最新刊期
卷 11 ， 期 4 ， 1990
- 摘要：ZnSe films have been widely studied in recent years because of its potential applications as efficient blue luminescence and laser material. In this paper we present the growth and lasing characteristic of ZnSe films grown by organometallic vapor phase epitaxy (OMVPE).The dimethyl zinc (DMZn) and hydrogen selenide (H2Se) were used as zinc and selenium sources and palladium diffusion hydrogen as carrier gas. ZnSe heteroepitaxial growth was performed in a horizontal radiant -heated reactor under atmospheric pressure on GaAs (100) substrate. PL was measured at 10K under 365 nm line of a mercury arc lamp by the MM-12 monocbromator with S-1 photomultiplier.Stimulation and lasing were measured by a 44W grating monochromator with C31034 photomultiplier at 77K under 377nm line of a N2 laser with power density of 3MW/cm2.110|60|1更新时间：2020-08-11
- 摘要：The influence of forming voltage on the ACEL characteristics of ZnS:Mn, Cu powder DCEL devices is investigated.The samples of DCEL device were formed under 100, 115, 130, 145 and 160 volts respectively, and then operated under AC voltage of 50Hz. The operation voltage was risen from 55 to no volts step by step, At each step, the samples were excited simultaneously in the same period for several hundred hours. In the meantime the brightness and current were recorded.The results from experiments are analyzed and the influence of forming voltage on the two most important parameters, that is the initial and the final brightness at different operating voltage is studied.The experimental results show that the order of arrangement of the initial and the final brightness from lower to higher changes regularly with the increased forming voltage and operating voltage. At the lower operating voltage, the lower the forming voltage, the higher the brightness is. With increasing operation voltage, the order of arrangement of the initial and the final brightness is regularly reversed gradually.An interesting and important property is discovecl. This property shows that the state tends to, be identical with increasing AC operation voltage for DCEL samples formed under various DC voltage. It also means that the higher the AC operation voltage,the less the influence of forming voltage on ACEL characteristics of DCEL devices is. For this reason, the difference in ACEL for samples formed under different voltage decreases with the increase of operation voltage and at last the ACEL characteristics tend to be the same. The phenomenon is considered that Cu+ migration happens under AC operation, which is just like that under DC operation.103|42|3更新时间：2020-08-11
- 摘要：Some papers have been published on luminescence of free exciton under high density excitation in CdS. But most of the research about exciton-exciton interaction are concentrated on photoluminescence below 77K. So far no report is found on free exciton emission in forward biased CdS MIS diodes with high pulse current density.Undoped CdS crystals were grown by sublimation in our labora tory.Dice with dimensions of 5×2×1mm3 were annealed in molten cadmium at 650℃ to reduce their resistivity to the range of 0.1-5Ω·cm. The MIS structure was prepared by making an ohmic contact on the substrate and evaporating an insulating layer and Au contact on the opposite surface. PL and EL were excited by 3371Å line of a pulsed nitrogen laser or by the pulse with high current density.105|79|0更新时间：2020-08-11
- 摘要：Some features of exciton energy transfer mechanism to luminescence centers were discovered in a-type Zn-orthosilicate excited by optical energies approaching the threshold of fundamental absorption (Eg=5.5eV). The activation energy of exciton diffusion in one of the relaxed states was estimated as 0,075eV and the diffusion volume, passed by an exciton till autolocalization as 0.5×10-19cm3. Experimentally determined parameters of energy transfer in phosphor matrix serve the practical aim of selection the optimum particle size distribution.96|74|1更新时间：2020-08-11
- 摘要：Recent demonstration of the wavelength tunable Ti3+:Al2O3 laser has led to increased interest in the growth and spectroscopic characters of Ti3+ Al2O3 crystal. The characteristics of crystal depend on the growth method. Two key properties of these crystals are the concentration and optical absorption cross section of the Ti3+ ions. The single crystal having high concentration of Ti3+(0.3 wt%)and good optical quality,was grown with IFUS method(Induction Field Up-Shift Method). The absorption, polarized fluorescence spectra and lifetime were masured at 300K.Analysis of the fluorescence spectra of Ti3+ ions in Al2O3 is made for the temperature ranged for 15K to 290K.The temperature dependence of fluorescence spectra of Ti3+-doped sappire is shown in Fig.6.123|67|1更新时间：2020-08-11
- 摘要：Trivalent gadolinium is an important activator and sensitizer.In the present paper, the investigation at room temperature on spectra of Gd3+ ion and energy transfer between Gd3+ and Tb3+ in the systems of BaMgF4:Gd3+ and BaMgF4:Gd3+ Tb3+ are reported. Samples studied were prepared by a solid-state at high temperature from BaF2,MgF2,GdF3 and TbF3 under a flow of hydrogen-nitrogen mixture.109|38|6更新时间：2020-08-11
- 摘要：LaOX:Ho3+ phosphors (X-=Cl-,Br-) were synthesized and their fluorescence spectra at room temperature and liquid nitrogen temperature were measured. Based on the Double Sphere Coordination Point Charg eField (DSCPCF) model, the coordination field perturbation energy levels of Ho3+ ions doped in LaOX matrixes were calculated and the corresponding spectra assigned. The energy levels calculated agree well with the spectra observed. And the theoretical assignments bring out a resonable explanation for the "Saddle-shaped" excitation band of 5I8-5G6 hypersensitive transition and the temperature effect on 5I8-5G6 and (5S2,5F4)-5I8 transition bands. By comparison with Point Charge Field (PCF) model, DSCPCF model makes Bm2 decrease slightly, while Bm4 and especially Bm6 increase greatly. It is this correction that overcomes the shortcoming of PCF model in certain degree.117|159|2更新时间：2020-08-11
- 摘要：ZnSe-ZnS strained-layer superlattice was thought to be an important optoelectronic material of blue region,It is very difficult for us to obtain p-type ZnSe semiconductor.Some scientists have manufactured the p-type ZnSe materials.(see Table 1) so far.Using the Van De Pauw-Hall measurement with different temperature.we verified that the ZnSe-ZnS SLS(No.87039, undoping) grown by atmospheric pressure MOCVD was a p-type semiconductor material. The electrical parameters are shown in Table 2.114|78|0更新时间：2020-08-11
- 摘要：In this paper, a multifunctional laser-induced time-resolved fluorimeter is described. Basic components of the device are: anactive Q-switched Nd:YAG pumped dye laser(YG581/TDL50) as the excitation light source, a gated vidicon optical multichannel analyzer(WPl/WP2) as the fluorescence detecting equipment, and a electric trigger which made by our laboratory as the external trigger source. The applied software and interface between IBM PC/XT computer and the fluorimeter are designed for data acquisition and data processing of fluorescent spectra.Using the output of frequency tripling of Nd:YAG laser(355nm),the DBM(dibenzoylmethane) produces very much weaker luminescence in 430-510nm, whereas TOPO(tri-n-octylphosphine oxide) has much stronger luminescence in 365-430nm. The data of luminescence lifetime demonstrate that the luminescence of DBM and of TOPO are phosphorescence and fluorescence, respectively. However, the fluorescence emission of TOPO decreased remarkably in the presence of DBM. The sharp line emission of RE-DBM-TOPO systems is observed, Eu-DBM-TOPO and Sm-DBM-TOPO show very intense emission, whereas Tb-DBM-TOPO shows very weak emission in high concentration. The fluorescence emissions of RE-DBM are very much weaker than those of RE-DBM-TOPO, but the characteristic emissions aren't observed in RE-TOPO. The fluorescence lifetimes of Eu-DBM, Eu-DBM-TOPO, Sm-DBM and Sm-DBM-TOPO are measured to be 100, 500, 32 and 45us at room temperature using this device, respectively. The fluorescence lifetmes are similar for the different characteristic emission of each chelate. The fluorescence decay curves show exponential decay process for fluorescenc emission of RE-DBM and nonexponential decay process for fluorescence emission of RE-DBM-TOPO.129|67|0更新时间：2020-08-11
- 摘要：As a promising phosphor for fluorescent lamp,Ce-Mn activated fluo-rinphosphate(FAP:Ce,Mn) has been studied in these years. The lumen efficiency of this phosphor is very high, but one drawbacks of it is its low lumen maintenance in lamp. The depreciation rate of. FAP:Ce, Mn in lamp is about twice as much as that of Halophosphor ((F,Cl) AP:Sb, Mn). To improve the application of this phosphor, it is essential to study the depreciation properties of FAPCCe, Mn.In this paper, the depreciation of FAP:Ce, Mn both in lamp and under the UV radiation of (185+254) nm is reported, the key factors which affect phosphor depreciation are analyzed and possible mechanism of its depreciation is conjectured.The samples were prepared from solid state reaction. The 40W fluorescent lamps were made with ordinary technique and its lumen output in different operating time was measured. A 25W low pressure Hg discharge lamp was used as the source of UV radiation. Efficiency of samples in different radiation time was measured and the diffuse reflection spectra of samples were measured as well.Depreciation curves of lumen efficiency of FAP:Ce, Mn and (F,Cl) AP:Sb, Mn in fluorescenct lamps are shown in Fig.1. It can be seen that the depreciation processes of the two phosphors are very similar, but the depreciation rate of FAP:Ce, Mn is about twice as much as that of (F, Cl)AP:Sb, Mn.Depreciation curves of efficiency of FAP:Ce, Mn and (F,Cl)AP:Sb, Mn under UV radiation of 254nm are shown in Fig.2.It shows that the depreciation rate of FAP:Ce, Mn is about 3 times as much as that of (F,Cl)AP:Sb, Mn. Two main factors affect the depreciation properties of FAP:Ce, Mn particularly. Ce concentration and the atmosphere in which the sample isprepared,Fig. 3 and 4 show the effect of Ce concentration on the depreciation rate, and the absorption properties of the phosphor. The depreciation rate of FAP:Ce, Mn is almost directly proportional to the Ce concentration. And when Ce exists,the absorption of the sample in some wavelength areas markedly increases after UV radiation. Fig. 5 and Table 1 show the relationship between the forming atmosphere and depreciation of FAP:Ce, Mn.The sample prepared in reductive atmosphere is apt to depreciate and shows more intensive absorption in some areas after UV radiation than that made in air.According to the analysis by comparing the depreciation action between FAP:Ce, Mn and(F, Cl)AP.Sb, Mn both in lamp and under UV radiation, it can be concluded that the depriciation of the two phosphors belongs to the same, sort, caused by the formation of colour center in phosphor crystal by UV radiation.119|47|1更新时间：2020-08-11
- 摘要：In this paper, we report the manufacture and characteristics of buried twin-ridge substrate large optical cavity structure GaAIAs/GaAs laser (BTRS-LOC). This laser has following features.(1) Thethinner active layer(~0.1μm) can be grown by Using LPE on the twin-ridge substrate. The optical power confinement factor will become smaller, so the large spot size of near-field pattern at facets can be obtained. (2) The spot size of the near-field pattern is further enlarged by the LOC structure. (3) The current confinement to the stripe is realized by a reverse-biased heterojunction of n-GaAs (current blocking layer) and p-GaAlAs (first cladding layer). (4) The transverse mode is confined by the built-in refractive index difference which is caused by the fact that outside the channeled region, the evanescent tails of lasing light reach the current blocking layer.119|93|0更新时间：2020-08-11
- 摘要：Visible light-emitting diodes either with a structure of glass/ITO/p a-SiC:H/i a-SiC:H/n a-SiC:H/Al or with a structure of glass/ITO/a-SiC:H/Al have been developed by the glow discharge deposition in SiH4+CH4 mixture. The p-i-n LEDs exhibit characteristics of switching diode with turn-on voltage of about 16V, while the another type of LED exhibits characteristics of avalanche breakdoswn in a uniform medium with threshold field of about 1.5×108V/cm. The two types of aSiC:H thin film LEDs named injection LED and impact ionization LED, respectively, emit visible white light when their own critical conditions are established. Both of them have a broad lightemission band centred around 2.0eV and extend over the whole visible range. The peak energy of injection LED's spectrum does not change as the injection current increases, but the peak energy of the impact ionization LED's spectrum changes from 1.87 eV to 2.04 eV when the avalanche current increases from 0.15mA to 6mA. The optical gap of a-SiC:H thin films,including either n-or p-doped layers, is maintained at 2.2 eV by adjustments of the deposition parameters and measured according to Tauc plot. The irradiation recombination mechanizm concerned with these LEDs is suggested to be a transition between the extended states in conduction-band and the localized states in valence-band tail.The variation of peak energy of the impact ionization LED's spectrum is attibuted to the energy distribution of excess electrons in conduction-band, which is dependent on the excitation voltage.96|54|0更新时间：2020-08-11
- 摘要：We have investigated the properties of electron paramagnetic resonance(EPR) spectra and de electrical conductivity (σdc) from undoped and iodine-doped PPP prepared by Kovacic method. The experimental results of σdc and EPR in iodine-doped PPP are presented here. It is found that a novel phenomenon occurs for EPR signals with the change of iodine concentration [N(I)] in doped PPP. According to our experimental results, it is suggested that polarons and bipolarons should change into each other in the iodine-doped PPP.98|35|1更新时间：2020-08-11
- 摘要：The present paper reports a novel chemiluminescence (CL) system, iso-propylalcohol-ClO--H2O2. In basic medium, iso-propylalcohol can react with ClO- or H2O2 to produce CL emission. If iso-propylalcohol was initially mixed with ClO- and then H2O2 was added to the above mixed solution the CL intensity became greater. The kinetic process agreed with the index attenuation formula I(t)=16exp(-0.21t), and the constant of attenuation speed was 0.21sec-1. The effects of reagent concentration, some metal ions and pH value of ClO- solution on the CL in tensity were studied. Acetaldehyde can enhance the CL intensity, and the enhanced CL intensity is proportional to the concentration of acetal-dehyed within the range of 5.0×10-10g/ml-1.0×10-6g/ml. Based on this result, we have developed a new CL method for the determination of trace acetaldehyde, with which some foreign inorganic ions as well as usual organic compounds do not interfere. The mechanism of the CL reaction has also been briefly discussed.109|42|1更新时间：2020-08-11
- Address：No.3888 Dong Nanhu Road, Changchun, Jilin, China Postal code：130033
- Tel：0431-86176862 Email：fgxbt@126.com
- Technical support is provided by Beijing Founder electronics co., LTD 吉ICP备11002662号-17
京公网安备11010802024621 - It is recommended to read the content of this site in Chrome&IE9+. Please switch to extreme mode in browser 360.
- Cookies We use cookies to help provide and enhance our service and tailor content. By continuing, you agree to the use of cookies.
0