最新刊期
卷 5 ， 期 2 ， 1984
- 摘要：In ionic crystal, the frequency of lattice vibration depends on the wave vector, but since professor Huang[1] discussed the long wave vibration for optical branch in an ionic crystal, the frequency of longitudinal optical phonons has been considered to be constant.The author has discussed the effect of the dispersion of the longitudinal optical phonon on the property of a polaron. In this paper,the effect of the dispersive properties of longitudinal optical phonon on the properties of an exciton is further discussed.131|86|0更新时间：2020-08-11
- 摘要：The temperature dependence cf the pbotoiuminescer.ee in GaPiN has been investigated in the range of 20K-120K. The following experimental phenomena show that there would be exciton transfer between different luminescent centres in GaP:N. (1) With the increase cf temperature from 20K to 60K, the emission intensity of higher energy band (18760cm-1-18280cm-1) decreases rapidly, while that of lower energy band (17640cm-1-17050cm-1) increases. However, the total intensity of all luminescent lines decreases slowly when the temperature increases from 20K to 60K, and decreases rapidly when T exceeds 60K. (2) As the temperature is raised from 20K to 60K, for the deeper binding centres (e.g. NN1,NN3) the emission intensity increases appreciably, (3) The NN1 line and its phonon sidebands have been observed under A line exciting. This selective excitation experiment shows that at 77K there is exciton transfer from the isolated N to the NN1 pair.147|263|0更新时间：2020-08-11
- 摘要：In this paper, a method is suggested to analyze the photocapacitance transient which may relate to several deep levels, and the photoionization cross sections, energy positions and concentration of deep levels in 1MeV electron-irradiated GaP :N LED have been measured by photocapacitance technique. And the roles of these deep levels in electron-hole recombination are specified.Photocapacitance experiments showed that certain deep levels in GaP are resulted from electron-irradiation, and that the photocapacitance transient which may include a number of electron or hole emissions from these deep levels is almost always non-exponential. If the electron and hole transitions between deep levels may be neglected, the total transient can be expressed as the sum of the exponential transients corresponding to the deep levels from which electrons or holes are excited to conduction/valence band by light.99|76|0更新时间：2020-08-11
- 摘要：The deep levels of GaAs1-xPx LEDs and their effect on the luminous efficiency are studied by DLTS. The block diagram of apparatus for measuring DLTS is given. The calculating formula about the concentration, depth and capture cross section of deep levels and correlation between the luminous efficiency and minority life time are introduced. Three kinds of GaAs1-xPx LEDs with different luminous flux, 5.1, 0.46, and 1 mlum at 10mA,designated as 1#,2#,3#LEDS are compared.Their concentration of shallow donor is nearly equal, namely |ND-NA| = 2.1~3.1×1017cm-3.Experi-mental results show that the 1# LED with high luminous flux has only one strong and one weak peak located at 0.15 and 0.33eV below the conduction band, no hole deep level is detected. The other LEDs with lower luminous flux have not only more than two electron peaks, but also two hole peaks. The calculated results indicate that it is difficult to ascertain correctly the level depth if there are two kinds of deep level having very close location in the band gap, owing to the emission of electron(or hole) from the levels simultaneously. The parameters of deep levels, luminous flux and others data are listed in Table 1. The luminous efficiencies are proportional to the carrier life-times, qualitatively. The longer the carrier life time,the higher the luminous flux. But larger differences are still discovered by quantitative comparisons of these data, especially for 2# LED.For example, ratio of the luminous flux for 1# and 3# LED is 4.1, the ratio of their life time is~3. But the ratio of the 1# flux to that of 2# is~10; their ratio of life time is~240.The larger difference in the latter case is probably caused by poor p-n junction preparation resulting in severe leakage current.113|39|0更新时间：2020-08-11
- 摘要：Photoluminescence and its temperature dependence of unintentionally doped zinc telluride crystals grown by sublimation method have been studied. Photoluminescence spectrum at room temperature, which is excited by the 4880Å line of'Ar+-ion laser, contains only one band centered at 18190cm-1 and at liquid nitrogen temperature consists of four bands peaking at 19054cm-1, 18739cm-1, 18528cm-1 and 18314cm-1, respectively.According to the energy and intensity dependence, the bands of 18528cm-1 and 18314cm-1 in PL spectrum observed at 77K are identified as the one LO and two LO phonon associated, respectively, replicas of the band of 18739cm-1.The temperature dependence of the photoluminescence spectrum shows that the band of 18739cm-1.115|72|0更新时间：2020-08-11
- 摘要：In this paper, the series of absorption,excitation and emission spectra of REP5O14 (RE = Ce3+, Pr3+, Nd3+, Sm3+, Eu3+, Gd3+, Tb3+, Dy3+, Ho3+, Er3+, Tm3+, Yb3+) single crystals were investigated in a wavelength region much larger than those reported so far. The spectral terms were assigned reasonably, and some mistakes in previous papers were corrected. Particularly, the spectra for GdP5O14, DyP5O14, TmP6O14, YbP5O14 and SmP5O14 were measured in detail. They have not been reported previously. These spectral data will be very useful to understand the properties of REP5O14 crystals and to utilize them.112|36|0更新时间：2020-08-11
- 摘要：Two problems of particle size have been studied in this paper.1. The relationship between the particle size of raw materials ZnS and that of corresponding ACEL phosphors (Zn,Cd)S:Cu.2. The relationship between the particle size of (Zn,Cd)S:Cu and its ACEL luminance.Twelve types of ZnS raw materials with different particle sizes were used in the experiments. The phosphors were prepared at about 850℃ in sulfur atmosphere. The particle size distribution of raw materials and corresponding ACEL phosphors (Zn,Cd)S:Cu were measured by means of sedimentation method.The central particle size d50, the logarithmic standard deviation Ina and the sediment mean particle size d were calculated. The d50 and Ina indicate the centralization position and the dispersive degree of particle size in logarithmic normal distribution, respectively; q indicates the position of centre of gravity in particle weight, distribution.Using raw materials with almost same impurity content under the same conditions,we have the following results.103|54|0更新时间：2020-08-11
- 摘要：This paper describes the use of a 1P801 SBC in the investigation on thermoluminescence and temperature dependence of luminescence to fulfil the requirement of automatic temperature control and automatic measurement of physical parameters. The system may acts as a constant temperature controller in order to study the relations between luminescence characteristic and temperature. It also may give heating rates of 4℃/min, 6℃/min,10℃/ min and 12℃/min in order to study the depth of trap level and their distribution in samples. In addition, the computer may carry out the measurement of luminescence intensity and the calculation of the depth of trap level.Adopting computer Direct.Digital Control (DDC) and Sequence Control Counter (SCC), the system is flexible for changing or increasing its functions.This can be done simply by changing the system software.93|52|0更新时间：2020-08-11
- 摘要：Ce3+ ion has a 4f configuration.The ground state consists of doublet 2F5/2 and 2F7/2. The lower excited states are the crystal-field components of the 5d configuration.Ce3+ emission is due to a 5d-4f transition. Usually the emission consists of a broad band with two peaks in the long-wavelength ultraviolet region.The 5d-4f transition is an allowed electric dipole transition and therefore the decay time of the fluorescence is very short (<10-7sec).In a number of cases the 5d level varies strongly with host lattice.The position of Ce3+ emission bands can be in the region from ultraviolet to visible.The position of Ce3+ emission bands has something to do with elec-tronegativity of ligands which is directly coordinated with Ce3+ ion.As the electronegativity of the ligand (F.O.S) decreases, it moves to long wavelength.The position of Ce3+emission bands in several host lattices are related to the crystal-field splitting, the cation, the indirect coordinated ligand which is in negatively charged ion group etc.The energy transfer and sensitization of Ce3+ ion have been described. These results will provide the basis for material design.107|59|0更新时间：2020-08-11
- 摘要：Energy transfer between different kinds of rare earth ions has been studied in various hosts coactivated by Ces and Tb3+17-14. It has been found that in all cases the excitation energy transfers from Ce3+ to Tb3+. In investigating the. photoluminescence of YAG:Ce,Tb phosphors, however, excitation energy is found to transfer from Tb3+ to Ce3+. This is shown in Fig.5 and 6 where a new excitation band appears at 270nm for YAG: Ce,Tb when the intensity of Ce3+ emission at 520nm is monitored. This band excites Tb3+ luminescence quite efficiently in YAG:Tb3+ (Fig.3) but is almost ineffective for the Ce3+ 520nm emission in YAGsCe3+ (Fig.4), unless the latter is codoped with Tb3+. These results imply that the energy absorbed by Tb3+ ions transfers to Ce3+ ions.108|56|0更新时间：2020-08-11
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