最新刊期
卷 8 ， 期 3 ， 1987
- 摘要：The Tb3+ ion can emit the green fluorescence, it is interesting one of elements for luminescent material. The fluorescence of Tb3+ originates from the transitions between 5D3 and 5D4 energy levels, the fluorescent range are about 380-680nm, the transition of 5D4-7F5 of Tb3+ ion is the strongest at 542nm, which can be considered as a standard wavelength of green color in luminescence. The blue light comes from 5D3 energy level, which influences the purity of light color, therefore, it is necessary to improve the fluorescent color.As known, it is possible to increase the concentration of Tb3+ for improving ligth color, because there are the cross relaxation between 5D3-5D4 and 7F6-7F0 energy level pairs. However, it is hard to get high concentration of Tb3+ in the luminescent material, so there are stronger blue color in the fluorescence of Tb3+. We have tried to improve light color in pan-taphosphate and found a new quenching element Tm3+ to the fluorescence of 5D3 energy level of Tb3+, the quenching machanism is considered to be cross relaxation process between energy level pair 5D3-5D4 of Tb3+ ion and energy level pair 3H6-3F4 of Tm3+ ion. In this paper, the fluorescent spectra of erystals were measured for variant concentration and used to calculate the cross relaxation probability and the dependence between fluorescent intensities and the concentrations of Tm3+ and Tb3+ ions. We compared these fluorescent intensities with the fluorescence of pure Tb3+ in crystals.98|29|0更新时间：2020-08-11
- 摘要：It is well known that if donor-donor transfer can be omitted, the energy transfer between donors and acceptors can be described by static model[1,2]. In this case the decay of the donor fluorescence can be expressed by F(t)=exp(-γt)f(t)=exp(-γt)exp[ΣIn(1-CA+CA exp(-X0t))],(2) where γ is the intrinsic decay rate of the donor, CA is the concetration of the acceptor, X0n is the transfer rate between the donor at the origin and the acceptor at the site n, the summation is taken over all cells. With the approximation of isotropic contineous medium and CA <<1, it was shown[1,2,3] for electric multipole interaction lnf(t)=-CA (X0t)3/sΓ(1-3/s), (4) where X0 is the D-A transfer rate at the separation R0, the radius of the Wigner-Seitz sphere. This expression is valid if X0t>>1.If CA <<1 is invalid, more terms should be taken in the expansion of (2). It is shown in this paper, that (4) must be modified by lnf(t)=-1n(l-CA)-A(CA)CA (X0t)3/sΓ(l-3/s), (7).108|39|0更新时间：2020-08-11
- 摘要：We have investigated the excitation and recombination machanism of Mn and Cu centers for two kinds of EL panels:alternating current <ZnS:Mn, Cu) and direct current. By measuring the emission spectra, time-resolved emission spectra, current waveform, luminescence brightness waveform, luminescence decay and the relationship between luminescence intensity and Mn or Cu concentration, etc. Both ZnS:Mn,Cu and ZnS:Mn,Cu(Cu) were made from the same powder phosphor. But the latter one was treated with copper coating procedure. Mn ion concentration, from 3×10-5 to 2×10-2, Cu concentration:from 2×10-4 to 2×10-2mol.97|66|0更新时间：2020-08-11
- 摘要：In this paper, the spectral properties of Ho3+ ions in ZnS have been investigated systematically. By means of emission spectra excited by different wavelength [Fig.2-3],excitation spectra [Fig.4],fluorescent decay and temperature dependence of emission intensities, we have got the following results. 1)Transitions between 29000cm-1-14000cm-1 have been identified. Emis-sion-from the excited states 5G5,5G4, 5G5, 5G6, 3K8, 5F2, 5F3, 5S2 and excitation to the states 5G6, 5G5, 3K7, 3H6, 5G3(3L9) have been observed [Fig. 5].105|45|0更新时间：2020-08-11
- 摘要：Increasing attention has been recently paid to the deep centers in Ⅲ-Ⅴ semiconductor alloys since the main electronic properties of these materials vary continuously with their compositions and a large range of compositions can be selected for optimizing their applications such as for luminescence, laser and microelectronic devices. On the other hand, research on the dependence of deep center characteristics on alloy compositions can offer the possibilities to gain the important information about the centers from the point of view of defect physics.In this paper we report the measurement results for the nonexponential thermal transient capacitance and DLTS spectra in Fe-doped GaAsP alloy for large range of compositions.Samples used in this study were p+ n diode, n-type, GaAsP layers were grown on substrates of GaAs(for x<0.5) and GaP(for x>0.5) using MOVPE. The p+ layers were obtained by Zn diffusion, iron impurities were also diffused into samples and their concentrations were selected in the range of NFe/ND~0.05. The composition x of each samples studied was measured by microprobe analysis in a scanning electron microscope with uncertainty less than ±2%.82|36|0更新时间：2020-08-11
- 摘要：We have studied the emission spectrum of CdS single crystal in the excitation range from 106 to 107W/cm2 at temperature 4.2K.When the excitation density is low (106 W/cm2), the emission spectrum is characterized by two peaks 4869Å (named I2) and 4888Å (named I1) which are the luminescence lines of neutral-donor-bound eXciton and of neutral-acceptor-bound exciton. As the excitation density goes up, the intensity of I2-peak decreases relatively and a luminescence band structure appears in the red side of I1-peak. When the excitation density up to 1.7×107W/cm2, a new peak (named U) is found. The new peak is characterized by narrow line width (about 3Å half width) and great luminescence intensity (Fig.1)We studied the polarization of I1-peak, I2-peak and U-peak as the excitation density changed. We found that the polarization v.s. excitation density for I1 and U is the same. And we also studied the U-peak luminescence intensity by changing temperature in a fixed excitation. And the result is the same with that of I2-peak.Finally we concluded that the U-peak is the inelastic scattering luminescence of neutral-donor-bound exciton.We also caculated the intensity and energy of U-peak theoretically, the results are in correspondence with experimental results.We suggested the model of luminescence of inelastic bound exciton-exciton scattering.The causation and features of the peak were clearly explained using the model.119|62|0更新时间：2020-08-11
- 摘要：Typical DAP (donor acceptor pair) recombination behaviours were found for the 1.18eV emission in InP and reported in this paper. The evidences for that the 1.18eV emission band in InP is associated with Mn impurity centers in InP has been published before. No evidence for the DAP nature of this band has been reported previously although DAP recombination as one of possible transition mechanisms was suggested before. The shape line structure of DAP emission has not been reported to be clearly identified in Ⅲ-Ⅴ semiconductor compounds with direct energy gap. In this kind of materials the DAP nature can be established by observing the time-resolved spectra and the intensity-dependent peak shift of the luminescence. The methode of frequency response spectroscopy (FRS) and luminescence decay measurement using boxcar were used in the present work and the emission peaks of this band corresponding long live emission shifting to low energy side as an evidence for the DAP nature was obtained in all the samples measured. The excitation intensity dependent peak shift about 1.8meV was also observed in these samples. The results provides convincing evidence that 1.18eV emission in InP is from DAP recombination. The neutral state of Mn ions in Ⅲ-Ⅴ compounds is Mn3+ with configuration d4 but the half filled shall configuration d5 is strongly favoured on the ground of energy stability. The ODMR and EPR investigation, which was published previously, also suggested that the transition of 1.18eV band be related to Mn2+ ion. This implies that the DAP transition of 1.18eV can be expressed as [Mn2+]h + D°→[Mn2+]+D+ + hv1·18eV. where D represents inadvertent donors in InP and [Mn2+]h means that a hole is loosely bound to half shall state Mn2+. [Mn2+] h keeps electrically neutral.117|60|0更新时间：2020-08-11
- 摘要：An empirical estimation for the composition of GalnAsSb with the lattice matched to InP is introduced, which is based on the electronegativity difference of the constituent elements and the lattice constants of binary compounds. The results are in aggrement with those obtained by the following equation: a(Å)=6.0584-0.4165x+0.4204y+0.0317xy. Layers of GalnAsSb, for the first time, are achieved both on (100) and (111) B InP by LPE. The dependence of the surface morphology and hetero-interface quality on growth conditions is investigated. The solid compositions are varied from 0.46 to 0.51 for x and 0.02 to 0.045 for y, which is over the miscibility gap for the GalnAsSb reported respectively by K. Nakajima et al. The wavelength of the main luminescence peak can be shifted from 1340nm to 1630nm (Fig.4).In Fig.5, are shown the X-ray diffraction peaks of typical GaInAsSb/InP heterostructure. The FWHM for the epilayer is 12s, indicating the high layer quality.The electrical properties are taken from Van der Pauw measurements. Carrier concentration in the range of 1015cm-3 and room temperature electron mobility up to 12210cm2/V·s, which are the highest data so far for the Ⅲ-Ⅴ quaternary alloys, have been achieved.101|79|0更新时间：2020-08-11
- 摘要：The characteristics of ZnS:Mn powder phosphors fired in HC1 atmosphere are systematically described.This technology is with lower sintering temperature and shorter firing period because of the strong mineralization of HC1 gas. Thus, the phosphors obtained not only crystallize well, but also have smaller particle size. The brightness of the phosphors under UV and DC excitation is higher than that of phosphors produced in conventional way.In HC1 atmosphere, the recrystallization of the material is very rapid. The process can be finished in 10 min. The content ratio of hexagonal to cubic phase formed in sintering temperature is hardly shifted by slow cooling or annealing. This may be the effect of C1 induced by HC1 atmosphere. The experiment also suggests that ZnS raw material play an important role in forming crystalphase.In order to know the effect of different content ratio of crystalphase on DCEL, some ZnS:Mn samples with variable hexagonal phase composition were coated with copper and then aged under electric field. It is observed that the samples containing less hexagonal phase are better in maintenance. Thus, it may be concluded that the DCEL lifetime can be improved by appropriately reducing hexagonal phase content.In view of the symmetry of crystal field, hexagonal or cubic phase may affect the splitting of the activator’s energy level. Therefore, the brightness and the location of spectrum peak, but in spite of maintenance, can be influenced. So, the distinction of the lifetime should not be caused by different crystalphase. According to the model of Cu+ migration, it is considered that the problem of maintenance is associated with the property of CuxS phase. Hexagonal and cubic phase posses different crystal lattice, and their ratio determines the structure of CuxS which grows on those lattice. This has been identified from experimental data. The copper-coated ZnS raw material with cubic lattice shows high resistivity. And ZnS: Mn fired in lower temperature also has low conductivity because it contains more cubic phase composition on that preparing condition. However, the resistivity is usually lower for the material containing more hexagonal phase content. Generally, the maintenance characteristic is better for the sample with higher resistivity and is worse for that with lower one. So, the stability of CuxS phase is affected by the hexagonal phase content and that leads to different DCEL lifetime.This experiment suggests that the DCEL phosphors with higher brightness and longer lifetime are possible to be prepared by the sintering technology using HC1 atmosphere.106|46|0更新时间：2020-08-11
- 摘要：The characteristics of ACEL in ZnS:Er3+ thin films grown by ALE method were reported for the first time. Especially, at high Er3+ concentration, red emission spectral line corresponding to the transition from 4F9/2 to 4I15/2 was strongly increased. The cross-relaxation process between Er ions was proposed for the interpretation of the experimental results.The EL device is glass-SnO2-Y2O3-ZnS:Er3+-Y2O3-Al sandwich structure.The Y2O3 insulator layer was made by electro-beam evaporation.ZnS:Er3+ active layer was grown by ALE method. The thicknesses of Y2O3 layer and ZnS:Er3+ active layer were about 300nm and 400nm, respectively. The concentrations of Er3+ in ZnS ranging from 0.05% to 12%(wt).108|48|0更新时间：2020-08-11
- 摘要：In this paper, We studied the behaviors of the Be-doped p-GaAs grown by a home-made MBE system with low temperature photoluminescence.The free exciton emission and the bound excitons emission associated with neutral acceptor, ioned and neutral donors were observed at 4.2K temperature. In the lightly Be-doped GaAs eight bound exciton lines (d, x)associated with the Ga vacancy were observed between 1.503-1.515eV. It was belived they are related to our growth condition of samples: substracte temperature was about 600℃ and As4 was taken as As source.97|96|0更新时间：2020-08-11
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SPECTRAL STRUCTURE AND VALENCE STABILITY OF EUROPIUM (Ⅱ) IN SYSTEMS ARF4 (A=Na, K; R=La,Gd,Lu and Y)
摘要：A study was made on the spectral structure characterization and valence stability of Eu2+ ions in ARF4 (A=Na, K; R=La,Gd,Lu and Y), one of complex fluorides useful as multifunctional materials.Alkali metal ions have the lowest ionizing potential and highest positive electricity and stronger ionic bond is formed easily in its compounds.The Eu2+ ion probably is given priority to occupy a alkali ionic lattice site in the complex fluorides synthesized by alkali and rare earth fluorides because the alkali ions have smaller electronegative and longer ionic radius than Eu2+ ion.Systemic compounds of this complex fluorides were synthesized with successive firing in a stream of high purity argon (0.51/min) in the temperature range of 550-800C. However, compounds of systems AF-Rf3 (A=Rb, Cs;R=La,Gd,Lu and Y) were not obtained.A sharp peak at 360 nm was observed in the fluorescence emission structure of Eu2+-doped ARF4, when R=Gd,Lu or Y at 300K, or R=La at 77K. The emission arises from 4f7 (6P7/2)-4f7 (8S7/2) transition of Eu2+ ions. In addition to sharp peak emission, broad band was observed at 396nm. In concordance with criterion of electronic transition of Eu2+ ion in complex fluorides, both d-f and f-f transitions could be observed, with the energy difference between absorption bottom of 4f-5d and centre of gravity for 6P7/2 being smaller than 300cm-1. No sharp peak emission of Eu2+ ion was observed in systems AR’F4 (A=Na, K; R'=Lanthanoid ions except La, Gd and Lu).The data on ESCA and magnetic susceptibility show that divalence europium is stable in ARF4:Eu2+ synthesized in the stream of high purity argon.108|23|0更新时间：2020-08-11 - 摘要：There have probably been more spectrascopic investigations involving Eu3+ reported in the last few years than those of any other Ianthanide.This reflects, of course, the importance of Eu3+-activated phosphors and the interest in Eu3+-based lasers. The volume of work is more remarkable when one realizes that practically all of these investigations are concerned with transitions or fluorescence from several 5D level in the visible region of spectra.This paper reports some results of such an investigation. The growth of GdP5O14(GdPP):Eu3+ single crystals was studied by hydrothermal method.The excitation, emission,absorption and infrared spectra of the crystals wers measured at room temperature and analyzed. Most of the observed emissions and absorptions can be uniquely assigned in terms of specific transition between levels in the 4f shell of Eu3+ ions, and conversely most of predicted transition were obverved.The symmetry-determined electric and magnetic dipole selection rules for the C2, site symmetry are quite well for Eu3+ ions to obey. The strongest absorption at 394nm and the weak sharp band at 361nm could immediately be assigned to transition from 7F0 to 5L6 and 5D4, respectively. The 7F0-5D3 transition was placed at 4l3nm.The bands at 462nm and 522nm identified by their close correlation with transition observed for Eu3+ in the GdPP:Eu crystals are assigned for 7F0-5D2 and 5D1 as has been shown experimentally that the intensity of band at 522nm (7F0-5D1) arises entirely via the magnetic dipole mechanism.181|54|0更新时间：2020-08-11
- 摘要：The InGaAsP/InP double-heterostructure (DH) light emitting diodes are interesting for the use in optical communication systems operating in the wavelength range of l-1.6μm. In present work, we have investigated the dependence of characteristics of LED operating at 1.27-1.3μm on the devices structure and fabrication method. Particularly, we have examined the proporties of the heterostructure prepared by using different dopants In-Zn, Mg and Zn, for the p-InP confining layer. The DH wafer was grown by liquid-phase epitaxy on (100) n-type (Sn doped) substrate. The DH structure consists of a 5-6μm thick n-type (Sn doped) InP buffer layer,an undoped inGaAsP active layer, a 1-2μm thick Zn, In-Zn or Mg-doped InP confining layer. The position of p-n junction and concentration profile of DH wafers were measured by electrochemical C-V method. The InGaAsP/InP DH LED’s have been fabricated. The output power of the devices are 1-2mW (at 100mA), the emitting wavelength λ is 1.27-1.3μm.The results show that using the In-Zn alloy or Mg as p-type dopant, location of p-n junction can be accurately controlled these devices have normal parameters, but using Zn as the p-type dopant the misplaced p-n junction is observed, and these devices have an anomal characteristics.125|61|0更新时间：2020-08-11
- 摘要：GaAs/AlGaAs quantum well materials have been greatly improved for the optoelectronic devices applications. The purpose of this paper is to report the recent research results on the MBE heterojunction materials, using the methods of the X-ray topography and photoluminescence (PL).Double crystal X-ray diffractive technique is used to study the MBE growth GaAs/AlGaAs quantum well (QW) epitaxy layers with the X-ray topography. Defects and dislocations can be found from ths topography images, and it is shown that the quality of this MBE grouth QW materials is strongly related to the growth temperature and the interface properties. The uniformity of this QW materials can be improved greatly by choosing suitable temperature and growing strain superlattices between the substrate and the epitaxy layers. The general samples were grown at temperature of 580℃ and the improved ones were grown at 680℃ with eight strain superlattices layers. Some grown cross dislocations distributs the directions of [110] and [110], which are projected from the climed dislocations in the growth layers, can be observed in the general MBE samples with a high density. However, in only limited area of the improved samples, for example at the edge or corner, this kind of dislocations can be observed. On most of the area of this samples we can find the X-ray diffraction pattern which lefeis that the epitaxial crystal is fine both in. the uniformity and qualityy. Also, we can find that the stress profile of the improved sample is uniform, v. which cemes frcm the impr vement of the int rface qvality, and resulted from the free of the substrate defects.Lew temperature PL, at UK, is used to study the luminescence properties and the composition distribution in the samples. The PL intensity of the general samples is low due to the high density of dislocations. In the improved sample with strain superlattices. the P’L intensity is one hundred times higher than that in the general one, and we can see the high energy transitions from n=1 and n=2 of the QW confined effects. The PL intensity profile is greatly improved at the same time, which means good uniformity there.The Al composition of the heterojuncirn layer AlGaAs was studied by both the X-ray and PL measurements. A little difference can be found in both of the different growth samples. However, in the improved case, the Al composition difference in only in the order of 0.01 at whole wafer,at least only a half of that difference in the general case.Conclusion. The MBE growth GaAs/AlGaAs QW materials can be improved by the choice cf suitablle temperature and imrtion of a series strain superlat-tices layers between substrate and the epitaxy Layers. X- ray topography and PL are both very useful in the diagnosis of the teterojvr.ction crystals to study the dislocation distribution, inteiface propeities and uniformity without damaging sample.99|67|0更新时间：2020-08-11
- 摘要：The present paper shows that the reagent 2,9-dimethyl-l,10-phenanthroline (which we called as new copperon) reacts with hydrogen peroxide in alkaline solution, in the presence of metallic ion, such as Cu(Ⅱ), Pb(Ⅱ), Cod), Fe(Ⅲ) and Ni(Ⅱ) respectively, as a catalyst to produce chemiluminescence of a greenish color. The mechanism of this chemiluminescence reaction has been discussed in the present paper and is believed that a peroxy-icn is formed from hydrogen peroxide by the catalytic reaction of the complex of Cu(Ⅱ) with the new coppercn in the process, and the peroxy-ion is then reacts with the new copperon to produce the chemiluminescence emission. The product of this chemiluminescence reaction has been separated out by thin layer chromatc-graphy and determined by various methods, such as UV, IR and fluorescence spectrophotometry respectively.In addition, the analytical application of this new chemilumineselce reaction has been carried out in our laboratory, and the determination of Cu(Ⅱ) with the chemiluminsecence system is shown in this paper. The lower detection limit of Cu is e×10-9. The linear range of response is 1×10-8 to 4×10-7g/ml. No effect of foreign ions, except certain, amounts of Co(Ⅱ), Mn(Ⅱ) Ni(Ⅱ) Cd(Ⅱ), and Cr(Ⅲ) respectively for the determination of 0.1 ppm Cu(Ⅱ). It can be applied satisfactorily to the determination of Cu in alumnum alloy.143|68|0更新时间：2020-08-11
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