation of a p-n heterojunction between PANI and MO_(x),the wider conduction channel provided by PANI,increased porosity in SiNWs/PANI:WO_(3)hybrid structures,which creates active sites,increased oxygen vacancies,and the large surface area compared to that available in pure MO_(x)nanoparticles.Furthermore,less baseline drift and increased sensor stability were established for the SiNWs structure coated with PANI:WO_(3),as compared to PANI:TiO_(2).展开更多
A novel carbon matrix/silicon nanowires(SiNWs) heterogeneous block was successfully produced by dispersing SiNWs into templated carbon matrix via a modified evaporation induced self-assembly method. The heterogeneous ...A novel carbon matrix/silicon nanowires(SiNWs) heterogeneous block was successfully produced by dispersing SiNWs into templated carbon matrix via a modified evaporation induced self-assembly method. The heterogeneous block was determined by X-ray diffraction, Raman spectra and scanning electron microscopy. As an anode material for lithium batteries, the block was investigated by cyclic voltammograms(CV), charge/discharge tests, galvanostatic cycling performance and A. C. impedance spectroscopy. We show that the SiNWs disperse into the framework, and are nicely wrapped by the carbon matrix. The heterogeneous block exhibits superior electrochemical reversibility with a high specific capacity of 529.3 mAh/g in comparison with bare SiNWs anode with merely about 52.6 mAh/g capacity retention. The block presents excellent cycle stability and capacity retention which can be attributed to the improvement of conductivity by the existence of carbon matrix and the enhancement of ability to relieve the large volume expansion of SiNWs during the lithium insertion/extraction cycle. The results indicate that the as-prepared carbon matrix/SiNWs heterogeneous block can be an attractive and potential anode material for lithium-ion battery applications.展开更多
Nanowire field effect transistors can be modeled for ultrasensitive charge detection based bio- or chemical sensors. As critical dimensions of the nanowire sensor can be of the same order of size of biological molecul...Nanowire field effect transistors can be modeled for ultrasensitive charge detection based bio- or chemical sensors. As critical dimensions of the nanowire sensor can be of the same order of size of biological molecules or chemical species yielding exceptional sensing possibilities. In addition, the large surface/volume ratio will give high sensitivities simply because surface effects dominate over bulk properties. Thus, we modeled Si nanowire with different geometries in the different chemical environment using NEGF approach. To analyze the performance, the sensitivity of Si nanowire with different cross sections including circular, rectangular, and triangular is derived by two definitions. It is calculated that the sensitivity of Si nanowire with different structures is a function of geometrical parameters and doping density. It is illustrated that the sensitivity varies inversely with cross-section area, doping density, and also the length of nanowire.展开更多
Silicon nano-wires (SiNWs) and boron nitride nano-tubules (BN-NTs) were successfully synthesized by excimer laser ablation at high temperature. These one-dimensional nano-materials synthesized by this method have a ve...Silicon nano-wires (SiNWs) and boron nitride nano-tubules (BN-NTs) were successfully synthesized by excimer laser ablation at high temperature. These one-dimensional nano-materials synthesized by this method have a very high yield, a uniform diameter distribution, and a high purity. Micro-structures of these nano-materials were investigated by transmission electron microscopy (TEM). The SiNWs have a high density of structural defects of microtwin, stacking faults, and low-angle boundary, which are closely related to the formation of SiNWs and the determination of morphology of the nano-wires. BN-NTs are mainly single atomic-layered and the outer surface of tubules is clean without any attachment. The formation of single atomic-layered tubule is attributed to the catalyst effect which makes the axial rate of BN-NTs much higher than the radial growth展开更多
We explore 10-nm wide Si nanowire （SiNW） field-effect transistors （FETs） for logic applications, via the fabrication and testing of SiNW-based ring oscillators. We report on SiNW surface treatments and dielectric ...We explore 10-nm wide Si nanowire （SiNW） field-effect transistors （FETs） for logic applications, via the fabrication and testing of SiNW-based ring oscillators. We report on SiNW surface treatments and dielectric annealing, for producing SiNW FETs that exhibit high performance in terms of large on/off-state current ratio （-10s）, low drain-induced barrier lowering （-30 mV） and low subthreshold swing （-80 mV/decade）. The performance of inverter and ring-oscillator circuits fabricated from these nanowire FETs are also explored. The inverter demonstrates the highest voltage gain （-148） reported for a SiNW-based NOT gate, and the ring oscillator exhibits near rail-to-rail oscillation centered at 13.4 MHz. The static and dynamic characteristics of these NW devices indicate that these SiNW-based FET circuits are excellent candidates for various high-performance nanoelectronic applications.展开更多
A silicon（SiNW） nanowire device,made by the bottom-up method,has been assembled in a MEMS device for measuring stress in cantilevers.The process for assembling a SiNW on a cantilever has been introduced.The current ...A silicon（SiNW） nanowire device,made by the bottom-up method,has been assembled in a MEMS device for measuring stress in cantilevers.The process for assembling a SiNW on a cantilever has been introduced.The current as a function of the voltage applied to a SiNW have been measured,and the different resistances before and after cantilever releasing have been observed.A parameter,η,has been derived based on the resistances.For a fixed sample,a linear relationship between η and the stress in the cantilever has been observed;and,so,it has been demonstrated that the resistance of SiNW can reflect the variation of the cantilever stress.展开更多
基金supported by the Icelandic research fund,Grant No.239987-051by Landsvirkjun-Energy Research Fund,Grant No.NYR-29-2024。
文摘In this study,we investigate an innovative hybrid structure of silicon nanowires(SiNWs)coated with polyaniline(PANI):metal oxide(MO_(x))nanoparticles,i.e.,WO_(3)and TiO_(2),for respiratory sensing.To date,few attempts have been made to utilize such hybrid structures for that application.The Si NWs were fabricated using metal-assisted chemical etching(MACE),whereas PANI:MO_(x)was deposited using chemical oxidative polymerization.The structures were characterized using Raman spectroscopy,X-ray diffraction,and scanning electron microscopy.The sensing characteristics revealed that the hybrid sensor exhibited a considerably better response than pure Si NWs:MO_(x)and Si NWs:PANI.Such an enhancement in sensitivity is attributed to the formation of a p-n heterojunction between PANI and MO_(x),the wider conduction channel provided by PANI,increased porosity in SiNWs/PANI:WO_(3)hybrid structures,which creates active sites,increased oxygen vacancies,and the large surface area compared to that available in pure MO_(x)nanoparticles.Furthermore,less baseline drift and increased sensor stability were established for the SiNWs structure coated with PANI:WO_(3),as compared to PANI:TiO_(2).
基金supported by the grants from the National Natural Science Foundation of China(Nos.51002129,51172191 and 11074211)the National Basic Research Program of China(2012CB921303)+2 种基金the Doctoral Program of Higher Education(No.200805300003)the Hunan Provincial InnovationFoundation for Graduate(No.CX2012B265)the Open Fund Based on Innovation Platform of Hunan Colleges and Universities(No.13K045)
文摘A novel carbon matrix/silicon nanowires(SiNWs) heterogeneous block was successfully produced by dispersing SiNWs into templated carbon matrix via a modified evaporation induced self-assembly method. The heterogeneous block was determined by X-ray diffraction, Raman spectra and scanning electron microscopy. As an anode material for lithium batteries, the block was investigated by cyclic voltammograms(CV), charge/discharge tests, galvanostatic cycling performance and A. C. impedance spectroscopy. We show that the SiNWs disperse into the framework, and are nicely wrapped by the carbon matrix. The heterogeneous block exhibits superior electrochemical reversibility with a high specific capacity of 529.3 mAh/g in comparison with bare SiNWs anode with merely about 52.6 mAh/g capacity retention. The block presents excellent cycle stability and capacity retention which can be attributed to the improvement of conductivity by the existence of carbon matrix and the enhancement of ability to relieve the large volume expansion of SiNWs during the lithium insertion/extraction cycle. The results indicate that the as-prepared carbon matrix/SiNWs heterogeneous block can be an attractive and potential anode material for lithium-ion battery applications.
文摘Nanowire field effect transistors can be modeled for ultrasensitive charge detection based bio- or chemical sensors. As critical dimensions of the nanowire sensor can be of the same order of size of biological molecules or chemical species yielding exceptional sensing possibilities. In addition, the large surface/volume ratio will give high sensitivities simply because surface effects dominate over bulk properties. Thus, we modeled Si nanowire with different geometries in the different chemical environment using NEGF approach. To analyze the performance, the sensitivity of Si nanowire with different cross sections including circular, rectangular, and triangular is derived by two definitions. It is calculated that the sensitivity of Si nanowire with different structures is a function of geometrical parameters and doping density. It is illustrated that the sensitivity varies inversely with cross-section area, doping density, and also the length of nanowire.
文摘Silicon nano-wires (SiNWs) and boron nitride nano-tubules (BN-NTs) were successfully synthesized by excimer laser ablation at high temperature. These one-dimensional nano-materials synthesized by this method have a very high yield, a uniform diameter distribution, and a high purity. Micro-structures of these nano-materials were investigated by transmission electron microscopy (TEM). The SiNWs have a high density of structural defects of microtwin, stacking faults, and low-angle boundary, which are closely related to the formation of SiNWs and the determination of morphology of the nano-wires. BN-NTs are mainly single atomic-layered and the outer surface of tubules is clean without any attachment. The formation of single atomic-layered tubule is attributed to the catalyst effect which makes the axial rate of BN-NTs much higher than the radial growth
基金The authors acknowledge H. Ahmad and Y. -S. Shin for graphics assistance. This work was funded by the National Science Foundation under Grant CCF-0541461 and the Department of Energy （DE-FG02-04ER46175）. D. Tham gratefully acknowledges support by the KAUST Scholar Award.
文摘We explore 10-nm wide Si nanowire （SiNW） field-effect transistors （FETs） for logic applications, via the fabrication and testing of SiNW-based ring oscillators. We report on SiNW surface treatments and dielectric annealing, for producing SiNW FETs that exhibit high performance in terms of large on/off-state current ratio （-10s）, low drain-induced barrier lowering （-30 mV） and low subthreshold swing （-80 mV/decade）. The performance of inverter and ring-oscillator circuits fabricated from these nanowire FETs are also explored. The inverter demonstrates the highest voltage gain （-148） reported for a SiNW-based NOT gate, and the ring oscillator exhibits near rail-to-rail oscillation centered at 13.4 MHz. The static and dynamic characteristics of these NW devices indicate that these SiNW-based FET circuits are excellent candidates for various high-performance nanoelectronic applications.
基金supported by the National Natural Science Foundation of China (No. 60876078)the Funding Project for Academic Human Resources Development in Institutions of Higher Learning Under the Jurisdiction of Beijing Municipality (No. PHR(IHLB))the Beijing Novel Research Star funded by the Ministry of Beijing Science and Technology (No. 2005B01)
文摘A silicon（SiNW） nanowire device,made by the bottom-up method,has been assembled in a MEMS device for measuring stress in cantilevers.The process for assembling a SiNW on a cantilever has been introduced.The current as a function of the voltage applied to a SiNW have been measured,and the different resistances before and after cantilever releasing have been observed.A parameter,η,has been derived based on the resistances.For a fixed sample,a linear relationship between η and the stress in the cantilever has been observed;and,so,it has been demonstrated that the resistance of SiNW can reflect the variation of the cantilever stress.
