Squeezing of Phonons in Photon-Phonon Interaction via Anti-Stokes Light

A model of the photon-phonon interaction via anti-Stokes light has been proposed to investigate the squeezing properties of phonon mode. The behavior of initial anti-Stokes light with complex statistics has been studied. It is shown that the squeezing of phonon mode can appear under certain conditions.     

Temperature dependence of positron lifetime in GaAs crystals with defects

Positron lifetime has been measured as a function of temperature in Sidoped GaAs single crystals subjected to various heat treatments. Defects produced by these heat treatments trap positrons. In all the GaAs samples containing defects positron lifetime was found to decrease with temperature in the range from 375 K to 16 K. The decrease is explained as due to the decrease in the trapping rate. The trapping rate is mainly controlled by the diffusion of the positron to the trap. The diffusion constant is determined mainly by the scattering from charged Si impurities.     

Photoluminescence of gallium arsenide electron-irradiated at 20 K

The processes of defect formation in single crystals of gallium arsenide electron-irradiated at cryogenic temperatures (∼20 K) have been investigated by the luminescence method. It is shown that at such temperatures the primary radiation-induced defects, in particular, intrinsic interstitial atoms, can migrate in a crystal and form complexes with their participation. Institute of Solid-State and Semiconductor Physics of the Academy of Sciences of Belarus, 17, P. Brovka St., Minsk, 220072, Belarus. Translated from Zhurnal Prikladnoi Spektroskopii, Vol. 64, No. 1, pp. 122–124, January–February, 1997.     

Far-infrared cyclotron resonance study of neutral impurity scattering in GaAs

Far-infrared laser cyclotron resonance with the help of photoexcitation enables us to separate the electron-neutral donor and electron-neutral acceptor scattering rates in GaAs. Allowing for the complication due to the coexistence of donors and acceptors, inaccuracy due to unknown contribution of phonon scatterings etc., one finds that the electron-neutral donor scattering cross-section is 2.9×10^–11 cm² at 4.2 K, that is 23 times as large as the electron-acceptor scattering cross-section.     

Effects of Weak Localization and Electron–Electron Interaction in GaAs–AlGaAs Heterostructures

The influence of the processes of weak localization and electron–electron interaction in an inhomogeneous two-dimensional electron gas of a single GaAs–AlGaAs heterojunction on the low-temperature transport characteristics in the case of occupation of two quantum subbands has been investigated. The transport characteristics have been interpreted from the viewpoint of a two-layer model taking into account the existence of two bypass conduction channels corresponding to the two-dimensional and three-dimensional electron gas. Both the electrical and optical measurements point to the existence of large-scale fluctuations of the potential, which determine the dependence of the conduction and the Hall resistance of the heterostructures on the magnetic field. It has been established that the weak localization determines the charge transport in a weak magnetic field, and the electron–electron interaction determines this transport in a strong magnetic field.     

Properties of the GaAs–Si Interface in Epitaxy through an Aluminum Layer

The interaction of elements near the interface during epitaxial growth of monocrystalline GaAs films through an aluminum layer is investigated by the methods of x-ray photoelectronic spectroscopy and secondary-ion mass spectroscopy.     

Anti-Stokes luminescence in heavily doped semiconductors as a mechanism of laser cooling

The anti-Stokes luminescence is a mechanism of the optical refrigeration in semiconductor light sources. The heavily doped semiconductors are considered as a material for the laser cooling. The limitation of this mechanism appears to be connected with a transition from the non-degenerate to degenerate occupation. This transition occurs at higher pumping rate (along with the transition to the optical gain and lasing) and at lower temperature. Thus, the limit for the laser cooling can be indicated. The minimal obtainable temperature is about 60–120 K depending on the doping level. The laser cooling of a semiconductor is impeded by the difficulty of extracting the spontaneous emission from a radiating body that is characterized by large angle of the total internal reflection.     

Influence of IR Radiation on the Electron Mobility in Submicron Layers of GaAs

The influence of optical radiation near the impurity absorption band on the electron mobility in submicron doped gallium arsenide layers formed on semiinsulating substrates is investigated. To determine the lowfield mobility of carriers, a method is used which is based on measurements of the mutual conductance and series resistances of a fieldeffect transistor at low sourcetodrain voltage. It has been established that the electron mobility increases under IR illumination as a consequence of decrease in electron scattering, and this is related to the photoneutralization of deeplying chrome acceptors.     

近海微塑料含量的相干反斯托克斯拉曼光谱成像研究

由于塑料工业的发展,微塑料成为一种主要的环境污染物.它在自然界中不易降解,对人类的生存环境及健康都存在不可忽视的潜在危险.因此,环境中微塑料的检测和分析,成为了近年来研究的热点问题.目前人们大多数采用浮选法、密度分离法、离心法等方法提取微塑料,然后放在显微镜下进行目视观察,并结合拉曼光谱分析、傅里叶红外光谱分析、高光谱...     

Incorporation of deep centres in VPE GaAs

The incorporation of deep levels in high purity vapour phase epitaxy (VPE) GaAs is studied as a function of the crystal growth conditions. Two deep levels, at 0.4 eV and 0.75 eV above the valence band, are investigated using photocapacitance. It is shown that their concentrations are always equal and vary together as a function of the AsCl₃ mole fractionX. Two regimes are observed, respectively, characterized by different variations of the total deep level concentrationN _T:N _TαX for lowX, andN _TαX⁻² for highX. In this last range,N _T andN _D are found to vary similarly. This work has been supported by the DRME.     

Numerical Comparisons of Terahertz Radiation from GaAs and GaAs: As+ Substrates

In this paper, we have numerically analyzed the ultrafast change of local fields on the surfaces of a large-aperture photoconducting (LA-PC) antenna with GaAs and GaAs: As+ substrates. We find that the ultrafast screening of photogenerated carriers to the externally applied electric field has different effects on the saturation of THz radiation as the function of the laser fluence in the near and far field, respectively. Both screening effect of photocarriers and radiation effect are important in forming the saturation phenomena in the case of near field. But in far field, only the radiation effect is important.     

高能电子和正电子在晶体沟道中的辐射

介绍了高能电子和正电子在晶体中的沟道辐射,对超相对论电子和正电子在周期弯曲晶体中的相干辐射进行了分析,并提出了初步的实验设想. The channeling radiation of high energy electrons and positrons in crystals was introduced. According to the new idea proposed by A.V.Korol, the coherent radiation of ultra relativistic electrons and positrons channeled in periodically bent crystals was analyzed. The characteristics of the radiation were obtained by using classic electromagnetic theory and a tentative experimental plan for testing was suggested.     

钨酸铅晶体的辐照损伤研究

报道对钨酸铅晶体作低剂量辐照损伤研究的实验装置、方法、和结果.利用北京计量科学研究院的小型⁶⁰Co放射源对4块钨酸铅晶体作了辐照损伤的实验,发现光产额随辐照剂量的增加呈现指数衰减,最后趋于饱和.     

半绝缘砷化镓单晶中碳微区分布的研究

通过AB腐蚀（由Abrahams和Buiocchi发明的腐蚀方法，简称AB腐蚀）、KOH腐蚀，经金相显微镜观察、透射电子显微镜能谱分析、电子探针x射线微区分析，对液封直拉法生长的非掺 半绝缘砷化镓单晶中碳的微区分布进行了分析研究.实验结果表明，碳的微区分布受单晶中 高密度位错网络结构的影响.高密度位错区，位错形成较小的胞状结构，且胞内不存在孤立 位错，碳在单个胞内呈U型分布；较低密度位错区，胞状结构直径较大，且胞内存在孤立位 错，碳在单个胞内呈W型分布. 关键词： 半绝缘砷化镓 胞状位错 碳受主     

Effect of heavy ion irradiation on the interface traps of AlGaN/GaN high electron mobility transistors

AlGaN/GaN high electron mobility transistors (HEMTs) were irradiated with heavy ions at various fluences. After irradiation by 2.1 GeV¹⁸¹ Ta³²⁺ ions, the electrical characteristics of the devices significantly decreased. The threshold voltage shifted positively by approximately 25% and the saturation currents decreased by approximately 14%. Defects were induced in the band gap and the interface between the gate and barrier acted as tunneling sites, which increased the gate current tunneling probability. According to the pulsed output characteristics, the amount of current collapse significantly increased and more surface state traps were introduced after heavy ion irradiation. The time constants of the induced surface traps were mainly less than 10 μs.     

钨酸铅晶体抗辐射性能的测试

大型强子对撞机(LHC)运行时具有很高的辐射背景,为达到所要求的电磁量能器的测量精度对研制中的钨酸铅晶体的抗辐照性能提出了很高的要求.本文主要介绍了用⁶⁰Co的γ射线,在相应的辐照剂量率辐照下,对几种全尺寸(23cm长)钨酸铅晶体抗辐照性能的评估和测量方法.研究了晶体在侧面辐照条件下对光产额及纵向发光均匀性的影响,给出了对几种晶体的测量结果.     

Simulation of silicon diffusion in GaAs

The simulation of coupled diffusion of silicon atoms and point defects in GaAs has been carried out for diffusion at the temperatures of 1000 and 850 °C. The amphoteric behavior of silicon atoms in GaAs has been taken into account in the investigation of high concentration diffusion from silicon layer deposited on GaAs substrate. The calculated dopant profiles agree well with the experimental ones and they confirm the adequacy of the model of silicon diffusion used for simulation. A comparison with the experimental data has enabled this work to obtain the parameters of silicon effective diffusivity and other values describing high concentration silicon diffusion in GaAs.     

在单模光纤中放大的反斯托克斯拉曼背向自发散射的温度效应

在单模光纤中,输入的激光功率大于阈值时．出现放大的反斯托克斯拉曼背向自发散射现象。实验发现：放大的反斯托克斯拉曼背向自发散射具有温度效应．与反斯托克斯拉曼背向自发散射一样,放大的拉曼散射光的光子通量受到光纤温度的调制。反斯托克斯拉曼背向白发散射的放大效应抑制了单模光纤中的相干噪声,改善了系统的信噪比。实验还发现．放大的反斯托克斯扎曼背向自发散射空域曲线上放大的端点位置随激发功率的增高前移并具有一定的规律性。放大的反斯托克斯拉曼背向自发散射的温度效应作为一种新的测温原理,已应用于远程30km分布光纤温度传感器系统。     

He／K系统两步激励产生极紫外相干辐射机制中的斯托克斯及反斯托克斯竞争过程

讨论了Ｈｅ／Ｋ混合蒸汽中两步激励产生极紫外（ＸＵＶ）相干辐射机制中存在的斯托克斯及反斯托克斯跃迁过程．计算了有关跃迁的振子强度、极紫外辐射过程及其竞争过程的受激拉曼散射增益系数和阈值．结果表明，其中６４．３ｎｍ极紫外相干辐射的产生过程与其竞争过程相比，具有最大的增益及最小的阈值；但到能级Ｋ［３ｐ５４ｓ２２Ｐ１／２，３／２］的反斯托克斯跃迁及到能级Ｋ［３ｐ５３ｄ（３Ｐ）４ｓ２２Ｐ１／２，３／２］的斯托克斯跃迁将对其中５９．８ｎｍ极紫外相干辐射的产生构成严重竞争．