Developing wireless nanodevices and nanosystems is of critical importance for sensing, medical science, environmental/infrastructure monitoring, defense technology and even personal electronics. It is highly desirable...Developing wireless nanodevices and nanosystems is of critical importance for sensing, medical science, environmental/infrastructure monitoring, defense technology and even personal electronics. It is highly desirable for wireless devices to be self-powered without using battery, without which most of the sensor network may be impossible. The pie- zoelectric nanogenerators have the potential to serve as self-sufficient power sources for micro/nano systems. For wurtzite structures that have non-central symmetry, such as ZnO, GaN and InN, a piezoelectric potential (piezopotential) is created in the crystal by applying a strain. The nanogenerator is invented by using the piezopotential as the driving force for electrons to flow in respond to a dynamic straining of piezoelectric nanowires. A gentle straining can produce an output voltage of up to 20 - 50 V from an integrated nanogenerator. Furthermore, piezopotential in the wurtzite structure can serve as gate voltage that can effectively tune/control the charge transport across an interface/junction; electronics fabricated based on such a mechanism is coined as piezotronics, with applications in force/pressure triggercd/controlled electronic devices, sensors, logic units and memory. By using the piezotronic effect, it is showed that the optoelectronic devices fabricated using wurtzite materials can have superior performance as solar cell, photon detector and light emitting diode. Piezotronie is likely to serve as "mechanosensation" for directly interfacing biomechanieal action with silicon based technology and active flexible electronics. The paper gives a brief review about the basis of nanogenertors and piezotronics and their potential applications in smart MEMS (micro-electro-mechanical systems).展开更多
In this paper, we derive a unified scattering theory model for current noise based on the equivalent contact model of the scattering region. Our model seamlessly covers the whole range of transport regimes from cohere...In this paper, we derive a unified scattering theory model for current noise based on the equivalent contact model of the scattering region. Our model seamlessly covers the whole range of transport regimes from coherent transport to incoherent transport and it also includes the effects of Pauli exclusion and Coulomb interaction on shot noise.展开更多
Transparent conductive electrodes play a significant role in the fabrication and development of optoelectronic devices. As next generation optoelectronic devices tend towards mobile and wearable devices, the added att...Transparent conductive electrodes play a significant role in the fabrication and development of optoelectronic devices. As next generation optoelectronic devices tend towards mobile and wearable devices, the added attribute of flexibility or stretchability for these electrodes becomes increasingly important. However, mechanical requirements aside, transparent conductive electrodes must still retain high transparency and conductivity, with the metrics for these parameters being compared to the standard, indium tin oxide. In the search to replace indium tin oxide, two materials that have risen to the forefront are carbon nanotubes and silver nanowires due to their high transparency, conductivity, mechanical compliance, and ease of fabrication. This review highlights recent innovations made by our group in electrodes utilizing carbon nanotubes and silver nanowires, in addition to the use of these electrodes in discrete devices and integrated systems.展开更多
A simple and effective method for the preparation of amphiphilic graphene(AG)is presented under an organic solvent-free synthetic condition.The synthetic route first involves a cyclization reaction between carboxylic ...A simple and effective method for the preparation of amphiphilic graphene(AG)is presented under an organic solvent-free synthetic condition.The synthetic route first involves a cyclization reaction between carboxylic groups on graphene oxide and the amino groups on 5,6-diaminopyrazine-2,3-dicarbonitrile,and subsequent reduction by hydrazine.Results of UV-vis spectroscopy,Fourier transformed infrared spectroscopy(FT-IR),X-ray photoelectron spectroscopy(XPS),thermogravimetric analysis(TGA)and Raman spectroscopy have confirmed that the covalent functionalization of graphene can be achieved through the formation of imidazo[4,5-b]pyrazine on the graphene sheets.As a result,AG can be successfully dispersed in water and common organic solvents.This work successfully provides a facile and efficient way to fabricate AG and may extend the potential applications of graphene-based materials in nanoelectronic devices,polymer fillers and biological field.展开更多
Direct integration of high-mobility III-V compound semiconductors with existing Si-based complementary metal-oxide-semiconductor (CMOS) processing platforms presents the main challenge to increasing the CMOS perform...Direct integration of high-mobility III-V compound semiconductors with existing Si-based complementary metal-oxide-semiconductor (CMOS) processing platforms presents the main challenge to increasing the CMOS performance and the scaling trend. Silicon hetero-nanowires with integrated III-V segments are one of the most promising candidates for advanced nano-optoelectronics, as first demonstrated using molecular beam epitaxy techniques. Here we demonstrate a novel route for InAs/Si hybrid nanowire fabrication via millisecond range liquid-phase epitaxy regrowth using sequential ion beam implantation and flash-lamp annealing. We show that such highly mismatched systems can be monolithically integrated within a single nanowire. Optical and microstructural investigations confirm the high quality hetero-nanowire fabrication coupled with the formation of atomically sharp interfaces between Si and InAs segments. Such hybrid systems open new routes for future high-speed and multifunctional nanoelectronic devices on a single chip.展开更多
The noble metal nanoparticles, such as gold, silver and copper, has been widely incorporated into the photoelectronic devices acting as a light-harvesting an- tenna and enhancing photocurrents through their light scat...The noble metal nanoparticles, such as gold, silver and copper, has been widely incorporated into the photoelectronic devices acting as a light-harvesting an- tenna and enhancing photocurrents through their light scattering or localized surface plasmon resonance effects. Here, this article presented the investigations into the use of gold nanocrystals to realize the plasmon-enhanced photocurrent generation in TiO2 nanorod-based quantum dots-sensitized solar cells (QDSSCs). By introducing the gold nanocrystals, the short-circuit current density (Jsc) of QDSSCs was enhanced more than 10 % from 7.788 to 8.574 mA/cm^2 due to the direct injection of hot electrons from the gold nanocrystals to the photoanode. In order to confirm such conclusion, composite Au/TiO2 nanostructure was also fabricated. Indeed, the hot electrons injection resulted photocurrent density of ~5 mA/cm^2 was clearly observed under the visible light irradiation.展开更多
In present paper, the non-equilibrium Green function(NEGF) method along with the density functional theory(DFT) are used to investigate the effect of width on transport and electronic properties of armchair graphyne(...In present paper, the non-equilibrium Green function(NEGF) method along with the density functional theory(DFT) are used to investigate the effect of width on transport and electronic properties of armchair graphyne(γ-graphyne) nanoribbons. The results show that all the studied nanoribbons are semiconductor and their band gaps decrease as the widths of nanoribbons increase, which will result in increasing current at a certain voltage. Also our results show the promising application of armchair graphyne nanoribbons in nano-electrical devices.展开更多
文摘Developing wireless nanodevices and nanosystems is of critical importance for sensing, medical science, environmental/infrastructure monitoring, defense technology and even personal electronics. It is highly desirable for wireless devices to be self-powered without using battery, without which most of the sensor network may be impossible. The pie- zoelectric nanogenerators have the potential to serve as self-sufficient power sources for micro/nano systems. For wurtzite structures that have non-central symmetry, such as ZnO, GaN and InN, a piezoelectric potential (piezopotential) is created in the crystal by applying a strain. The nanogenerator is invented by using the piezopotential as the driving force for electrons to flow in respond to a dynamic straining of piezoelectric nanowires. A gentle straining can produce an output voltage of up to 20 - 50 V from an integrated nanogenerator. Furthermore, piezopotential in the wurtzite structure can serve as gate voltage that can effectively tune/control the charge transport across an interface/junction; electronics fabricated based on such a mechanism is coined as piezotronics, with applications in force/pressure triggercd/controlled electronic devices, sensors, logic units and memory. By using the piezotronic effect, it is showed that the optoelectronic devices fabricated using wurtzite materials can have superior performance as solar cell, photon detector and light emitting diode. Piezotronie is likely to serve as "mechanosensation" for directly interfacing biomechanieal action with silicon based technology and active flexible electronics. The paper gives a brief review about the basis of nanogenertors and piezotronics and their potential applications in smart MEMS (micro-electro-mechanical systems).
基金This research was financially supported by Scientific Research Fund of Shaanxi Provincial Education Department (Grant No. 2013K1115) ,the National Natural Science Foundation of China (Grant No. 61106062), the Fundamental Research Funds for the Central Universities (Grant No. K50511050007), and the Fundamental Research Funds for AnKang University (Grant No. AYQDZR201206).
文摘In this paper, we derive a unified scattering theory model for current noise based on the equivalent contact model of the scattering region. Our model seamlessly covers the whole range of transport regimes from coherent transport to incoherent transport and it also includes the effects of Pauli exclusion and Coulomb interaction on shot noise.
基金supported in part by the Air Force Office of Scientific Research (FA9550-12-1-0074, Dr. Charles Lee)
文摘Transparent conductive electrodes play a significant role in the fabrication and development of optoelectronic devices. As next generation optoelectronic devices tend towards mobile and wearable devices, the added attribute of flexibility or stretchability for these electrodes becomes increasingly important. However, mechanical requirements aside, transparent conductive electrodes must still retain high transparency and conductivity, with the metrics for these parameters being compared to the standard, indium tin oxide. In the search to replace indium tin oxide, two materials that have risen to the forefront are carbon nanotubes and silver nanowires due to their high transparency, conductivity, mechanical compliance, and ease of fabrication. This review highlights recent innovations made by our group in electrodes utilizing carbon nanotubes and silver nanowires, in addition to the use of these electrodes in discrete devices and integrated systems.
基金supported by the NSFC for Excellent Young Scholars(Grant No.21322402)National Natural Science Foundation of China(Grant Nos.21274064,61204095,51173081)+2 种基金the Program for New Century Excellent Talents in University(Grant No.NCET-11-0992)Natural Science Foundation of Jiangsu Province,China(Grant Nos.BK2011761,BK2012431,BK2009025)NJUPT(Grant No.NY211022)
文摘A simple and effective method for the preparation of amphiphilic graphene(AG)is presented under an organic solvent-free synthetic condition.The synthetic route first involves a cyclization reaction between carboxylic groups on graphene oxide and the amino groups on 5,6-diaminopyrazine-2,3-dicarbonitrile,and subsequent reduction by hydrazine.Results of UV-vis spectroscopy,Fourier transformed infrared spectroscopy(FT-IR),X-ray photoelectron spectroscopy(XPS),thermogravimetric analysis(TGA)and Raman spectroscopy have confirmed that the covalent functionalization of graphene can be achieved through the formation of imidazo[4,5-b]pyrazine on the graphene sheets.As a result,AG can be successfully dispersed in water and common organic solvents.This work successfully provides a facile and efficient way to fabricate AG and may extend the potential applications of graphene-based materials in nanoelectronic devices,polymer fillers and biological field.
文摘Direct integration of high-mobility III-V compound semiconductors with existing Si-based complementary metal-oxide-semiconductor (CMOS) processing platforms presents the main challenge to increasing the CMOS performance and the scaling trend. Silicon hetero-nanowires with integrated III-V segments are one of the most promising candidates for advanced nano-optoelectronics, as first demonstrated using molecular beam epitaxy techniques. Here we demonstrate a novel route for InAs/Si hybrid nanowire fabrication via millisecond range liquid-phase epitaxy regrowth using sequential ion beam implantation and flash-lamp annealing. We show that such highly mismatched systems can be monolithically integrated within a single nanowire. Optical and microstructural investigations confirm the high quality hetero-nanowire fabrication coupled with the formation of atomically sharp interfaces between Si and InAs segments. Such hybrid systems open new routes for future high-speed and multifunctional nanoelectronic devices on a single chip.
基金supported by the Program for Changjiang Scholars and Innovative Research Team in University(PCS IRT1126)the National Natural Science Foundation of China(11274093,61376061 and 61240053)
文摘The noble metal nanoparticles, such as gold, silver and copper, has been widely incorporated into the photoelectronic devices acting as a light-harvesting an- tenna and enhancing photocurrents through their light scattering or localized surface plasmon resonance effects. Here, this article presented the investigations into the use of gold nanocrystals to realize the plasmon-enhanced photocurrent generation in TiO2 nanorod-based quantum dots-sensitized solar cells (QDSSCs). By introducing the gold nanocrystals, the short-circuit current density (Jsc) of QDSSCs was enhanced more than 10 % from 7.788 to 8.574 mA/cm^2 due to the direct injection of hot electrons from the gold nanocrystals to the photoanode. In order to confirm such conclusion, composite Au/TiO2 nanostructure was also fabricated. Indeed, the hot electrons injection resulted photocurrent density of ~5 mA/cm^2 was clearly observed under the visible light irradiation.
文摘In present paper, the non-equilibrium Green function(NEGF) method along with the density functional theory(DFT) are used to investigate the effect of width on transport and electronic properties of armchair graphyne(γ-graphyne) nanoribbons. The results show that all the studied nanoribbons are semiconductor and their band gaps decrease as the widths of nanoribbons increase, which will result in increasing current at a certain voltage. Also our results show the promising application of armchair graphyne nanoribbons in nano-electrical devices.