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摘要：Complexes of (Dy_x,Tm_y)L₅(ClO₄)₃·3H₂O(x : y=1.000 : 0.000, 0.995 : 0.005,0.990 : 0.010,0.950 : 0.050,0.900 : 0.100,0.800 : 0.200;L=C₆H₅COCH₂SOCH₂COC₆H₅)were synthesized. The properties of the complexes were characterized with elemental analysis, infrared spectra (IR) and ultraviolet absorption spectra. The fluorescence spectra of these complexes were discussed in detail, indicating that the fluorescence intensity of Dy (Ⅲ) is enhanced by Tm (Ⅲ). This phenomenon may be due to the intra-molecular energy transfer. The complex shows the best luminescence properties when the ratio of Dy (Ⅲ) to Tm (Ⅲ) is 0.950 : 0.050. As a result, the complexes can emit white fluorescence under the ultraviolet excitation. It is predicted the complexes will become a class of luminescence materials that emit white fluorescence.  

摘要：In this work, phosphorus ion-implantation-induced intermixing of InGaAsP double quantum wells (DQWs) with different emission wavelengths was investigated by photoluminescence (PL) spectrum and cross-sectional transmission electron microscopy (TEM). After thermal annealing under specific conditions, the PL showed that the PL peaks of both wells always remain well separate under the condition of a low implanting dose (less than 7×10¹¹/cm²), the bandgap blue-shift for each well appears a maximum as the implantation doses are increased from 10¹¹to 10¹²/cm², and the blue-shift from the upper quantum well (QW) is larger than that from the lower QW under the same conditions of implantation and annealing. When the ion dose is 10¹²/cm², the PL peak of the upper QW is nearly negligible and the peaks from DQWs appear to combine together as one peak. Comparing as-grown sample with annealed sample appearing maximum blue-shift by cross-sectional TEM, the boundaries of annealed sample between wells and barriers become vague, indicating that the ion implantation results in a total intermixing of two wells.  

摘要：A scheme for probabilistic teleportation of an unknown two-particle entangled state via a four-qubit non-maximally entangled cluster state as quantum channel is proposed. In this scheme, the unknown entangled states can be teleported with a certain probability, which is determined by the smallest two of the coefficients absolute values of the cluster state. What's more, if quantum channel is maximally entangled cluster state, the probabilistic teleportation becomes usual teleportation.  

摘要：Full color display is the goal of organic light-emitting diodes (OLED), but the fabrication of stable red devices is the great barrier in the mass production of OLED.In order to use organic light-emitting diodes in displays,it is very important to obtain red light emitting with high efficiency.In this paper, a red phosphorescent material is doped into different host materials by a structure of ITO /CuPc(20 nm)/NPB(60 nm)/Zn(BTZ)₂ : Ir(DBQ)₂(acac) (80 nm)/Alq₃(70 nm)/LiF(1 nm)/Al (200 nm).It was found that the device can achieve a brightness of 25 000 cd/m², a current efficiency of 12 cd/A and the colour coordinates of (x=0.63,y=0.37). Because there is no hole blocking layer, the device producing process would be simple.  

摘要：The studies of geometrical and electronic structure of electroplex(TPD⁺PBD^-), which is formed by TPD⁺ and PBD^-, were carried out by simulation calculation. The analysis of the geometrical structure data of electroplex (TPD⁺PBD^-) suggests that the electron transfer occurs from PBD^- side to TPD⁺ side and the electroplex between TPD⁺ and PBD^- can be formed efficiently when the position of PBD^- and TPD⁺ is appropriate. The electroplex (TPD⁺PBD^-) is energetically favored comparing with isolated ions TPD⁺ or PBD^-. This result implied that the ionic state TPD⁺ and PBD^- at the interface TPD/PBD inside OLED tends to form electroplex. The lowest unoccupied molecular orbital (LUMO) of (TPD⁺PBD^-) is localized at PBD^- side and highest occupied molecular orbital (HOMO) of (TPD⁺PBD^-) is localized at TPD⁺ side. The energy gap of electroplex (TPD⁺PBD^-) is 1.3 eV, which is approximately equal to the energy difference of 1.6 eV between LUMO of PBD and HOMO of TPD. The emission of electroplex is theoretically intermolecular radiation transition from LUMO of PBD to HOMO of TPD.  

摘要：White organic light-emitting diodes (OLEDs) have been attracted much attention due to the potential applications in illumination light source and back light for liquid crystal display (LCD) as well as full color displays. A general solution to realizing white color OLEDs is to use separate multiple emitter-layers to produce different colors. The white light is achieved based to the color mixing. Unfortunately, the electroluminescent (EL) performances of this kind of devices such as color stability and efficiency still need improved. An optical microcavity has a structure with at least one space dimension on the order of optical wavelength. In a microcavity device, only one or a few optical modes are able to interact with the materials inside. Thus, the interaction between material and light within microcavity is greatly changed comparing with the condition of free space. To obtain white light in MOLED, a multimode within the emission spectrum of the wide-band emitter is essential, and can be realized by charging cavity length. However, for the white MOLED with multiple layer structure, the EL performances were seldom reported. We report the realization of a bright white MOLED with a simple two-layer structure and only one emitter layer.An microcavity organic light-emitting diode (MOLED) was developed to emit white light. The MOLED was designed and fabricated with a simple structure of glass/DBR/ITO(194 nm)/NPB(93 nm)/Alq₃(49 nm)/MgAg(150 nm). White light was observed based to the emission of two cavity modes despite only one emitter layer. By well adjusting the resonance wavelength (488 and 612 nm) and intensity, the two cavity modes give rise to a bright, white electroluminescene emission with a maximum luminance of 16 435 cd/m², maximum luminous efficiency of 11.1 cd/A. At the typical luminance of 100 cd/m², the luminous efficiency, voltage and current density are 9 cd/A, 6 V and 1.2 mA/cm² for the MOLED device,respectively. The MOLED has a CIE chromaticity coordinate of (0.32, 0.34), which is very stable under different applied voltage. The result indicated that microcavity is an efficient structure to construct white OLED.  

摘要：Rare earth tantalate is a kind of outstanding host material. Since containing elements with high atomic number, owing high density, strong X-ray absorption, high chemical stability and good radiation persistence, yttrium orthotantalate (YTaO₄ ) was considered as a promising host for both X-ray and VUV phosphors.YTaO₄ : Gd,Eu was synthesized by solid state reaction, and the conditions of reaction were studied in detail: The mixture of appropriate amounts of Y₂O₃ (99.99%), Eu₂O₃(99.99%),Gd₂O₃(99.99%),Ta₂O₅ (99.999%) and Li₂SO₄ (A.R),the Li₂SO₄ was added 1% as flux,was thoroughly ground and then move to an aluminate crucible. The furnace was heated to and kept at 1 250 ℃. The crucible was put into the furnace and fired for 4 h. The crucible was taken out directly from furnace at 1 250 ℃. After reground, the mixture was heated again at 1 250 ℃ for another 4 h. The crucible was then taken out from the furnace at 1 250 ℃. The sample of pure M'-YTaO₄ was obtained when the crucible was cooled to room temperature. The XRD result indicated that we got the pure M' type of YTaO₄ : Gd,Eu.The excitation and emissioin spectra of YTaO₄ were measured. The excitation band at 230 nm is described to a charge transfer band nature of TaO^3-₄ group. The emission band of YTaO₄ situated at 365 nm. The main emission peak of YTaO₄ : Eu³⁺ is at 611 nm and the excitation band of YTaO₄ : Eu³⁺is at about 250 nm. The excitation band at 250 nm was attributed to the result of the overlap of two charge transfer bands within Eu-O and Ta-O. This overlap makes the UV absorption of the phosphor enhanced. The quenching concentration of Y_1-xEu_xTaO₄ luminescence is at about x=0.06.For the spectra of Y_0.94-yGd_yEu_0.06TaO₄, the doping of Gd³⁺ ion into YTaO₄ : Eu³⁺ did not change the energy position of Eu³⁺ luminescence, but enhanced the emission intensity of phosphors. The best doping concentration of y is about 0.1.For the emission spectra of Y_0.94Eu_0.06TaO₄ and Y_0.84Gd_0.10Eu_0.06TaO₄ under VUV excitation, the main emission peaks of the two phosphors are the same at 612 nm. The chromaticity coordinates are x=0.652, y=0.348. The luminescent properties of the samples were studied on the VUV excitation spectra and emission spectra. It was concluded that Y_0.84Gd_0.10Eu_0.06TaO₄ gets good luminescent effect, and the energy transfer between TaO^3-₄ and Eu³⁺, Eu³⁺ and Gd³⁺ occurs.  

摘要：LiM(M=Ca,Sr,Ba)BO₃ : Dy³⁺ phosphors were synthesized by solid state reaction, and their luminescet characteristics were investigated. The emission spectra of LiM(M=Ca,Sr,Ba)BO₃ : Dy³⁺ phosphors show several bands, and the main emission peaks corresponding to Ca, Sr and Ba ion are the ⁴F_9/2→⁶H_15/2(484, 486 and 486 nm), ⁶H_13/2(577, 578 and 578 nm) and ⁶H_11/2(668, 668 and 666 nm) typical transitions of Dy³⁺. The excitation spectra for the yellow emission have the same excitation peaks located at 331, 368, 397, 433, 462 and 478 nm,corresponding to the ⁶H_15/2→⁴D_7/2, ⁶P_7/2, ⁶M_21/2, ⁴G_11/2, ⁴I_15/2 and ⁶F_9/2 transitions of Dy³⁺. The effects of doping Ce³⁺or Li⁺, Na⁺, K⁺ on the luminescence intensities of LiM(M=Ca,Sr,Ba)BO₃ : Dy³⁺ phosphors were studied, and the results showed that the intensities of LiM(M=Ca,Sr,Ba)BO₃ : Dy³⁺ phosphors are obviously effected. The intensities increase with increasing Ce³⁺ concentration and reache the maximum value at 3%. Under the condition of doping Li⁺, Na⁺ and K⁺, the intensities are enhanced, however, the charge compensation concentration corresponding to the maximum emission intensity is different with different charge compensation ions, and the optimal concentrations are 4%, 4% and 3% corresponding to Li⁺, Na⁺ and K⁺, respectively.  

摘要：A novel red light-emitting phosphors of Li₃Ba₂Ln_3-xEu_x(MoO₄)₈ were synthesized by sol-gel method. According to X-ray diffraction, the materials belongs to monoclinic system.The structure and luminescent properties of these phosphors were investigated by emission and excitation spectra in details. The main emission peak of the samples is at 616 nm. Effect of the dosage of citric acid and polyethylene glycol and the activator concentration on the crystal structure, morphology and luminescent properties were investigated by using XRD, SEM. These results showed that this phosphor can be effectively excited by ultraviolet (UV) (395 nm) and blue (465 nm) light, matching the output wavelengths of ultraviolet or blue LED chips. Integrated emission intensity of Li₃Ba₂Y_2.8Eu_0.2(MoO₄)₈ is the strongest in the series of the Li₃Ba₂Ln_3-xEu_x(MoO₄)₈(Ln=La, Gd, Y) phosphors. The Li₃Ba₂Ln_3-xEu_x(MoO₄)₈(Ln=La, Gd, Y) phosphors might be a better candidate for solid state lighting application.  

摘要：Zinc oxide (ZnO) semiconductor with a large exciton binding energy of 60 meV and a direct-band gap of 3.37 eV has attracted tremendous attention in recent years because of its high potential for applications, such as short wavelength optical devices, photonic devices and laser systems etc. Especially, the optical pro-perties of ZnO can be obviously influenced by impurity doping with different concentrations, so several techniques, such as pulsed laser deposition, reactive thermal evaporation and sol-gel process, have been employed to synthesize high quality ZnO and doped-ZnO thin films. In this work, based on the fact that metal-doped concentrations have great influence on the crystal structure and ultraviolet(UV) emission of ZnO, such as Mg-doped and Mn-doped ZnO thin films, a consistent set of epitaxial n-type conducting Zn_1-xMg_<em>xO and Zn_1-xMn_<em>xO thin films were grown by sol-gel process on Si(110) substrates, and their crystal structures and radiation qualities influenced by different doping concentrations were studied. Meanwhile, the results of XRD, atomic force microscope(AFM) and photoluminescence(PL) spectrum indicated that the crystal structure, surface morphology and UV emission are sensitive to the doping concentrations. Compared with ZnO, Zn_1-x-Mg_<em>xO and Zn_1-xMn_<em>xO thin films tends to growth in c-axis-orientation, and a strong blue-shift UV emission peak at 365 nm appears both in Zn_1-xMg_<em>xO and Zn_1-xMn_<em>xO. In particular, the visible emission of ZnO, which is typically due to the existence of surface defects and oxygen vacancies(V″ _O) defects appears between 430 and 490 nm in the PL spectra. It is passivated in Zn_1-xMn_<em>xO films at room temperature, which leads to that the UV emission qualities of Zn_1-xMn_<em>xO thin films being greater as 56 times as the visible emissions in the optimal doping concentration. At the same time, the causes of blue-shift and Zn_1-xMn_<em>xOs visible emissions passivation was studied, through the experiments it was indicated that Zn_1-xMn_<em>xOs blue-shift UV emissions could be primarily caused by the Burstein-Moss(BM) effect, and the visible emissions passivation could be caused by the reduction of V″ _O defects induced by the Mn oxide. At last, the optimal doping concentrations of Zn_0.85Mg_0.15O and Zn_0.97Mn_0.03O were demonstrated, which displays the strong blue-shift UV emissions and the best UV emission qualities.  

摘要：In this work,the InGaAsSb epilayers were grown on InP substrate, the reflection high-energy electron diffraction(RHEED) was used for in-situ monitoring InGaAsSb surface morphology. We systematically studied the effect of the growth temperature and Ⅴ/Ⅲ ratio on a serious of heteroepitaxial quality InGaAsSb films.Optimized the growth-temperature, the epilayers were performed at maintaining binary growth in the cases of 350 ℃,and the folllowing higher quality film appears at 400 ℃.The epitaxial thin films characterization were presented and analyzed, such as surface morphology, interface inspection,crystalline quality and photoluminecence characteristic by scanning electron microscopy (SEM), X-ray photoelectron spectrum (XPS),X-ray double-crystal diffraction (XRDCD) and photoluminecence (PL) etc.We also showed some questions about the growth temperature and Ⅴ/Ⅲ ratio. In conclusions, the high quality InGaAsSb epilayers with optimized growth temperature and Ⅴ/Ⅲ ratio were obtained, which exhibits a XRD peak with narrow full-width at half maximum (FWHM).  

摘要：ZnS films were prepared on glass and p-Si(100) substrates by pulse laser deposition at 200 ℃ temperature. Annealing treatment was conducted at 300,400 and 500 ℃. XRD spectra,ultraviolet-visible spectra, Alpha-step surface profiler and atomic force microscopy(AFM) was used to observe the characteristics of ZnS/glass and ZnS/Si(100).The results showed that highly oriented films are prepared with only one sharp XRD peak at 2θ=28.5°corresponding to β-ZnS (111) crystalline orientation on glass substrates. The UV-Vis absorption showed that the films deposited on glass have a good transmission over 60% in visible region. The calculation of optical band gap ranged from 3.46~3.53 eV that can be ascribed to sulphur deficiency. The images from AFM showed that annealed treatment at 500 ℃ can increase the grain size and improve the quality of ZnS films on Si(100), making the film surface become more smooth and compact than that of as-grown films at 200 ℃.  

摘要：The nanocrystal CaO : Eu³⁺ powders were prepared by co-precipitation method in this paper. Luminescent properties of CaO : Eu³⁺ with different sintering temperatures and dopant concentrations were studied. The results indicated that the samples have sharp characteristic emissions spectra of Eu³⁺. With the comparison of emission spectra of CaO : Eu³⁺ annealed at different temperatures, the integral intensity ratio of the peaks between 591 nm and 610 nm is found to decline with the temperature increasing. It was revealed that the rare earth ions (Eu³⁺) occupy different lattice position in the samples with different sintering temperatures. The change transfer state was observed between O^2- and the rare earth Eu³⁺ ion.The effect of the doped Eu³⁺ concentration on the fluorescence emission intensity was discussed, and the results showed the concentration quenching depends on the doped Eu³⁺ concentration. The optimum dopant concentration for the luminescence of Eu³⁺ is determined to be 0.4%.  

摘要：The measurements of forward current-voltage characteristic and forward capacitance-voltage characte-ristic are the most important methods to study the forward electricity characteristic of light-emitting diodes. Forward alternating current (ac) small signal method can be used to measure the capacitance-voltage characteristic of light-emitting diodes, and negative capacitance can be observed. By analyzing the responds of light-emitting diodes junction capacitance by the alternating current small signalmethod based on forward direct current, we found that the current phase of apparent capacitance is behind the phase of voltage when ＜0, leading to apparent capacitance being negative capacitance in measurement. Additionally, the expression of the negative capacitance in LED related with the recombination emitting is firstly obtained. By analyzing the responds of variable capacitance to the alternating current small signal, we also found that the variable capacitance for the specific parameter can make the phase of current be behind the phase of voltage, leading to the negative capacitance in measurement. The result of theory analysis tallies with the experiment. It was found the negative capa-citance is valuable for study the electrical characteristics of light-emitting diodes and valuable for the knowledge to improve the characteristic and parameter relevant the p-n junction internal structure of light-emitting diodes.  

摘要：Donor-acceptor (D-A) organic molecule is one of the most important conjugated organic materials, which have attracted much academic and technological research interests. In these compounds the electron-donating and electron-accepting groups are connected through a conjugated linker. Tuning different donor moiety or acceptor moiety in a D-A molecule can modify its physical and chemical properties. A novel family of α-cinnamoyl cyclic ketene dithioacetals (CCKDA) derivatives were synthesized with asymmetrical structure (D-A) in a simple and low-cost way by Claisen-Schmidt condensation reactions between the donor-containing aldehydes and the electron-withdrawing by Peng, Sun, et al. Four novel donor-acceptor molecules:(E)-1-(1,3-dithiolan-2-ylidene)-4-(10-ethyl-10H-phenothiazin-3-yl)but-3-en-2-one, (E)-4- -1-(1,3-dithiolan-2-ylidene)but-3-en-2-one, (E)-4- -1-(1,3-dithiolan-2-ylidene)but-3-en-2-one, (E)-4-(9-butyl-9H-carbazol-3-yl)-1-(1,3-dithiolan-2-ylidene)but-3-en-2-one were studied at the B3LYP/6-31G(d) level of density functional theory (DFT) and ab initio-HF. Adiabatic and vertical electron affinities, adiabatic and vertical ionizing potential were obtained. Absorption spectra were obtained by time-dependent density functional theory(TD-DFT). CIS/6-31G(d) method was used to calculate the first singlet excited state(S₁) of the four compounds and to analyze the relationship between their energies and emission spectra. The emission spectra were calculated in solvent and compared with experimental data. According to the different compounds the exchange-correlation(XC) functions were chosen properly, and the reliable emission spectra for PKD,NKD,TKD, CKD were obtained.  

摘要：In many biologies and plants,the ring containing the nitrogen atom of azepine,which as biologically active substances, is an important group of organic compounds.There is tautomers between 1H-, 2H-, 3H- in azepine, among them 2H-, 3H- system are the most important.2H-azepine is unstable index compound, through H migration, the 3H-azepine isomerization is relatively stable.The existence of four tert-butyl and PrS- ring substituent containing the 2H-azepine,it not only can migrate to hydrogen atom, but also the movement of sulfur occurred,and 3H-azepine isomerization occurs.Regarding 2,7-dimethoxy-4-methyl-2H-azepine as raw materials, through the substitution reaction with propyl thiol, 7-methoxy-4-methyl-2-propylthio-2H-azepine was synthesized and migration reaction was analyzed.IR,¹H NMR, ¹³C NMR, MS obervation showed that, at room temperature, the seletive PrS-migration base on 2H-azepine ring with 4-methyl 2H-azepine occures and 3H-arepine is established, wiche is faster than that with exitstence of tert-butyl.  

摘要：Seven complexes of rare earth (Ln=Sm,Eu,Tb,Dy)and Tb³⁺ doped with RE³⁺ (La³⁺, Gd³⁺, Y³⁺ )with phenoxyacetic acid ( HPOA ) and 1, 10-phenanthroline were synthesized. Their elemental analysis and rare earth complexometic titration were determined,the results showed that the chemical formulas were SmL₃L'·1/2H₂O,EuL₃L'·1/2H₂O,TbL₃L'· 1/2H₂O,DyL₃L'·1/2H₂O,Tb_0.5Gd_0.5L₃L'·1/2H₂O,Tb_0.5Y_0.5L₃L'·1/2H₂O,Tb_0.5La_0.5L₃L'·1/2H₂O(L=C₆H₅OCH₂COO^-, L'=phen).IR spectra, UV spectra and fluorescence spectra were studied. The results indicated that the rare earth ions are bounded with the oxygen atoms of phenoxyacetic acid and phenoxy, and with the N atoms of 1,10-phenanthroline. Fluorescence spectra of the complexes are determined at room temperature, the terbium complex showed that there is a characteristic excitation peak,which is a wide band from 280 to 380 nm, and a maximum peak at 331 nm. For europium complex, the band is from 280 to 370 nm and with a maximum peak at 348 nm.For dysprosium and samarium complexes, the bands are from 290 to 350 nm and 320 to 370 nm,the maximum peaks at 333 nm and 354 nm,respectively.The characteristic excitation peaks are assigned to the ligands metal energy transfer band. So, 331,348,333 and 354 nm were chosen as excitation wavelength to measure the fluorescence spectra of terbium,europium,dysprosium and samarium complexes,respectively. The intensity of terbium complex is the strongest, europium complex is second and samarium is the weakest.It was shown that the lowest excitation state energy level of Tb³⁺ ion matches well with the triplet state energy of the ligand phenoxyacetic acid and phenanthroline each other,the absorbing energy of the ligands may effectively transferred to Tb³⁺ion. The fluorescence intensity of terbium complex is enhanced after doping Y³⁺ ion.  

摘要：Quantum dots (QDs) samples studied in the experiment were grown by molecular-beam epitaxy on a semi-insulating GaAs substrate. They are undoping QD sample, n-doping QD sample and p-doping QD sample. The samples grown in sequence are: 400 nm GaAs layer, 100 nm Al_0.5Ga_0.5As layer, 0.36 nm GaAs layer with the Si-doping (1.5×10¹⁶ cm^-3),or Be-doping (1×10¹⁷ cm^-3), 10 nm GaAs layer, 2.35 monolayers (ML) InAs at a growth rate of 0.001 ML/s,200 nm GaAs layer. For undoping QD sample, there is a non Si or Be doped 0.36 nm GaAs layer. The sample has an ultralow density of the QDs. Therefore, we can isolate single QDs without the use of the nanoscaled masks or mesas. In the experiment the sample was cooled to 5 K and a Ti: sapphire laser operating at 750 nm is used as an excitation source. The scanning confocal microscopy with an objective (NA:0.5) is used to spatially resolve single QDs. The polarized photoluminescence (PL) and time-resolved PL measurements were carried out by time-correlated single-photon counting setup. The excitation light is a right circular polarization light. The polarization PL and time-resolved PL emissions were analyzed by a λ/4 and λ/2 wave plate and a linear polarizer to distinguish different polarization components. All the experiments were performed at low excitation power, which ensures the luminescence working in the single photon emission mode. The main conclusions were given: (1) The exciton-spin relaxation time for undoping QD sample is about 16 ns;(2) The electron spin-flip time is about 2 ns for p-doping QD sample;(3) The hole spin-flip time is about 50 ps for n-doping QD sample.  

摘要：The propagating characteristics and mode profiles of two parallel photonic crystal waveguides were studied by using finite-difference time-domain method (FDTD), and the coupling coefficient between the two parallel photonic crystal waveguides was obtained with coupled-mode theory. Numerical results demonstrated that the coupling characteristic between the two parallel photonic crystal waveguides reveals large discrimination within different frequency region. For a high frequency range of (0.32~0.44)(ωa/2πc), they exchange energy each other and optical coupling is realized, the coupling coefficient decreases with the increase of input frequency; while at a low frequency range of (0.29~0.32)(ωa/2πc), the mode profiles of the two waveguides are overlapped. Finally, A solution realizing optical beam splitter and optical power equalizer is proposed using a certain coupling length of 34a, the two incident waves with high frequencies of 0.333(ωa/2πc) and 0.357(ωa/2πc)can be split,meanwhile the wave power with arbitrary frequency at low frequency can be equalized within the two waveguides.  

摘要：By using transfer matrix, the band structures and defect mode of photonic crystals consisting of coupling single-negative materials and double-negative materials were studied. It was shown that this structure can possess a new type of photonic gap, which is invariant with scaling length. When a normal dielectric defect layer was inset, the defect mode is insensitive to the angle of incidence. However, the number of the defect modes increase with the increase of width of defect layer.  

摘要：Transmission losses are very little for optial wave in subwavelengh structure, which have wide applications in integration optics. By using two-dimensional finite difference of time domain, the coupling between two subwavelengh slits is investigated. Two slits are located on the front surface and back surface of a metal layer, displacing a certainty distance in longitudinal direction and overlap a certainty length (coupling length) in transverse direction. Optical wave transmit the metallic layer through the coupling between two slits. Varying the parameters, such as the slits length, separation distance and coupling length and so on, coupling wavelength and efficiency will change. Combining with the amplitude distributions,the optical wave forms a waveguide resonance between two slits, the resonance at the front surface couples the incident energy into the slit, but the resonance at the back surface will couple the energy away from the metal layer. The energy coupling between the two slits is achieved by a tunneling effect coupling.  

摘要：A confocal resonator is a special instance of general stable resonators. Amplitude distributions, losses and beam radii of self-reproducing modes in a confocal resonator are used to analyze general stable resonators due to their equivalence. In order to analyze a circular confocal resonator with a big Fresnel number, in this paper, we introduce a transfer matrix method to calculate and analyze the modes in a confocal resonator. It was found that the results from the transfer matrix method are in good agreement with those resulted from the integral iterative method proposed by Fox and Li and the transfer matrix method is suitable to the confocal resonator with a big Fresnel number.  

摘要：Recently, development of fabrication techniques has made possible for the dimensions of a structure to be much smaller than its characteristic lengths, such as mean free path and phase-coherence length of an electron. Such structure is referred to as mesoscopic system. The physical properties of the mesoscopic system are so affected by quantum-interference effects strongly that this system exhibits many novel phenomena. One of the intriguing phenomena is the persistent current in quantum rings threaded by magnetic flux. Prior to the experimental observation, Büttiker, Imry and Landauer suggested that the existence of persistent current is in an ordered one-dimension ring threaded by magnetic flux. Since the discovery of the persistent current, there have been many studies on the single ring, coupled ring and multiple-arm ring structures. It was shown that, in the presence of a transport current, the persistent current can flow in a ring, even in the absence of a magnetic field. The purpose of this paper is to study persistent currents in the triple-arm ring with an impurity by using quantum waveguide theory. It was found that in the presence of the transport current the persistent current arises in such structure even in the absence of magnetic field, beside, the persistent current in the triple-arm ring with an impurity and the single ring with an impurity are different, even though the ratio of the upper arm to the lower arm is same for the two cases. More importantly, It was shown that the impurity does not always suppress the amplitude of persistent current at some energy ranges.  

摘要：TiO₂ is a wide-bandgap semiconductor with wide applications range, the anatase phase TiO₂ has the better photocatalysis properties. In this paper, the optical properties of TiO₂ with the anatase structure were investigated using the full-potential linearized augmented plane-wave method (FPLAPW) in the framework of the density functional theory (DFT). We amended band gaps by using a scissor operator, so that the minimum band gap shift becomes 3.2 eV in agreement with the experiment. Optical property calculation showed that a strong optical anisotropy near the absorption edge is observed. The calculated dielectric constants at ω→0 are ε_1xy(0) (LDA) =5.52, ε_1z(0)(LDA) =5.43 and ε_1xy(0) (GGA) =5.42,ε_1z(0) (GGA) =5.26. The dielectric functions have two main peaks. One is located between 4 and 6 eV, and the other is found at 8~9 eV. As one can imagine, the two peaks are due to transition from states in the upper part of the valence bands (states) to states in the two lower Ti-3d conduction bands (π^*-d_xy, and σ^* states). In a higher energy region (>7 eV), the imaginary part of the calculated dielectric function peak positions are located at higher energies compared with experiment. Similar results were reported in calculations for the rutile structure. The disagreement of the peak positions of the dielectric functions in a higher energy region suggests that a more sophisticated method going beyond the scissors operator to describe the quasiparticle spectrum of TiO₂ is required. If we define the optical band edge as the photon energy where the value of α =10^-4 cm^-1, then the band edge E_xy(LDA)=3.52 eV, E_z (LDA)=3.93 eV and E_xy(GGA)=3.57 eV, E_z(GGA)=3.96 eV, the results are in agreement with experiment, and the generalized gradient approximation (GGA) gives no improvement in comparison with the local density approximation (LDA) by investigating the optical properties.  

摘要：Mixing small amount of the magnetic transition metal or rare earth metal ions in the non-magnetic semiconductor makes it show a certain degree of magnetism, forming the diluted magnetic semiconductors (DMS). The introduction of one of the magnetic atoms, as known magnetic impurities, into the matrix as known the non-magnetic semiconductor. In this paper based on Zener model, considering the impact of the anti-ferromagnetic exchange on the Curie temperature of DMS materials, we got the function of the doping concentration and anti-ferromagnetic exchange about Curie temperature (T_c). A detailed analysis on the Curie temperature of(GaAS ∶ TM)(TM=Sc,Ti,V,Cr,Mn,Fe,Co,Ni) was carried out. A conclusion was drawn from the analysis. It follows: when x＜x₀,T_c increases with x; when x=x₀, T_c reaches maxima; when x＞x₀, T_c always decreases with x increa-sing. At the same time the critical doping concentration x₀ decreases gradually with y, and Curie temperature T_c always is lower.For n-type doping cases, T_c is no longers a monotone function for the x, there is a maximum value only, however, for the p-type doping T_c displays a monotonous increase.  

摘要：By using direct current (DC) magnetron sputtering method, silver films were deposited on large area plane glasses, which were pre-deposited with Al₂O₃ films with thickness of 25 nm. The relationships between sputtering power and deposited rate, surface microstructure and electric resistivity of silver films were studied. When sputtering power is lower than 2.8 kW, the deposited rate increases steadily with sputtering power, and homogeneous silver films with decreasing electric resistivity were obtained. However, silver films with abnormally large grains and increasing electric resistivity were fabricated when sputtering power is more than 2.8 kW. Silver film with the best microstructure and the lowest electric resistivity is obtained at the sputtering power of 2.8 kW.  

摘要：Indium tin oxide (ITO, or tin-doped indium oxide) is a mixture of indium oxide(In₂O₃) and tin oxide (SnO₂), typically 90%In₂O₃, 10%SnO₂ in mass fraction. It is transparent and colorless for ITO layers. Indium tin oxides main feature is the combination of electrical conductivity and optical transparency. ITO is mainly used to make transparent conductive coatings for flat panel displays, plasma displays, and solar cells. In this paper, ITO thin films were grown on c-face sapphire substrate by rf magnetron sputtering from an oxide ceramic target of 90% In₂O₃ and 10%SnO₂. The sapphire substrate were cleaned strickly and blown dry in N₂ gas before they were introduced into the chamber. High purity Ar and O₂ were introduced through independent mass flow controllers after the vacuum chamber was evacuated below 11×10^-5 Pa. The oxygen content in the sputter gas was determined by the oxygen-to-argon partial pressure ratio. The process total pressure was kept at 0.5 Pa and the sputtering time was varied to obtain thin films with thickness ranging from 0.2 to 0.8 μm. The structural, optical and electrical properties of the film were specially studied. According to the XRD diffraction measurement, it was found that ITO thin films grown on sapphire substrate show highly (222)-preferred orientation. With the increase of the films thickness, the 2θ angle of (222) diffraction peak moves toward to larger direction and the full width at the half maximum (FWHM) of the peak decreases. When the thickness of the ITO thin film is 0.2 μm, the FWHM is about 0.46°. When the thickness increased from 0.4 μm to 0.8 μm, the FWHM decreased from 0.45° to 0.43°. The thickness of the thin film also effected on the average grain size, the average grain size is 17.8,18.3,18.7 and 19.3 nm for ITO thin film with a thickness of 0.2, 0.4, 0.6 and 0.8 μm, respectively. According to the optical measurement results, the optical transmittance of the film decrease with the increase of the films thickness. The transmittance is about 80% and the 60% for the thickness of 0.2 μm and 0.8 μm. The electrical measurement on the films showed that the resistivity decreases with the increase of the films thickness. The resistivity is 9×10^-4Ω·cm for ITO film with the thickness of 0.2 μm. When the thickness is increased to 0.8 μm, the resistivity is decreased to 5.5×10^{- 4} Ω·cm. Thus, in factual applications, one must choose an ideal thickness of the ITO thin films in order to achieve a satisfactorily structural, optical and electrical property.  

摘要：Well-aligned ZnO nanonails were synthesized on Au coated Si(100) substrates via chemical vapor deposition(CVD) method at 550 ℃. The presence of only (002) diffraction peak and its corresponding FWHM of 0.166° in the XRD patterns indicated that the ZnO nanonails exhibited (002) preferred orientation and good crystal quality. HRTEM and SAED results showed that the ZnO nanonails are single-crystal. Growth mechanism of the ZnO nanonails was also presented. The results showed that due to the large lattice mismatch between ZnO and Si, ZnO_x buffer layer is firstly deposited on Si substrate, and then ZnO nanonails are grown perpendicularly on the substrate by VLS mechanism.