最新刊期
卷 11 ， 期 3 ， 1990
- 摘要：To methods have been used to determine the non-radiative transition probability of 5D1 state of Eu3+.(1)Partlo's method.The quantum efficiency from state A to state B(Fig.4) can be obtained from the absorption spectrum and the excitation spectrum according to formula(1), where PA and PB are the power absorbed by A and B respectivel,PAL and PBL are the emission intensities of L generated by excitation to A state and B state respectivel,and vA and vB are respectively the energies(in wavenumber) of A and B. The absorption spectrum of the phosphor can be determined from the diffuse reflection spectrum according to our previous work. The quantum efficienc from 5D1 to 5D0 is then determined to be 79.6%. The non-radiative transition probability of 5D1 is 5.64×10-3/sec.(2)Judd-Ofelt's method. In calculating the intensity parameters j(j=2,4,6) from the emission spectrum according to J-O theory the index of refraction n of LaOCl(which is unkno n) is evaluated by the method we proposed in a recent paper.The nonradiative transition probability of 5D1, which can be obtained from the radiative transition probability of 5D1 to 7Fj (for all j values) and the measuied lifetime, is 5.28×10-3/sec,which agree fairly well with the fromer value.It appears that the first method is more convenient and probably more accurate.114|102|6更新时间：2020-08-11
- 摘要：For the wide class of phosphors doped with rare earth elements such as Sr3(PO4)2:Eu, BaFCl:Eu, Ba3(PO4)2:Eu, YVO4:Eu, Y3Al54O12:Ce, YPO4:Tb and Y2SiO5:Ce, thermal and optical ionization energies of the trapping centers were determined. It was shown that the difference in optical and thermal energy depth of traps exceeded significantly that in ZnS and might serve as a characteristic of the ionic coupling degree of a compound.For most trapping centers the photothermal mechanism of charge release by optical stimulation was revealed.Complex investigations of Sr3(PO4)2:Eu, Ba3(PO4)2:Eu and Y2SiO5:Ce luminescent properties allowed to reveal that exciton origin of UV-emission detected in these phosphors.119|31|0更新时间：2020-08-11
- 摘要：ZnSe-ZnS strained-layer supcrlattices were thought to be an important blue optoelectronic material. The SLS has been developed quickly so far. But the optical absorption spectra in ZnSe-ZnS SLS were very difficult to observe, because of the use of GaAs substrate which cannot transmit photons above 1.5eV. Y.Kawakami et al. have observed the n=1 subband heavy, light hole's excitons in the absorption spectra of ZnSe-ZnS SLS on Al2O3 at 4.2K.115|65|0更新时间：2020-08-11
- 摘要：Optical bistability(OB) in semiconductors is of increasing interest in both basic aod applied lesearch. Much is known about optical nonlinearity and OB, and several kinds of optical bistability have been observed in CdS crystals and films. This paper leports the optical properly and bistability in CdS epilayers grown on CaF2 tiansparent substrates by vapour phase epitaxy(VPE) for getting large area, uniform and high quality samples. The source material v as the high quality CdS single crystal and the superpurity H2 gas yas used as carrier gas. The freshly cleaved CaF2 substrate was put on the deposit range, then raised the lemperature of source material to 700-800℃ and that of substrate to 500-600℃ in H2 flow. The emission and transimission spectra were measured by 44W grating monochro-meter and recorded by cooled pholomultiplier. The 5145? line of Ar+ laser chopped into 6ms light pulses was focused to the radius of about 50um for OB measurement at room temperature.99|48|0更新时间：2020-08-11
- 摘要：ZnSxSe1-x is one of the most promising materials for optoelectronic devices for use in the region between blue and ultraviolet.There have been many reports on the luminescence of ZnSxSe1-x bulk crystals and epilaycrs.Leigh et al.and Goto et al. grew ZnSxSe1-x. cpilaycrs by VPE method on GaAs and GaP substrates, respectively. Goto ct al. and Stutius studied the pho-toluminescence(PL) spectra of ZnSxSe1-x cpilayers. In this paper, growth and PL spectra of VPE ZnSxSe1-x epilayers on GaAs substrate are studied.100|31|0更新时间：2020-08-11
- 摘要：The high peak power and continuous nature of the synchronously pumped CW dye laser allow the genetation of a sensitive and precise two-photon excitation response,and the wide tunability range allows acquisition of two-photon excitation spectra. It has been determined that the cavity dumped veision of the laser yields the best performance for two-photon spectroscocy and offers the most versatile output method.99|60|0更新时间：2020-08-11
- 摘要：The high-molecular additive-polyglycol (mol.wt. 6000) being added into the solution of dye Rh-6G and water, the fluoiescencc of the dye was enhanced. In order to clarify the mechanism of the enhancement effect, the spectroscopic properties oyf de solution with and without additive v ere examined. For the dye solution without additive, the absorption spectrum of low concentration dye solution shows a main peak centred at 540nm.When the dye concentration goes up, a new absorption peak(around 500nm) appears at the short wavelength side to the previous one. The new peak may be attributed to the dimer of the dye molecules and the previous one is due to the dye monomer. Both the fluorescence intensity and the monomer absorption show paralell concentration dependance. They increase with the concentration at lower concentration range, and gradually saturate and finally decrease with dye concentration at higher concentiation range. It is concluded that the mechanism for concentration quenching of the fluorescence of the dye solution of Rh-6G and water is the dimer formation of the dye molecules.For the dye solution added with polyglycol, the dimer absorption peak decreases and nearly disappeares at higher amount of additive, and the monomer absorption peak increases, in accordance with the increase of fluorescence. The fact means that high-molecular additive effectively prevents the dye molecule from forming dimer and hence incieases the fluorescence of dye, which is related to the dye monomer. The experiments manifest that the fluoiescence enhancement can reach 300% and accordingly the laser output increases.Our results imply that it is possible to use high-molecular addtives to improve the performance of dye laser and to control various physical propeities of the dye solution.106|61|1更新时间：2020-08-11
- 摘要：GaAs0.6P0.4:Te is an important photo-electronic material. Recently increasing altension has been paid to the deep centeis in it. But the studies on the complex properties and microscopic structures of these deep centers are not efficient. In this paper we report the results of deep centers in GaAs0.6P0.4:Te studied by DLTS, steady and transient photo-capacitance, OITS and initial slope method. The photo-electronic properties and eleclron-phonon couple effects of the deep centers have been analyzed.121|43|0更新时间：2020-08-11
- 摘要：Ridge waveguide laser diodes al 1.55μm wavelength ale described in this paper. LDs have been obtained by LPE technology with CW threshold of 100 mA al room temperature,and the single transverse mode operation of 5 mW. The spectral line width of the LDs is less than 2?. The rise lime for impulse response of the LDs is about 100 picoseconds. Factors affecting the Jth, such as the thickness d and doping level of active layer and so on, are analyzed. The relation of output mode of the LDs to device structure is also discussed.99|66|0更新时间：2020-08-11
- 摘要：The charge storage in DH laser driven by pairs of bell-shape pulse current has been investigated. By using the model of positive half-period of Sinusiod to describe the bell-shape pulse current, we calculated the threshold cunent of the second pulse as a function of the time spacing between the pulses. The results of calculation agree with experiments satisfactorily.106|66|1更新时间：2020-08-11
- 摘要：Using the methods of X-ray double crystal diffraction and X-ray topography as well as photoluminesccnce (PL), the influence of mismatch of InGaAsP/InP heterojunction interface lattice on LPE crystal quality was studied. The following results are obtained:1)X-ray double crystal diffraction shows that the halfpeak width of the rocking curve profile of epitaxial layer is five limes larger than that of the substrate when the lattice mismatch perpcndicular to the growth direction (001)(ΔaL/as) is larger than 3×10-3. However, the half-peak width of the rockingcurve piofile of epitaxial layer is the same as that of substrate when (ΔaL/as) is less than 1.5×10-4. A lot of defects and dislocations can be found from (422) surface X-ray reflection topography images in epitaxial layer of sample No.2.On the contrary, a little of defects and dislocations can be found in the sample No.1.2) Photoluminescence spectrum indicates that the band edge PL intensity of sample No.2 is lowei than that of No.l under the same expeiimenlal condition. A possible mechanism is related to the presence of a suiface layer with high recombination velocity. The cause of this high surface recombination velocity possibly leads to a high concentration of nonradiative recombination centers and ladialive recombination deep center. It is found that sample No.2 has a deep center 0.75 eV luminescence band which related to the lattice mismatch.InGaAsP/InP heterojunction interface lattice mismatch is an important factor that has influenced upon epitaxial crystal quality. This kind of lattice mismatch will lead to the inciease of impurity condensation, dislocation and defects as well as radiative recombination deep centeis in LPE processing.107|44|0更新时间：2020-08-11
- 摘要：CdSe1-xTex photoconductive films were prepared by the vacuum-evaporated method using the mixture of CdSe and CdTe.The photoconducting properties of CdSe1-xTex films (thickness about treated at the temprature of 550-650℃ were investigated.CdSe and CdTe powders were deposited onto the chemically cleaning glass or quartz substiates at the temperature of 100-150℃ and in vacuum of 10-5 Torr.106|42|0更新时间：2020-08-11
- 摘要：Thin films of SnO2 can be prepared in a highly conductive form with the important properly of being highly transparent in the visible and near-IR regions of the solar spectrum. Potential applications of the thin film are coatings in heat minor systems as well as in solat cell technology. In this paper, we report the effect of annealing temperature on the photoluminescence of SnO2 films. Experimental samples were made by the spraying method that involves the decomposition at high temperature (around 500℃) of a mineral compound such as SnCl4·5H2O dissolved in a solution of water and alcohol. Water is used here as an oxidizing agent.Experimental results show that the annealing process has a significant effect on the photoluminescence of SnO2 films. The influence is very different in oxygen and nitrogen. A "red shift" of the peaks of photoluminescence appeals when samples are annealed in O2 atmosphere at 300-500℃,while the emission peaks of annealing samples in N2 or H2 exhibit a "blue shift". The change of emission peaks of the SnO2 films may be attributed to the change of oxygen vacancies in SnO2 films during annealing. Undoped tin oxide films have n-type extrinsic conduction. The Sn2+ ions, associated with the oxygen vacancies, and the residual Cl-ions are both capable of being electronic donors and probably both are responsible for this extrinsic conduction. The free carrier concentration of the conduction band changes with changing oxygen vacancies after annealing in oxygen or nitrogen. The change of the earlier concentration causes the change of optical gap energy according to Bursein effect.The peaks of photolumine-scence are then shifted with the change of optical gap energy after heat-treatment.93|40|0更新时间：2020-08-11
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