正向高密度脉冲电流激发下ZnSe MIS二极管中的自由激子发光

本文测量了在77K和正向脉冲电流密度为50～500mA/mm2的激发下,ZnSe MIS二极管的电致发光光谱.首次在高电流密度激发下的ZnSe晶体的电致发光光谱上,观测到自由激子与自由激子间(Ex-Ex)的散射.本中根据自由激子的动能分布,讨论了2LO声子协助的自由激子伴线的形状,发现当激发电流密度增高时,自由激子的有效温度大于晶格温度,这可归结为激子与激子间的非弹性散射.     

气相外延ZnSe单晶膜的自由激子发光

本文在77K和N2激光器3371谱线高密度激发的VPE ZnSe单晶膜上,首次得到了起因于自由激子与自由激子(Ex-Ex)散射的发光谱带(P带),理论拟合了该谱带的形状并讨论了它的发光特性。文中把在选择的VPE ZnSe外延单晶膜中得到P带的起因归结为这些ZnSe外延单晶膜的质量较高。     

Excitonic emission in highly excited lead iodine

Excitonic luminescence in PbI₂ has been investigated in the temperature range between 77 and 300°K under high excitation by a nitrogen laser. A single emission band is observed which, at low pumping, is centered at the free exciton energy. When the excitation intensity is increased, the band broadens and shifts towards lower energies. These facts are interpreted on the basis of an exciton-electron interaction.     

Excitation characteristics of the IR luminescence in CU2O

Detailed luminescence excitation characteristics of the long-wave (0.93 μm), medium-wave (0.82 μm), and short-wave (0.72 μm) emission peaks in cuprous oxide were studied under pulsed dye laser excitation. The results show that the emission spectrum at 193 K contains only two peaks at 0.93 and 0.72 μm for excitation wavelenghts less than 5800 Å, and that for excitation wavelengths 5800 Å and longer an emission peak also appears at 0.82 μm. This medium wave band increases relatively faster with increase in wavelength until it becomes the dominant luminescent peak at an excitation wavelength of 6350 Å. All three emission peaks have much narrower excitation curves at 300 K than at 77 K, with the peak excitation wavelength shifting to longer wavelengths at higher temperature.     

The effect of temperature on the parameters of the phosphorescence spectrum of naphthalene in glassy toluene

The temperature shift and the shape of the 0–0 band of the phosphorescence spectrum of naphthalene in glassy toluene are studied in the presence and absence of excitation migration over triplet levels. In the absence of excitation migration, an increase in the temperature from 77 to 110 K has no effect on the position of the maximum of the 0–0 band and on its shape, which is a Gaussian. In the presence of migration, the shape of the 0–0 band at 77 K is non-Gaussian; upon heating to 110 K, it becomes Gaussian, and the band maximum is shifted toward the short-wavelength range by 35 cm^?1. It is shown that the reason for this is thermal activation of excitation transfer, in the course of excitation migration, to high-lying triplet levels within the range of their inhomogeneous broadening.     

钡钇氟化物中Eu2+离子的激发光谱和发射光谱

在298和77K下分别研究BaYF5(BaF2·YF3)中Eu2+的激发和发射光谱。Eu2+的发射光谱中,除了一个属5d-4f跃迁的宽发射带外,还有一组6PJ→8S7/2的4f-4f跃迁窄谱线发射。它们的发射强度与Eu2+的浓度和温度有关。由於Eu2+从4f7基态跃迁到4f65d1态产生两个宽的激发带,4f65d(eg)和4f65d(t2g)。实验证实,Eu2+的6PJ→8S7/2的窄谱线发射主要来自高能级的t2g激发能弛豫的结果。     

Luminescence properties of BaWO4 single crystal

UV excited photoluminescence from BaWO₄ (BWO) single crystals has been investigated in the temperature range of 77-300 K. The presence of two emission bands in the UV and blue spectral regions is observed under excitation by 230 nm at room temperature. The observation of UV emission band at room temperature is a novel result. The thermal treatment at elevated temperatures under air or vacuum is observed to influence the optical and luminescence properties of the crystal. The changes brought about by annealing in air are found to be reversible. However, in vacuum annealed samples the UV emission is completely quenched.     

Relaxation dynamics of Mn2+ intraion excitation in Cd0.5Mn0.5Te: Dependence on the optical pumping level

A study is reported of the Mn²⁺ intracenter 3d luminescence in a dilute Cd_0.5Mn_0.5Te magnetic semiconductor at pulsed excitations of up to 3.5 MW/cm². At high excitation levels and at a temperature of 77 K, the kinetics varies strongly over the emission band profile. The luminescence decay curve can be resolved into a fast and a delayed component, which correspond to the excitation of extended and localized states in the manganese ion system. The fast relaxation of the extended states is largely determined by the up-conversion. As the temperature is lowered, the contribution of the fast component at the center of the emission band and in its low-energy wing decreases because of the weakening role of the extended states lying above the mobility edge.     

高密度激发下ZnTe晶体中与自由激子有关的发射

在77—300K温度范围内,用N2分子激光器的3371Å谱线激发未故意掺杂的p型ZnTe晶体,得到了与自由激子有关的发射。发现随着激发密度的增加,其发光光谱的峰值位置红移而谱带的半宽度展宽,这些结果可以用Ex—e和Ex—Ex的相互作用来解释。     

激子转移对GaP:N发光热猝灭过程的影响

本文研究了20K-120K范围内GaP:N束缚激子发光与温度的关系,从实验结果发现,各发光中心之间存在着激子转移.初步分析表明,采用带带激发方式,激子转移会导致深束缚中心的热激活能拟合值偏高,其发光热猝灭是由于空穴的热离化所造成的.     

LiYF4:Nd3+中脉冲光泵浦的上转换蓝光

本文报道利用578.4nm的脉冲光泵浦,在室温和77K下,观察到LiYF4:Nd3+单晶中的上转换蓝光。由发光强度与泵浦光强度平方的直线关系,确定此上转换过程是双光子过程.通过对吸收谱和激发谱以及衰减曲线的研究,确定其上转换激发机制为两步激发和能量传递上转换。     

Luminescence of solid cyclic polynitramines

The solid form of the cyclic polynitramines known as RDX and HMX have a weak absorption band in the near ultraviolet which is not observed in spectra of the solvated compounds. Fluorescence measurements on solid samples of these materials show a weak emission, the excitation spectrum of which corresponds to this absorption band. Phosphorescence measurements on the solids at 77 K reveal a long-lived emission, the excitation spectrum again corresponding to the weak absorption band. The absorption and the luminescence bands are attributed to charge-transfer self-complex formation in the solid state, and estimates of the energies of the emissive singlet and triplet excited states are given.     

Photoluminescence of mercurous halides

Mercurous halides show strong orange luminescence at 77°K when excited at energies above the fundamental absorption edge. At room temperature this luminescence is strong only in the chloride and bromide. Spectral features, including band maxima and half widths of both excitation and emission spectra are also temperature dependent. At 77°K a strong green luminescence was observed from the Hg₂Cl₂. Both Hg₂F₂ and Hg₂I₂ exhibited weak green emission, while no luminescence was observed from Hg₂Br₂ in this spectral region. The common orange luminescence is tentatively attributed to structural defects unique to mercurous salts, while the green emission is ascribed to an unspecified impurity center.     

Photoluminescence in powdered crystalline GeSe2

The decrease of photoluminiscence (PL) intensity under continuous excitation in powdered crystalline GeSe₂ was observed at 77 K. The intensity of PL decreased by ～ 50 % in 2.10³s. The characteristics of the PL band for the powdered samples at 77 K are identical with those for crystals, but the temperature dependence of the PL intensity and the peak of the PL spectrum in the temperature range 77–200 K for powdered and bulk crystalline samples are different.     

InP中和C带有关深能级的近红外光致发光

本文用红外光致发光方法研究了InP中与C带有关的深能级的性质和起源。峰值位于价带上0.34eV(77K)附近的宽谱带普遍存在于不同方式生长的InP外延层和掺Sn与不掺杂的衬底中,且与P空位引起的复合缺陷有关。 通过红外光致发光强度对温度的依赖关系得到C带的热激活能为0.17eV。这刚好与采用σ函数来描述深能级的Locovsky模型相吻合,光谱线型与温度猝灭的量子力学位形坐标模型拟合,得到与C带有关的深能级hv=0.02eV,S=8。     

CdTe/CdZnTe多量子阱激子复合动力学性质的研究

报道了分子束外延制备的高质量CdTe/Cd_0.64Zn_0.36Te多量子阱结构的光学性质,由变温光致发光光谱讨论了随温度升高辐射线展宽和辐射复合效率降低的机理.在变密度激发的皮秒时间分辨光谱中,发现不同激发密度下发光衰减时间不同,并研究了它的机理.在高激发密度下观测到n=2的重空穴激子发光. 关键词：     

Injection of the edge electroluminescence in ZnSe MOS diodes

Injection luminescence and related properties of metal-ZnO-ZnSe-metal tunnel diodes are described. The edge emission of ZnSe is studied in the temperature range 30-300 K with respect to: a) band shape b) coupling strenght parameter, c) time resolved spectra and d) temperature dependence.External quantum efficiecies of the blue band of 2.61 × 10^-5 have been observed at 77 K. The lowest voltage threshold observed for blue band emission is 1.5 V.The relation between the electroluminescence and electrical characteristics of the MOS diodes are discussed.     

Room-temperature electroluminescence from erbium-doped amorphous hydrogenated silicon

We have studied electroluminescence (EL) in the amorphous silicon-based erbium-doped structures under reverse bias in the temperature range 77–300 K. The intensity of electroluminescence at the wavelength of 1.54 μm exhibits a maximum near the room temperature. The excitation of erbium ions occurs by an Auger process which involves the capture of conduction electrons by neutral dangling bonds (D⁰-centers) located close to erbium ions. The stationary current through the structure is kept by a reverse process of thermally activated tunnel emission of electrons from negatively charged dangling-bond defects (D⁻-centers) to the conduction band of the amorphous matrix. A theoretical model proposed explains consistently all of our experimental data.     

Cd3Al2Ge3O12锗酸盐石榴石中Cr3+的宽发射带和R线

本文首次报道了掺杂不同浓度Cr3+的Cd3Al2Ge3O12锗酸盐石榴石在295K和77K温度下的荧光光谱、Cr3+的鲜红色宽带发射强度与激励功率的关系及荧光衰减.发现在Cr3+的荧光光谱中存在从15400cm-1延伸到11400cm-1附近的宽带、两组R线及R线的Stokes和反Stokes振动光谱.295K时以宽带发射为主,77K时宽带明显减弱,R线发射显着增强.在Cd3Al2Ge3O12石榴石中,Cr3+离子的光谱是由两个性质上稍有差异的Cr3+中心发射组成的.     

Multiplication of electronic excitations in AgCl crystals

The kinetics of pulse conduction in silver chloride single crystals is investigated in the temperature range 12–300 K upon picosecond excitation with x-ray bremsstrahlung. It is found that the experimentally observed concentration of conduction electrons is nearly twice as high as the concentration of electron-hole pairs generated by an exciting pulse. This effect is associated with the chain multiplication of band charge carriers.