金属有机化学汽相沉积生长InGaN薄膜的研究

以Al2O3为衬底,采用金属有机汽相沉积（MOCVD）技术在GaN膜上生长了InxGa1-xN薄膜。以卢瑟福背散射／沟道技术和光致发光技术对InxGa1-xN／GaN/Al2O3样品进行了分析,研究表明,金属有机汽相沉积生长高In组分InxGa1-xN薄膜有一最佳TMIn/TEGa摩尔流量比。在一定范围内,降低其摩尔流量比,合金的生长速率增高,In组分提高;进一步降低TMIn/TEGa摩尔流量比,导致In组分下降,研究还表明,InGan薄膜的结晶品质随In组分的增大而下降,InGan薄膜的In组分由0．04增大到0．10,其最低沟道产额比由4．1％增至11．0％。     

Lattice Location Studies of Indium in Cr2O3

The lattice sites of implanted In atoms in Cr₂O₃ were investigated by means of electron emission channeling (EC) measurements using ¹¹¹In probe atoms. EC spectra were recorded for several axes and compared to simulations. Indium atoms are most likely located at near-Cr sites. Small differences in the EC patterns for prompt and delayed electrons may be an indication for displacements of ¹¹¹Cd emitter atoms following the electron capture decay of In. This revised version was published online in September 2006 with corrections to the Cover Date.     

白光彩色联合变换相关实验中的分通道方法

提出了在彩色联合变换相关中, 使用光栅对彩色图像进行分通道处理的方法, 讨论了实现此方法对光源、滤色片的限制, 并基于此讨论提出了一种使用三色光栅图像编码的分通道解决方法。实验的结果表明, 这种方法不但降低了对光源的限制, 而且对取向不同的功率谱也便于进行分通道并行处理, 包括并行地使用零级功率谱进行彩色图像的仅形状相关。     

Determination of the crystallographic parameters of a fcc metal by means of electron channelling patterns

Indexing and mapping of selected area electron channelling patterns (SAECPs) of an Al‐Zn‐Mg alloy have been performed. Although, channelling patterns are similar for crystals having the same system, since the interplanar spacing and the angular band width depend on lattice parameter, the details of the map will differ for every material. Angles between the poles and the angular separations of channelling bands were measured on the micrographs and calculated with the well known equations and found to be well in agreement within the error limits. Also the channelling line widths were calculated with the help of extinction distances of the reflecting planes. Structure factors and atomic scattering factors for selected reflections were also calculated for the present alloy whose a = 4.054 Å.     

Study of fission fragments channeling in silicon monocrystals

Abstract

The research results of ²³⁵U fission fragments channeling in silicon semiconductor detectors of heavy ions are reported. The analysis of the pulse height defect enabled to obtain the experimental relationship between energy losses in silicon due to nuclear collisions and the energy of fission fragments in LSS-units. The experimental values obtained more than twice exceed the computed ones given by Heines and Whitehead based on Lindhard's theory.     

Binary encounter electron spectroscopy under channeling incidence conditions

Abstract

This paper briefly reviews fundamental and applied aspects of our recent study of binary encounter electrons induced by MeV/amu ions. The binary encounter electron spectroscopy (BEES) under channeling incidence conditions enables precise measurements of the ion-beam shadowing effect, providing unique information on ion-solid interactions.     

Electromagnetic radiation of MeV electrons in thick aligned single crystals

Abstract

Earlier published theoretical models for MeV electrons are generalized in this paper. Different theoretical predictions for planar channeling and accompanying electromagnetic radiation in thick crystals are presented. A comparative analysis of theoretical and experimental spectra of photon radiation is given. Thickness dependences of channeling quantum state populations, radiation line broadening and photon flux intensities are obtained. The existence of planar electron channeling at 54 MeV in a silicon single crystal with a thickness of several millimetres is shown.     

Crystalline to amorphous transformations in ion implanted GaP

Abstract

The amorphization process of GaP by ion implantation is studied. The samples of 〈111〉 oriented GaP were implanted at 130 K with various doses 5 × 10¹³-2 × 10¹⁶ cm^?2 of 150 keV N⁺ ions and with the doses of 6 × 10¹²-1.5 × 10¹⁵ cm^?2 of 150 keV Cd⁺ ions. Room temperature implantations were also performed to see the influence of temperature on defect production. Rutherford backscattering and channelling techniques were used to determine damage in crystals. The damage distributions calculated from the RBS spectra have been compared with the results of Monte-Carlo simulation of the defect creation.

The estimated threshold damage density appeared to be independent on ion mass and is equal 6.5 × 10²⁰ keV/cm³. It is suggested that amorphization of GaP is well explained on the basis of a homogenous model.     

The effect of incidence angle on disorder production in ion implanted Si

Abstract

Ne, Ar, Sb, and Xe ions have been implanted, at 30 keV or 80 keV and at various incidence angles, into Si substrates maintained at room temperature during implantation. Implantation-induced Si disorder was measured using RBS-channelling. The effects upon disorder of various incidence angles were studied over a fluence range of 10¹²-10¹⁶ ions·cm^?2.

The results show that, at low fluences the lighter (Ne) and slightly heavier (Ar) ion implantations generate a bimodal disorder-depth profile, whilst at higher fluences measurements of amorphised layer thickness as a function of ion incidence angle allow values of the standard deviation of the disorder profile parallel and transverse to the ion beam direction for each ion to be obtained with good agreement to theoretical predictions.     

Synchrotron‐based spectroscopy of X‐ray channeling through hollow capillary microchannels inside glass plates

Here, soft X‐ray synchrotron radiation transmitted through microchannel plates is studied experimentally. Fine structures of reflection and XANES Si L‐edge spectra detected on the exit of silicon glass microcapillary structures under conditions of total X‐ray reflection are presented and analyzed. The phenomenon of the interaction of channeling radiation with unoccupied electronic states and propagation of X‐ray fluorescence excited in the microchannels is revealed. Investigations of the interaction of monochromatic radiation with the inner‐shell capillary surface and propagation of fluorescence radiation through hollow glass capillary waveguides contribute to the development of novel X‐ray focusing devices in the future.