Fabrication of Nanoscale Step Height Structure Using Atomic Layer Deposition Combined with Wet Etching

The current techniques used for the fabrication of nanosteps are normally done by layer growth and then ion beam thinning. There are also extra films grown on the step surfaces in order to reduce the roughness. So the whole process is time consuming. In this paper, a nanoscale step height structure is fabricated by atomic layer deposition （ALD） and wet etching techniques. According to the traceable of the step height value, the fabrication process is controllable. Because ALD technology can grow a variety of materials, aluminum oxide （Al2O3） is used to fabricate the nanostep. There are three steps of Al2O3 in this structure including 8 nm, 18 nm and 44 inn. The thickness of Al2O3 film and the height of the step are measured by anellipsometer. The experimental results show that the thickness of Al2O3 film is consistent with the height of the step. The height of the step is measured by AFM. The measurement results show that the height is related to the number of cycles of ALD and the wet etching time. The bottom and the sidewall surface roughness are related to the wet etching time. The step height is calibrated by Physikaliseh-Technische Bundesanstalt （PTB） and the results were 7.5±1.5 nm, 15.5±2.0 nm and 41.8±2.1 nm, respectively. This research provides a method for the fabrication of step height at nanoscale and the nanostep fabricated is potential used for standard references.

Second-order interference of two independent and tunable single-mode continuous-wave lasers

The second-order temporal interference of two independent single-mode continuous-wave lasers is discussed by em- ploying two-photon interference in Feynman＇s path integral theory. It is concluded that whether the second-order temporal interference pattern can or cannot be retrieved via two-photon coincidence counting rate is dependent on the resolution time of the detection system and the frequency difference between these two lasers. Two identical and tunable single-mode continuous-wave diode lasers are employed to verify the predictions. These studies are helpful to understand the physics of two-photon interference with photons of different spectra.

Ultra-broadband and high-efficiency polarization conversion metasurface with multiple plasmon resonance modes

In this paper, we present a novel metasurface design that achieves a high-efficiency ultra-broadband cross polarization conversion. The metasurface is composed of an array of unit resonators, each of which combines an H-shaped structure and two rectangular metallic patches. Different plasmon resonance modes are excited in unit resonators and allow the polarization states to be manipulated. The bandwidth of the cross polarization converter is 82% of the central frequency,covering the range from 15.7 GHz to 37.5 GHz. The conversion efficiency of the innovative new design is higher than 90%.At 14.43 GHz and 40.95 GHz, the linearly polarized incident wave is converted into a circularly polarized wave.

Second-order temporal interference of two independent light beams at an asymmetrical beam splitter

The second-order temporal interference of classical and nonclassical light at an asymmetrical beam splitter is discussed based on two-photon interference in Feynman＇s path integral theory. The visibility of the second-order interference pattern is determined by the properties of the superposed light beams, the ratio between the intensities of these two light beams, and the reflectivity of the asymmetrical beam splitter. Some requirements about the asymmetrical beam splitter have to be satisfied in order to ensure that the visibility of the second-order interference pattern of nonclassical light beams exceeds the classical limit. The visibility of the second-order interference pattern of photons emitted by two independent single-photon sources is independent of the ratio between the intensities. These conclusions are important for the researches and applications in quantum optics and quantum information when an asymmetrical beam splitter is employed.

Controlling Factors of the Electric Field at the Triple Junction

The metal-dielectric-vacuum junction is defned as the triple junction owned enhanced electric field, thus this special region is regarded as the location where primary electrons emission is favored. For electron emission, triple junction could affect both the flashover breakdown of insulators and the electron emission property of ferroelectrie cathodes. In this study, we theoretically investigate the electric field enhancement in the triple-junction region. It is found that the key parameter to determine the field enhancement is the taper angle of the electrode and the relative permittivity of the dielectric. In addition, we first deduce the accurate expression of the electric field in this special region. The controlling parameters for determining the field enhancement are discussed in detail. We also discover the way to reduce the electric field of this region through simulation. The current analysis would be useful for both the electron emission enhancement and the issue of flashover breakdown.

Lithium-assisted exfoliation of pristine graphite for few-layer graphene nanosheets

一条帮助锂的途径为太古的石墨的脱落被开发了，它允许很少层 graphene nanosheets 的大规模准备。这个过程包含意外物理插入和脱落，和这个方法准备的 graphene nanosheets 揭示没受到干扰的 sp < 啜 class= “ a-plus-plus ” > 2 -hybridized 结构。可能的二拍子的圆舞机制，包含在石墨层和一个随后的 lithiation 过程的边附近被套住的否定费用，被建议在石墨夹层内解释锂的插入。如果必要，现在的脱落能被重复并且更薄(单身者或 23 层) graphene 能在大规模上被完成。这个简单过程为太古的石墨的脱落提供一个有效过程，它可能支持 graphene 的未来应用程序。

Effect of annealing temperature of Bi_(1.5)Zn_(1.0)Nb_(1.5)O_7 gate insulator on performance of ZnO based thin film transistors

The bottom-gate structure ZnO based thin film transistors （ZnO-TFTs） using Bi1.5Zn1.0Nb1.507 （BZN） thin films as gate insulator were fabricated on Pt/SiO2/Si substrate by radio frequency magnetic sputtering. We investigated the effect of annealing temperature at 300, 400, and 500℃ on the performance of BZN thin films and ZnO-TFTs. XRD measurement confirmed that BZN thin films were amorphous in nature. BZN thin films annealed at 400℃ obtain the high capacitance density of 249 nF/cm2, high dielectric constant of 71, and low leakage current density of 10^-7 A/cm2 ordoff current ratio and field effect mobility of ZnO-TFTs annealed at 400℃ are approximately one order of magnitude and two times, respectively higher than that of ZnO-TFTs annealed at 300℃. When the annealing temperature is 400℃, the electrical performance of ZnO-TFTs is enhanced remarkably. Devices obtain a low sub-threshold swing of 470 mV/dec and surface states density of 3.21×10^12cm^-2.

Enhancing the performance of poly(3-hexylthiophene)/ZnO nanorod arrays based hybrid solar cells through incorporation of a third component

Sparse ZnO nanorod arrays(NRAs)are fabricated on transparent conducting oxide coated glass substrates by using a modified liquid phase epitaxial growth method.By adjusting the polymer concentrations and the spin-coating parameters,full infiltration of poly(3-hexylthiophene)(P3HT)into the as-prepared ZnO NRAs is achieved at 130°C in vacuum.A third component is incorporated into the P3HT/ZnO NRAs ordered bulk heterojunctions(BHJs)either through ZnO surface modification with N719dye or CdS shell layer or by inclusion of a fullerene derivative into the P3HT matrix.Experimental results indicate that performances of the hybrid solar cells are improved greatly with the incorporation of a third component.However,the working principles of these third components differ from one another,according to morphology,structure,optical property,charge transfer and interfacial properties of the composite structures.An ideal device architecture for hybrid solar cells based on P3HT/ZnO NRAs ordered BHJs is proposed,which can be used as a guidance to further increase the power conversion efficiency of such solar cells.

DIELECTRIC RELAXATION IN RELAXOR FERROELECTRICS

In this review the dielectric properties of relaxor ferroelectrics are discussed and compared withthe properties of normal dielectrics and ferroelectrics. We try to draw a general picture ofdielectric relaxation starting from a textbook review of the underlying concepts and pay attentionto common behavior of relaxors rather than to the features observed in specific materials. We hopethat this general approach is beneficial to those physicists, chemists, material scientists and deviceengineers who deal with relaxors. Based on the analysis of dielectric properties, a comprehensivedefinition of relaxors is proposed: relaxors are defined as ferroelectrics in which the maximum inthe temperature dependence of static susceptibility occurs within the temperature range ofdielectric relaxation, but does not coincide with the temperature of singularity of relaxation timeor soft mode frequency.

Dielectric response and percolation behavior of Ni–P(VDF–TrFE) nanocomposites

Conductor–dielectric 0–3 nanocomposites using spherical nickel nanoparticles as filler and poly(vinylidene fluoride–trifluoroethylene)70/30 mol.%as matrix are prepared using a newly developed process that combines a solution cast and a hotpressing method with a unique configuration and creates a uniform microstructure in the composites.The uniform microstructure results in a high percolation threshold’φc(>55 vol.%).The dielectric properties of the nanocomposites at different frequencies over a temperature range from -70℃ to 135℃ are studied.The results indicate that the composites exhibit a lower electrical conductivity than the polymer matrix.It is found that the nanocomposites can exhibit an ultra-high dielectric constant,more than 1500 with a loss of about 1.0 at 1 kHz,when the Ni content(53 vol.%)is close to percolation threshold.For the nanocomposites with 50 vol.%Ni particles,a dielectric constant more than 600 with a loss less than 0.2 is achieved.It is concluded that the loss including high loss is dominated by polarization process rather than the electrical conductivity.It is also found that the appearance of Ni particles has a strong influence on the crystallization process in the polymer matrix so that the polymer is converted from a typical ferroelectric to a relaxor ferroelectric.It is also demonstrated that the widely used relationship between the dielectric constant and the composition of the composites may not be valid.

TEMPERATURE-INDEPENDENT DIELECTRIC PROPERTIES OF 0.82[0.94Bi_(0.5)Na_(0.5)TiO_(3)-0.06BaTiO_(3)]-0.18K_(0.5)Na_(0.5)NbO_(3)CERAMICS

In order to explore the high temperature stability of ceramic capacitor,we present temperatureindependent dielectric properties of 0.82[0.94Bi_(0.5)Na_(0.5)TiO_(3)-0.06BaTiO_(3)]-0.18K_(0.5)Na_(0.5)NbO_(3)(BNT-BT-18KNN)ceramics.For different sintered temperature and annealing treatment,the pseudoternary system showed aεr of 2265 at 1 kHz at 35℃with a normalized permittivity ε/ε35℃varying less than±15%from 11℃to 382℃.This pure perovskite phase with slimmer and heat proof P
E loops possessed energy density of 0.616 J/cm^(3)with a tolerance of about3%in a temperature interval ranging from 20℃to 120℃,which is higher and more temperature stable than most ceramic capacitors,such as PLZST and 0.89BNT
0.06BT
0.05KNN.This relaxor ferroelectric(at room temperature)with parabolic bipolar strain
electric(S(E))curve showed a quite low temperature dependence of positive strain with less than±6.5%tolerance from the average value of 0.091%between 20℃and 120℃,which is also more temperature stable than the same composition Zhang et al.reported.These merits demonstrate that the newly produced BNT-BT-18KNN ceramics should be a promising candidate for the development of high-temperature capacitor and actuator materials.

DC BIAS ELECTRIC FIELD DEPENDENT PIEZOELECTRICITY FOR[001]POLED Pb(In_(1/2)Nb_(1/2))O_(3)-Pb(Mg_(1/3)Nb_(2/3))O_(3)-PbTiO_(3) CRYSTALS

The longitudinal piezoelectric response of[001]poled rhombohedral and orthorhombic Pb(In_(1/2)Nb_(1/2))O_(3)-Pb(Mg_(1/3)Nb_(2/3))O_(3)-PbTiO_(3)crystals were investigated with respect to DC bias electric field,being in the range of-2-15 kV/cm.For rhombohedral crystals with compo-sitions far away from morphotropic phase boundary(MPB),the piezoelectric response generally decreased with increasing positive DC bias field,while for crystals with MPB compositions,the piezoelectric response firstly decreased and then increased as function of DC bias.The piezo-electric response was found to decrease drastically when DC bias larger than phase transition feld.On the other hand,the piezoelectric response was slightly enhanced for all the crystals as function of negative DC bias prior to the depolarization.To explain the obtained results,the field dependent piezoelectric cofficients in domain engineered crystals were analyzed based on ther-modynamic approach.

SINTERING BEHAVIOR AND MICROWAVE DIELECTRIC PROPERTIES OF NOVEL LOW TEMPERATURE FIRING Bi_(3)FeMo_(2)O_(12)CERAMIC

In the present work,a novel low temperature-ring Bi_(3)FeMo_(2)O_(12) ceramic was synthesized via the solid-state reaction method.The monoclinic Bi_(3)FeMo_(2)O_(12) phase can be formed at a low temperature 670℃.A relative density above 96%can be obtained when sintering temperature is above 800℃.The Bi_(3)FeMo_(2)O_(12) ceramic sintered at 845℃ for 2 h shows high microwave dielectric performance with a permittivity-27.2,a Qf value of 14,500GHz and a temperature coefficient of-80 ppm/℃.It might be a candidate for low temperature co-fired ceramics technology.

THE INVESTIGATION ON THE FORMATIONOF(K_(0.5)Na_(0.5))NbO_(3)PEROVSKITE PHASE IN MECHANOCHEMICAL SYNTHESIS

teviseuzobeptehberzoriLead-free(K_(0.5)Na_(0.5))NbO_(3)(KNN)nanopowder with perovskite structure was synthesized bymechanochemical synthesis method successfully.In order to investigate the perovskite phaseformation of KNN powders during the mechanochemical synthesis process,we set up three millingroutes with different transmission ratios(W_(v)/W_(p))acting on the mixed starting powders of Na_(2)CO_(3),K_(2)CO_(3)and Nb_(2)O_(5).KNN perovskite phase was not detected by XRD under the lowtransmission ratios-2 with the shock power of 273 W.When the transmission ratios wasincreased to-2.75 with the shock power of 683.4 W,KNN perovskite phase was formed aftermilling for 22 h.Based on these results it has been found,that in shock mode process(SMIP),thathigher shock power is helpful for the formation KNN perovskite phase.The critical shock powerPaitial and critical weight-normalized cumulative shock energy P^(*)_(critical)in KNN system are dis-cussed.Compared with SMP,when W_(v)/W_(p),=-3.5,in friction mode process(FMiP),KNN per-ovskite phase was formed after milling for 5 h.It implis that FMP benefit the formation of KNNperovslkite phase,The morphology of KNN powder was observed by transmsion electronmicroscopy(TEM).

Dielectric response of BaZrO_(3)/BaTiO_(3) superlattice

We use the first-principles-based molecular dynamic approach to simulate dipolar dynamics of BaZrO_(3)/BaTiO_(3)superlattice,and obtain its dielectric response.The dielectric response is decomposed into its compositional,as well as the in-plane and out-of-plane parts,which are then discussed in the context of chemical ordering of Zr/Ti ions.We reveal that,while the in-plane dielectric response of BaZrO_(3)/BaTiO_(3)superlattice also shows dispersion over probing frequency,it shall not be categorized as relaxor.

纳米结构导电聚合物及其复合材料的研究进展:制备,应用和展望（英文）

导电聚合物既具有金属材料的导电性,又具备高分子材料的特性,因此近年来得到全世界的广泛研究和应用.导电聚合物具有较宽和可调的电导率、简捷的制备工艺、可靠稳定的机械性能,以及轻质低价的优点.相比大尺度的导电聚合物,具有纳米结构的导电聚合物呈现出较高的导电性,较大的比表面积和较好的电化学活性.纳米导电聚合物和其他纳米材料结合形成的功能性纳米复合材料实现了性能的改进,在诸如电子电器、能量储存、能量收集、传感器和电磁保护防腐等各个领域有着潜在和广泛的应用前景.在这篇综述中,作者总结了近几年来(涵盖四百多篇文献)纳米结构导电聚合物及其复合材料的研究进展,讨论了纳米导电聚合物和复合材料的制备方法,列举了不同的形貌和结构及其对应的导电机理和改性方法.结合大量的实例,介绍了纳米复合材料在各领域的应用和最新动态.最后对纳米导电聚合物复合材料这一领域存在的挑战和亟待研究的热点问题进行了展望.

Shock wave compression of poled Pb_(0.99)[(Zr_(0.90)Sn_(0.10))_(0.96)Ti_(0.04)]_(0.98)Nb_(0.02)O_3 ceramics:Depoling currents in axial and normal modes

We used a 100-mm diameter gas gun to investigate the output currents due to the sudden depolarization of poled Pb 0.99 [(Zr 0.90 Sn 0.10) 0.96 Ti 0.04 ] 0.98 Nb 0.02 O 3 ceramics under shock wave compression.We conducted shock wave experiments for the normal/axial mode with the polarization vector perpendicular/antiparallel to the shock vector.The shock pressure was in the range of 0.23 to 4.50 GPa.We measured the depoling currents under short-circuit,high-impedance,and breakdown conditions.Under the short-circuit condition,the dependence of the released charge on the shock pressure demonstrates the evolution of the ferroelectric-to-antiferroelectric phase transition.The onset pressure of the phase transition is between 0.23 and 0.61 GPa,and phase transition occurs completely above 1.22 GPa.The increasing load resistance decreases the released charge and increases the released energy.The results indicate that Pb[(ZrSn)Ti]NbOceramic is a good candidate for a pulsed power generator.

THICKNESS-DEPENDENCE OF RESIDUAL STRESS IN LEAD-FREE FERROELECTRIC K_(0.5)Na_(0.5)NbO_(3) FILMS

Lead-free ferroelectric K_(0.5)Na_(0.5)NbO_(3)(KNN)films with different thicknesses were prepared by polyvinlypyrrolidone(PVP)-modified chemical solution deposition(CSD)method.Their residual stresses were studied with two methods of X-ray diffraction(XRD)and nanoindentation fracture.It was found that the tensile stress occurs in KNN films with small thickness of 1.3μm after all kinds of stresses were neutralized,which is mainly originated from the interaction across grain boundaries.With increasing the thickness to 2.5μm and above it,the residual stress changed from tensile stresses to compressive stresses,and the compressive stress decreased with the thickness increased.These results could explain why a thicker KNN film can show improved electrical properties and the larger the thickness,the better the ferroelectric and piezoelectric properties.

Structural and magnetic properties of La_(0.7)Sr_(0.3)MnO_(3) ferromagnetic thin film grown on PMN-PT by sol-gel method

We report the preparation of epitaxial La_(0.7)Sr_(0.3)MnO_(3) thin films grown on(001)-oriented 0.72Pb(Mg_(1/3)Nb_(2/3))TO_(3)-0.28PbTiO_(3) substrates by the sol–gel technique.The phase structure,magnetic properties and magnetoresistance of the samples are investigated by using high solution X-ray diffraction,atomic force microscopy,physical property measurement system,respectively.The La_(0.7)Sr_(0.3)MnO_(3) thin films display a well-defined hysteresis loop and typical ferromagnetism behavior at lower temperature.High magnetoresistance at 5 T of 42%appears at 227K for La_(0.7)Sr_(0.3)MnO_(3) thin film.

EFFECTS OF SHOCK PRESSURE AND SELF-GENERATED ELECTRIC FIELD ON SHOCK-INDUCED FERROELECTRIC TO ANTIFERROELECTRIC PHASE TRANSITION IN LEAD ZIRCONATE STANNATE TITANATE FERROELECTRIC CERAMICS

Kinetics of the ferroelectric(FE)to antiferroelectric(AFE)phase transformation under shock wave compression is critical to design the shock-activated power supply and can be characterized in terms of both a transition rate and a limiting degree of transition.By measuring the depoling currents under the short-circuit and high-impedance conditions,we investigated the influence of shock pressure and self-generated electricfield on the phase transition kinetics of tin-modified lead zirconate titanate ceramics(Pb_(0.99)Nb_(0.02)[(Zr_(0.90)Sn_(0.10))_(0.96)Ti_(0.04)]_(0.98)O_(3))in the pressure range from 0.23 to 4.50 GPa.Experimental results indicate that the shock pressure promotes the FE-to-AFE phase transition.And the self-generated electricfield does not appear to have a significant effect on the depoling currents at high shock pressures,but has a strong effect at low pressures.At 0.61 GPa and 1.03 GPa,transition rate and degree diminish with increasing the electricfield,illustrating that the self-generated electricfield suppresses the FE-to-AFE phase transition.These observations are found to be generally consistent with results under the hydrostatic compression.Fundamental issues are discussed from the perspective of the soft mode theory.