Preparation,Structure and DC Conductivity of Organic Semiconductor PANI—C4H6O6

A new organic semiconductor tartaric acid doped salt of emeraldine polyaniline(PANI-C4H6O6)has been obtained by the method of oxidative polymerization of monomeric aniline with ammonium persulfate in acidic solution.The structure was characterized by Fourier Transform Infrared technique(FTIR) and X-ray diffraction(XRD).The temperature dependence dc conductivity δdc(T)shows a semiconductor behavior and follows the quasi one dimensional variable range hopping(Q1D-VRH)model.Data on δdc(T) are also discussed.     

Optical and Electrical Properties of Sensitized Polyaniline by Electrochemical Polymerization

To sensitize polyaniline with dyes by electrochemical polymerization,HClO4 is employed as the dopant and oxidant,and the polyaniline with differnet sensitive properties is synthesized.The effect of sensitized emeraldine salt on the absorption spectrum is discussed in details.The maximum conductivity of sensitized films reaches 1.22S/cm,and investigation on dye sensitizing of the polymer reveals that C.I.Direct Blue 71,C.I.Direct Blue 84,C.I.Direct Black 19 and CuPc-(COOH)4 may enhance the photoconductivity of polyaniline greatly.     

Photoelectric Property of Polyaniline Doped with Organic Sulphonic Acid

１ＩｎｔｒｏｄｕｃｔｉｏｎＩｎｔｈｅｃｏｎｄｕｃｔｉｖｅｐｏｌｙｍｅｒ,ｐｏｌｙａｎｉｌｉｎｅｉｓｏｎｅｏｆｔｈｅｒｅｓｅａｒｃｈｉｎｇｈｏｔ－ｐｏｉｎｔｓｆｏｒｉｔｓｖａｒｉｏｕｓｓｔｒｕｃｔｕｒｅ,ｓｐｅｃｉｆｉｃｄｏｐｉｎｇｍｅｃｈａｎｉｓｍ,...     

Enhanced Efficiency and Durability of Organic Electroluminescent Devices by Doping in Emitting Layer

Remarkable improvement in efficiency and stability has been observed in a doped organic electroluminescence device, which consists of a hole-transport layer, an electron-transport layer and a luminescent layer. The hole-transport layer is a N,N'-bis(3-methyphenyl)-N,N'-diphenylbenzidine film. The doped emitting layer consists of 8-(quinolinolate)-aluminum as the host and rubrene as the emission dopant. The doped device demonstrated a brightness in excess of 40 000 cd/m 2 and the maximum external quantum efficiency of 3.4%, which is about six times and four times respectively greater than those of the undoped device. For no packaged deviced, a luminance half-life on the order of about 230 h has been achieved under a constant current density of 15 mA/cm 2, starting at 500 cd/m 2 at the room temperature.     

Efficient Organic Multi—quantum Well Electroluminescent Devices Using Aluminum as Cathodes

Organic green light emitting devices(LEDs)with multi-quantum well(MQW)structure were fabricated.Aromatic diamine(TPD)was used as holetransporting layer and potential barrier layer;Tris(8-hydroxyquinoline)aluminunum(Alq3)was acted as electron-transporting emitter and MQW green emitter.Airstable aluinum(Al)was used as electron-injection contact.The influence of the thickness of potential barrier layer and the number of quantum well on the electroluminescent(EL)efficiencies of the devices was investigated.The organic LEDs with two quantum wells showed enhanced EL efficiencies.Maximum external quantum efficiency and brightness were 1.04% and 7000cd/m^2,respectively.     

Simulation and Fabrication of Sampled FIber Bragg Grating

The calculation principle of sampled FBG,which is called transfer matrix method, is analyzed and the simulation software is designed.The sampled FBG is simulated with the software we designed and is fabricated by ourselves.The experiment result fits well with the simulated one.It is concluded that to improve the refractive modulation index is an effective way to fabricate a sampled FBG with high-reflectivity.     

Comparison of GexSi1—x Grown by UHV／CVD from Si2H6／GeH4 and SiH4／GeH4

Using double crystal X-rays diffraction (DCXRD) and atomic force microscopy (AFM), the results of Ge x Si 1- x grown by UHV/CVD from Si 2H 6 and SiH 4 are analyzed and compared. Adsorbates can migrate to the energy-favoring position due to the slow growth rate from SiH 4. In this case, a Si buffer that isolates the effect of substrate on epilayer could not be grown, which results in a pit penetrating into epilayer and buffer. The FWHM is 0.055° in DCXRD from SiH 4. The presence of diffraction fringes is an indication of an excellent crystalline quality. The roughness of the surface is improved if grown by Si 2H 6; however, the crystal quality of the Ge x Si 1- x material became worse than that from SiH 4 due to much larger growth rate from Si 2H 6. The content of Ge is obtained from DCXRD, which indicates the growth rate from Si 2H 6 is largest, then GeH 4, and that from SiH 4 is least.     

Irradiation Defects in Silicon Crystal

The application of irradiation in silicon crystal is introduced.The defects caused by irradiation are reviewed and some major ways of studying defects in irradiated silicon are summarized.Furthermore the problems in the investigation of irradiated silicon are discussed as well as its properties.     

Maximum and Continuous Wavelength Tuning Ranges of a Grating External—cavity Laser Diode

The wavelength tuning rages of a grating external-cavity laser diode(ECLD)have been studied by the equivalent avity method.The maximum tuning range(MTR)and the continuous tunding range(CTR),which are related to the maximum and the minimum threshold carrier densities,are deduced from the threshold condition.We define a ratio of the CTR to the MRT.This ratio is only determined by the reflectivities of the external and internal facets of the ECLD.The analysis shows that there is an appropriate combination of the external and internalcavity reflectivites to obtain a given CTR in the design of an ECLD.     

Photoluminescence Spectra of Disordered and Ordered Ga 0.52 In 0.48 P

Temperature-dependence and excitation-intensity-dependence of photoluminescence spectra for both disordered and ordered Ga0.52 In0.48P are measured.The disordered sample is charactierized by its single pcak photoluminescence spectrum which is excitation-intensity.independent and has different activation energy at different temperature region.The ordered sample shows double peaks,the intensity of the high-energy peak has an anomalous increase firstly and quenches afterwards.The relative henomena are reasonably explained in terms of lattice ordering and orientation superlattice model.     

Elimination of Zig—zag Defects in Surface—stabilized Ferroelectric Liquid Crystal Cells

The elimination of zig-zag defects in polyimide-coated surface-stabilized ferroelectric liquied crystal(SSFLC)cells is carried out by appliying a low-frequency electric field.It has been achieved when the thickness of SSFLC cell is 3μm.The optical spectral transmittance measurement confirmed that there is no change of layer structure,and the memory capability was not improved.The different effects of low-frequency electric field applied on the different thickness FLC cells have been observed.and experimental results were presented.     

Deposition of Silicon Nitride Films by Silane Hydrazine Process

A new catalytic chemical vapor process for depositing silicon nitride films using silane hydrazine gaseous mixture is described.This system can be useful at a temperature of lower than 400 ℃.The catalytic process gives more rapid deposition rate than 10nm/min.The atomic composition ration.N/Si,which is evaluated by Rutherfold backattering method is about 1.4under a given experimental conditions more than the stoiciometric value of 1.33 in Si3N4.The infrared transmission spectra show a large dip at 850cm^-1 due to Si-N bonds and no clear dip due to Si-O bonds.High N-H bond density is the evidence that the deposition mechanism is limited by N-N bond breaking of the hydrazine.The H contents,evaluated from Si-H and N-H bonds in the infrared absorption spectra,and the deposition rate are measured as a function of the substrate temperature.In addition some film properties such as the reistivity and the breakdown electric field are presented.     

Charged Centers in ZnS—type Thin Film Electroluminescent Devices

Charged centers exist in the phosphor layer of the common thin film electroluminescent devices.In this article,electron scattering process due to these centers is studied through phase shift analysis.The scattering rates in different cases are obtained and compared with other important scattering processes.Electron transport processed under different charged centrers conditions are simulated by means of Monte Carlo method.The quantitative results about the influence of charged centers on electron energy are obtained.     

Low Distortion 1.31μm AlGaInAs／InP MQW DFB Laser Module for CATV Systems

１ＩｎｔｒｏｄｕｃｔｉｏｎＬｏｎｇｈａｕｌｏｐｔｉｃａｌｆｉｂｅｒｃｏｍｍｕｎｉｃａｔｉｏｎ,ｍｕｌｔｉ－ｃｈａｎｎｅｌｔｒａｎｓｍｉｓｉｏｎａｎｄｏｐｔｉｃａｌｆｉｂｅｒＣＡＴＶｓｙｓｔｅｍｒｅｑｕｉｒｅ１．３１μｍａｎｄ１．５５μｍＤＦＢｌａｓｅ...     

Dynamic Single／Dual—channel Filter with Tunable Fiber Bragg Gratings

The shift mechanism of Bragg wavelength with stress variation for a fiber grating is investigated in detail.The influence of strain change on reflection and bandpass is theoretically analyzed.By applying stress, the dynamic single/dual-channel filter with tunable fiber Bragg gratings is achieved.     

Analysis of Optical Signal Transmission Characteristics in AWG Multi/Demultiplexer with Electromagnetic Field Theory

Based on the electromagnetic field theory, the optical signal transmission characteristics in input/output waveguides, slab waveguides and arrayed waveguides of the arrayed waveguide grating (AWG) multi/demultiplexer are analyzed. The relationship between the physical parameters such as geometry sizes and relative refractive index in AWG multi/demultiplexer and the optical signal transmission characteristics are discussed. This theoretical study can be used for optimizing the design and improving the performance of the AWG multi/demultiplexer.     

Carrier Transport Properties in the Doped Micro—crystalline Silicon Films

Doped micro-crystalline silicon films are deposited at temperatures as low as 400 ℃ by the catalytic chemical vapor deposition method using a silane and hydrogen gas mixture. Electrical properties such as the carrier concentration and the Hall mobility are investigated for various measuring temperatures. It is found that the grains of micro-crystalline silicon are preferentially oriented along the (220) direction , and that the Hall mobility is larger than 8 cm 2·V -1 ·s -1 , the carrier concentration is about 1×10 17 cm -1 ～1×10 19 cm -3 at room temperature.     

(Al x Ga 1- x ) y In 1- y P Films and Its Optical Constants on the Surface

１ＩｎｔｒｏｄｕｃｔｉｏｎＴｈｅｑｕａｒｔｅｒｎａｒｙｓｅｍｉｃｏｎｄｕｃｔｏｒＡｌＧａＩｎＰ,ｗｈｉｃｈａｒｅｍａｔｃｈｅｄｗｉｔｈｔｈｅＧａＡｓｌａｔｉｃｅ,ｈａｓｔｈｅｗｉｄｅｓｔｄｉｒｅｃｔｂａｎｄｇａｐ．Ｉｔｓｌｕｍｉｎｅｓｃｅｎｃｅｉｓｒ...     

Fiber Grating Ring Laser in All Optical Communication System

Erbium fiber grating ring laser(EFRL)witn an integrated travelling wave and low polarization mode noise is reported.Through modulated experiment of a successful 2.488Gb/s RZ data,it is shown that the EFRL is a promising alternative to DFB lasers for high-speed transmission applications.     

Surface Morphology and Photoluminescence of 1.3μm Wavelength In（Ga） As／GaAs Quantum Dots

Self-organized In0.5 Ga0.5As/GaAs quantum island structure emitting at 1.35 μm at room temperature has been successfully fabricated by molecular beam epitaxy(MBE) via cycled(InAs)1/(GaAs)1 monolayer deposition method.Photoluminescence(PL) measurement shows that very narrow PL linewidth of 19.2 meV at 300 K has been reached for the first time,indicating effective suppression of inhomogeneous broadening of optical emission from the In0.5Ga0.5As islands structure.Our results provide important information for optimizing the epitaxial structures of 1.3μm wavelength quantum dot （QD） devices.