纳光电子与光子芯片研究:发展与挑战

光子芯片被认为是“后摩尔时代”信息领域发展的核心技术之一。纳光电子学的发展为实现更高性能和更高集成度的光子芯片技术奠定了基础。同时,光子芯片对于突破电子芯片“卡脖子”的现实问题具有重要战略意义,有助于推动我国在未来光电信息产业的国际竞争中走出“缺芯”困境,并取得先发优势。基于国家自然科学基金委员会第312期“双清论坛”,本文总结了我国在纳光电子与光子芯片研究方面的重大需求,回顾了纳光电子与光子芯片领域近年来通过物理、材料、信息、制造等学科交叉融合所取得的主要进展和成就,凝炼了该领域未来5~10年的重大关键科学问题,探讨了前沿研究方向和科学基金资助战略。

硅基微纳光电子系统中光源的研究现状及发展趋势

综合微电子学及微纳光学的优势,硅基微纳光电子学正在快速走向实用阶段。与微电子制造技术兼容的微纳光子器件,包括调制器、探测器、分束器以及耦合器等均取得了重要的突破。但硅基微纳光源的研究则仍处在探索阶段。外部光源在多大程度上能代替片上光源?片上光源的最佳选择是什么?介绍、分析了目前硅基微纳光源的研究现状及进展,并对片上光源的研究趋势进行展望。

Highly Sensitive Photodetectors Based on WS_(2) Quantum Dots/GaAs Heterostructures

The performance of the photodetector is significantly impacted by the inherent surface faults in GaAs nanowires(NWs).We combined three-dimensional(3D)gallium arsenide nanowires with zero-dimensional(0D)WS_(2) quantum dot(QDs)materials in a simple and convenient way to form a heterogeneous structure.Various performance enhancements have been realized through the formation of typeⅡenergy bands in heterostructures,opening up new research directions for the future development of photodetector devices.This work successfully fabricated a high-sensitivity photodetector based on WS_(2)QDs/GaAs NWs heterostructure.Under 660 nm laser excitation,the photodetector exhibits a responsivity of 368.07 A/W,a detectivity of 2.7×10^(12)Jones,an external quantum efficiency of 6.47×10^(2)%,a low-noise equivalent power of 2.27×10^(-17)W·Hz^(-1/2),a response time of 0.3 s,and a recovery time of 2.12 s.This study provides a new solution for the preparation of high-performance GaAs detectors and promotes the development of optoelectronic devices for GaAs NWs.

Nano-Level Electron Beam Lithography

The JEOL JBX-5000LS is a vector type machine.The system hardware features an ion-pumped column,a LaB 6 electron emitter,25kV and 50kV accelerating voltage,and a turbo-pumped sample chamber.The resolution,stability,stitching and overlay of this system are evaluated.The system can write complex patterns at dimensions down to 30nm.The demonstrated overlay accuracy of this system is better than 40nm.

NiFe layered double-hydroxide nanoparticles for efficiently enhancing performance of BiVO_4 photoanode in photoelectrochemical water splitting

A bismuth vanadate(BiVO4)photoanode with a cocatalyst consisting of NiFe layered double‐hydroxide(NiFe‐LDH)nanoparticles was fabricated for photoelectrochemical(PEC)water splitting.NiFe‐LDH nanoparticles,which can improve light‐absorption capacities and facilitate efficient hole transfer to the surface,were deposited on the surface of the BiVO4 photoanode by a hydrothermal method.All the samples were characterized using X‐ray diffraction,scanning electron microscopy,and diffuse‐reflectance spectroscopy.Linear sweep voltammetry and current‐time plots were used to investigate the PEC activity.The photocurrent response of NiFe‐LDH/BiVO4 at 1.23 V vs the reversible hydrogen electrode was higher than those of Ni(OH)2/BiVO4,Fe(OH)2/BiVO4 and pure BiVO4 electrodes under visible‐light illumination.NiFe‐LDH/BiVO4 also gave a superior PEC hydrogen evolution performance.Furthermore,the stability of the NiFe‐LDH/BiVO4 photoanode was excellent compared with that of the bare BiVO4 photoanode,and offers a novel method for solar‐assisted water splitting.

Dynamic of the Dielectric Nano-Particle in Optical Tweezer Using Counter-Propagating Pulsed Laser Beams

In this article, the dynamical process of the dielectric particle in the optical tweezer using the counter-propagating Gaussian pulses is investigated by the Langevin equation concerning the Brownian motion. The temporal stabilities of particle is simulated. The influence of the duration, repetition period and delay time between pulses on stability is discussed.

Structural and optical properties of nano-spin coated sol-gel porous TiO_2 films

Three thicknesses of TiO2 films, 174, 195, and 229 nm, were deposited onto quartz substrates by sol–gel spin coating method. The as-deposited thin films were characterized by nano-crystallite with different sizes (19–46 nm) and relatively high porous structure. Optical constants were determined and showed the lowest refractive index of 1.66 for the as-prepared films that ever reported till now. Obtained results were discussed through current theoretical ideas.

Gold/monolayer graphitic carbon nitride plasmonic photocatalyst for ultrafast electron transfer in solar-to-hydrogen energy conversion

Gold(Au)plasmonic nanoparticles were grown evenly on monolayer graphitic carbon nitride(g‐C3N4)nanosheets via a facile oil‐bath method.The photocatalytic activity of the Au/monolayer g‐C3N4 composites under visible light was evaluated by photocatalytic hydrogen evolution and environmental treatment.All of the Au/monolayer g‐C3N4 composites showed better photocatalytic performance than that of monolayer g‐C3N4 and the 1%Au/monolayer g‐C3N4 composite displayed the highest photocatalytic hydrogen evolution rate of the samples.The remarkable photocatalytic activity was attributed largely to the successful introduction of Au plasmonic nanoparticles,which led to the surface plasmon resonance(SPR)effect.The SPR effect enhanced the efficiency of light harvesting and induced an efficient hot electron transfer process.The hot electrons were injected from the Au plasmonic nanoparticles into the conduction band of monolayer g‐C3N4.Thus,the Au/monolayer g‐C3N4 composites possessed higher migration and separation efficiencies and lower recombination probability of photogenerated electron‐hole pairs than those of monolayer g‐C3N4.A photocatalytic mechanism for the composites was also proposed.

Microstructure and abrasive wear behaviour of anodizing composite films containing Si C nanoparticles on Ti6Al4V alloy

Anodized composite films containing Si C nanoparticles were synthesized on Ti6Al4 V alloy by anodic oxidation procedure in C4O6H4Na2 electrolyte. Scanning electron microscopy(SEM), energy dispersive spectroscopy(EDS) and X-ray photoelectron spectroscopy(XPS) were employed to characterize the morphology and composition of the films fabricated in the electrolytes with and without addition of Si C nanoparticles. Results show that Si C particles can be successfully incorporated into the oxide film during the anodizing process and preferentially concentrate within internal cavities and micro-cracks. The ball-on-disk sliding tests indicate that Si C-containing oxide films register much lower wear rate than the oxide films without Si C under dry sliding condition. Si C particles are likely to melt and then are oxidized by frictional heat during sliding tests. Potentiodynamic polarization behavior reveals that the anodized alloy with Si C nanoparticles results in a reduction in passive current density to about 1.54×10-8 A/cm2, which is more than two times lower than that of the Ti O2 film(3.73×10-8 A/cm2). The synthesized composite film has good anti-wear and anti-corrosion properties and the growth mechanism of nanocomposite film is also discussed.

Silver Nanoparticles Synthesized by Laser Ablation in Acetone： Influence of Ablation Time and Their Reactivity with Oxygen in the Air

In this work, a method is proposed to control silver nanoparticle dimensions produced by laser ablation varying the ablation time and introducing a sonication phase between ablation and the successive deposition on the substrate. The absorption spectra during laser ablation show a main band, which identifies the dimensions of main particles. The appearance of secondary bands indicates the beginning of an aggregation process with the formation of a small concentration of particles which are spheroid in shape. SEM （secondary electron microscope） images of particle produced with different ablation times confirm the results of absorption measurements. X-ray photoelectron spectroscopy and cathodo-luminescence spectroscopy indicate a high reactivity of the nanoparticles deposited on a substrate. They react with oxygen in the air forming an oxide layer which reveals a luminescence in the blue region.

Friction and Wear Behaviors of Nano-Silicates in Water

Nano-metric magnesium silicate and zinc silicate with particle size of about 50-70nm were prepared in water by the method of chemical deposition. The antiwear and friction reducing abilities of the nano-silicates, as well as their composites with oleic acid tri-ethanolamine （OATEA）, were evaluated on a four-ball friction tester. The topographies and tribochemical features of the worn surfaces were analyzed by scanning electron microscope （SEM） and X-ray photoelectron spectroscope （XPS）. Results show that nano-silicates alone provide poor antiwear and friction reducing abilities in water, but exhibits excellent synergism with OATEA in reducing friction and wear. The synergism in reducing friction and wear between nano- silicates and OATEA does exist almost regardless of particte sizes and species, and may be attributed, on one hand, to the formation of an adsorption film of OATEA, and, on the other hand, to the formation oftribochemical species of silicon dioxide and iron oxides on the friction surfaces. Tribo-reactions and tribo-adsorptions of nano-silicates and OATEA would produce hereby an effective composite boundary lubrication film, which could efficiently enhance the anti-wear and friction-reducing abilities of water.

Light emitting devices based on Si nanoclusters:the integration with a photonic crystal and electroluminescence properties

We present the properties and potentialities of light emitting devices based on amorphous Si nanoclusters. Amorphousnanostructures may constitute an interesting alternative to Si nanocrystals for the monolithic integration of optical andelectrical functions in Si technology. In fact, they exhibit an intense room temperature electroluminescence (EL). The ELproperties of these devices have been studied as a function of current and of temperature. Moreover, to improve theextraction efficiency of the light, we have integrated the emitting system with a 2D photonic crystal structure opportunelyfabricated by using conventional optical lithography to reduce the total internal reflection of the emitted light. The extractionefficiency in such devices increases by a factor of 4 at a resonance wavelength.

Anisotropic gold nanoparticles: Preparation and applications in catalysis

Despite the high amount of scientific work dedicated to the gold nanoparticles in catalysis, most of the research has been performed utilising supported nanoparticles obtained by traditional impreg‐nation of gold salts onto a support, co‐precipitation or deposition‐precipitation methods which do not benefit from the recent advances in nanotechnologies. Only more recently, gold catalyst scien‐tists have been exploiting the potential of preforming the metal nanoparticles in a colloidal suspen‐sion before immobilisation with great results in terms of catalytic activity and the morphology con‐trol of mono‐and bimetallic catalysts. On the other hand, the last decade has seen the emergence of more advanced control in gold metal nanoparticle synthesis, resulting in a variety of anisotropic gold nanoparticles with easily accessible new morphologies that offer control over the coordination of surface atoms and the optical properties of the nanoparticles （tunable plasmon band） with im‐mense relevance for catalysis. Such morphologies include nanorods, nanostars, nanoflowers, den‐dritic nanostructures or polyhedral nanoparticles to mention a few. In addition to highlighting newly developed methods and properties of anisotropic gold nanoparticles, in this review we ex‐amine the emerging literature that clearly indicates the often superior catalytic performance and amazing potential of these nanoparticles to transform the field of heterogeneous catalysis by gold by offering potentially higher catalytic performance, control over exposed active sites, robustness and tunability for thermal‐, electro‐and photocatalysis.

Novel fluorescence sensor based on covalent immobilization of 3-amino-9-ethylcarbazole via electrostatically assembled gold nanoparticle layer

A novel technique of immobilizing indicator dyes by electrostatic adsorption and covalent bonding to fabricate optical sensors was developed.3-Amino-9-ethylcarbazole(AEC)was attached to the outmost surface of quartz glass slide via aminosilanizing the slide,crosslinking chitosan,adsorbing Au nanoparticle,self-assembling HS(CH2)11OH,and coupling AEC.Thus, an AEC-immobilized optical sensor was obtained.The sensor exhibits a wide linear response range from 7.0×10- 7to 1.0×10 -4 mol/L and a correlation coefficient of 0.995 9 for the detection of 2-nitrophenol.The detection limit and response time of the sensor are 1.0×10- 7mol/L and less than 10 s,respectively.The fluorescence intensity of the used sensor can be restored to the blank value by simply rinsing with blank buffer.A very effective matrix for immobilizing indicator dye is provided by the proposed technique, which is adaptable to other indicator dyes with amino groups besides AEC.

Fabrication of SPES/Nano-TiO_2 Composite Ultrafiltration Membrane and Its Anti-fouling Mechanism

Membrane fouling is one of the major obstacles for reaching a high flux over a prolonged period of ultrafiltration（UF）process.In this study,a sulfonated-polyethersulfone（SPES）/nano-TiO2 composite UF membrane with good anti-fouling performance was fabricated by phase inversion and self-assembly methods.The TiO2 nanoparticle self-assembly on the SPES membrane surface was confirmed by X-ray photoelectron spectroscopy （XPS）and FT-IR spectrometer.The morphology and hydrophilicity were characterized by scanning electron microscopy（SEM）,atomic force microscopy（AFM）and contact angle goniometer,respectively.The anti-fouling mechanism of composite UF membrane was discussed through the analysis of the micro-structure and component of UF membrane surface.The results showed that the TiO2 content and the micro-structure of the composite UF membrane surface had great influence on the separation and anti-fouling performance.

Studies on Preparation and Properties of Proton Exchange Membranes Based on Phosphotungstic Acid/Silica and Polysulfonamide

Membranes formed by polysulfonamide(PSA)and phosphotungstic acid(PWA)supported on nano-silica have been prepared.Fourier transform infrared spectra(FTIR)and thermogravimetric analysis(TGA)were used to characterize the structure and thermal properties of obtained membranes.The analyses of water uptake,proton conductivity and mechanical properties of the membranes revealed that PWA and silica produced a beneficial effect on proton conduction of the membranes.The membranes with 50 wt% of PWA-SiO2 /PSA were mechanically stable and gave proton conductivity of 2.57×10-2 S·cm-1 at 90℃ and 100% relative humidity.According to the obtained results,PWA and SiO2 doped PSA is a promising material for proton exchange membrane.

Solvothermal Synthesis and Optical Performance of One-dimensional Strontium Hydroxyapatite Nanorod

One-dimensional strontium hydroxyapatite （Sr-HAp） nanorods were successfully synthesized by a simple solvothermal method. The products were characterized via X-ray diffraction （XRD）, Fourier transform infrared （.FT-IR）, .cold field emission.sc.anning.elec.tron microscopy_.（FESEM）, transmission.electron microscopy （TEM）,photoluminescence （PL） excitation and emission spectra. The experimental results indicated that oleic acid as a surfactant played a key role in confining the growth of the Sr-HAp powders. A possible formation mechanism of the one-dimensional nanorod was proposed and elaborated. Moreover, the as-obtained Sr-HAp samoles showed an intense and bright emission band centered at 460 nm under long-wavelength UV light excitation and the contents of NaOH used in the synthetic process had an obvious impact on the optical performance of Sr-HAp powders. The possible luminescent mechanism of the Sr-HAp samples was discussed.

Study of Dye Absorption in Carbon Nanotube-Titanium Dioxide Heterostructures

In this work, the authors present a study of dye absorption in TiO2 doped with CNTs （carbon nanotubes）. Absorption decreases exponentially with the increase of CNTs in the film, while morphological characterization, conducted by SEM （scanning electron microscope） and TEM （transmission electron microscope） microscopes, suggests that this behavior is strongly related to morphological structure of grown films. For CNTs amounts greater than 1%, the authors observe the formation of CNTs clusters randomly distribute on TiO2 bulk, which strongly reduces the film porosity quenching the dye absorption. Comparison with optical properties of CNT/TiO2 filmstudied in the previous work, suggest that the best level of doping is with 0.5% of CNTs. FTIR （Fourier transform infrared spectroscopy） measurements conducted on a series of pristine and doped samples clearly indicate the absence of change in allotropic species of TiO2, while AFM （atomic force microscope） analysis indicates that the sample roughness strongly changes with doping, preventing the dye adsorption. Finally, measurements of cell efficiency indicate an increase of 5% in cells with 0.5% of CNT doping and a decrease for greater values.

Surface Structure, Spectroscopic and Photocatalytic Activity Study of Polyaniline/TiO2 Nanocomposites

PANI （polyaniline） as a promising conducting polymer and photosensitizer has been used to prepare PANI/TiO2 （polyaniline/TiO2） nanocomposite as photocatalyst. TiO2 nanoparticles with size of 5-100 nm were encapsulated by PANI via the ＂in situ＂ polymerization of aniline on the surface of TiO2 nanoparticles. IR, SEM, EPR techniques were used to characterize the mechanism of electron interaction in PANI/TiO2 nanocomposite. The resulting PANI-modified TiO2 composites exhibit significantly higher photocatalytic activity than that of neat PANI on degradation of MB （methylen blue） aqueous solution under UV irradiation.

Simulation of Influence of Partially Coherent Gaussian Laser Beam on Gradient Force Acting on Dielectric Nanoparticle inside Random Medium

The partially coherent beams propagating through random media have been used in the past to enhance effect of nonlinear optical interaction. Moreover, after propagation through a random （or turbulent） medium the coherent beam becomes a partially coherent one. In this research, the analytical formula for the average intensity of Gaussian beam propagating through random medium is derived and the influence of coherent partiality on optical gradient force acting on dielectric particle rounded by a random media is investigated.