直拉硅单晶原生微缺陷的观察

对沿<100>方向生长的p型和沿<111>方向生长的n型宏观无位错直拉硅单晶,用铜缀饰X射线形貌术和腐蚀法观察到两种不同类型的微缺陷,对n型硅单晶还观察到一种特殊组态的微缺陷。对观察到的微缺陷的分布、组态进行了初步的分析。本文首次采用X射线透射投影和截面形貌术对硅单晶原生微缺陷进行直接观察,获得了相应的微缺陷图。所观察到的微缺陷的组态、尺度、分布等与铜缀饰X射线透射形貌图所示结果一致。 关键词：     

硅单晶中片状沉淀物X射线形貌研究

本文利用X射线截面形貌术、限区形貌术、回摆形貌术以及扫描电子显微镜等方法研究了硅单晶中一个片状沉淀物,确定其组态及在晶体内的位置,并对其形成作了简略的分析。 关键词：     

The outlook for X-ray diffraction topography

The possibilities of high-resolution X-ray section topography using the geometry of the interference bands to reveal features of the elastic fields of crystalline lattice defects are considered. The mechanisms of the diffraction of the X-ray wavefield on elastic lattice distortions are demonstrated using the example of dislocations. Microdefects in silicon are another most interesting subject. Section topography is in this case virtually the only method for revealing very weak deformations due to microdefects.     

Diffraction image of screw dislocations in X-ray section topography methods

X-ray diffraction patterns in a thin crystal are investigated by numerical simulation and experimental section topography for the case when the screw dislocation axis is parallel to the dislocation vector. The strongly distorted region near the dislocation core is found to operate like an X-ray mirror wheninteracting with an X-ray wave field in a scattering triangle; i.e., new wave fields appear in the new scattering triangles in the strong distortion region where the crystal departs from the reflecting position, and the coherent interaction of the new fields with the old leads to the formation of a complex X-ray image. Superposition of these waves, taking into account their phases, is found to result in a large variety of defect images.     

合成氟金云母单晶缺陷的X射线研究

本文报道了人工合成大面积氟金云母单晶中缺陷的X射线研究结果。X射线劳厄法的研究表明,在合成云母中存在着较大程度的一维无序,并因而出现许多堆垛错排区及其亚晶界。X射线衍射形貌术的研究表明,合成云母中的亚晶界和位错线大部分是从晶种起源并向生长表面的法线方向延伸的。晶体的靠近表面的区域缺陷较密集,中心部分较少。探讨了合成云母与天然云母中缺陷分布的差别。对用于制作电容器的合成云母片的缺陷与性能的关系作了分析和讨论。 关键词：     

Analysis of contrasts and identifications of Burgers vectors for basal-plane dislocations and threading edge dislocations in 4H-SiC crystals observed by monochromatic synchrotron X-ray topography in grazing-incidence Bragg-case geometry

Contrasts of dislocations in the sub-surface region of the Si-face of a 4H-SiC wafer were observed by monochromatic synchrotron X-ray topography in grazing-incidence Bragg-case geometry. Basal-plane dislocations show very characteristic contrast depending on their Burgers vectors, running directions, and types of dislocations, whether they are screw dislocations, C-core edge dislocations, or Si-core edge dislocations. The rules for contrasts of basal-plane dislocations are summarized. It is shown that by observing those contrasts at fixed diffraction conditions, Burgers vectors of the basal-plane dislocation can be identified without performing a g?·?b analysis in some cases. Threading edge dislocations also have very characteristic contrasts depending on the angles between the projected g and their Burgers vectors. It is shown that Burgers vectors of threading edge dislocations can be determined uniquely by observing their characteristic contrasts without performing g?·?b analysis. Contrast mechanisms for these dislocations in grazing-incidence X-ray topography are discussed.     

天然绿柱石晶体中生长区界面的X射线形貌和光学双折射形貌研究

用X射线形貌术及光学双折射形貌术对天然绿柱石晶体中的生长区界面进行了研究。观测发现,同类生长区的界面在两种形貌中通常不出现可见的衬度;异类生长区界面中,t-s界面在X射线形貌中呈现动力学干涉条纹衬度,表明它们具有平移型界面的特征,根据消光规律知其相应的位移矢量很可能与界面垂直;在双折射形貌中,异类生长区界面衬度的出现与界面两侧存在不同的长程应变场有关。实践表明,两种形貌术互相补充,互相参证,在生长区界面的研究中是十分有效的。 关键词：     

Observation of magnetic domain wall movements by X-ray topography using synchrotron radiation

Antiferromagnetic domain wall movements in KNiF₃ have been observed directly by X-ray topography using synchrotron radiation. Topographs were taken in fields up to 1.3 T at a temperature of 77 K. In contrast to X-ray topography using conventional sources, the apparatus is simple and it is possible to obtain good resolution topographs despite the geometrical limitations imposed by the cryostat and electromagnet. Exposure times were typically 8 seconds when recording on Ilford L4 Nuclear Emulsion plates.     

X-ray topographic imaging of (Al, Ga)N/GaN based electronic device structures on SiC

Structural defects and their impact on the performance, lifetime and reliability of electronic devices are of permanent interest for crystal growers and device manufacturers. This is especially true for epitaxial (Al, Ga)N/GaN based high electron mobility transistor (HEMT) structures on 4H-SiC (0 0 0 1) substrates. This work points out how micropipes, dislocations and grain boundaries present in a 4H-SiC (0 0 0 1) wafer and subsequently overgrown with an (Al, Ga)N-GaN-HEMT layer sequence show up in X-ray topographic images and two-dimensional XRD maps. Using X-ray topography in transmission geometry, micropipes and other structural defects are localized non-destructively below structured metallization layers with a spatial resolution of a few tens of micrometers.     

Light Source for Synchrotron Radiation X-Ray Topography Study at Beijing Syncrotron Radiation Laboratory (BSRL)

Characteristics of the synchrotron radiation source for X-ray topography study at Beijing Synchrotron Radiation Laboratory (BSRL) is desribed in this paper,local geometrical resolution of topographs is discussed,the diffracting intensities of white beam topography is given.     

A study of the contrast on growth striations in silicon by X-ray double crystal topography in the Laue case

The image of growth striations in Si formed by the double crystal X-ray topography in the Laue case (DCTL) is investigated. The results of the dynamical diffraction theory for crystals with small microdefects have been compared with the contrast behaviour determined experimentally. It has been found that the theory explains qualitatively the contrast on the striations and it has been demonstrated that the DCTL method is suitable for detection of the presence of small microdefects in growth striations. Since the paper completes a series of papers on X-ray topography of growth striations, some general conclusions are formulated concerning the applicability of the X-ray topographical methods to the investigation of the structure of the growth striations     

应变弛豫InGaAs/GaAs超晶格的X射线双晶衍射及形貌研究

应用X射线双晶衍射及双晶形貌术,对应变弛豫的InGaAs/GaAs超晶格作了研究,通过对双晶衍射摇摆曲线的计算机模拟,得到了超晶格的结构,应变弛豫机制,弛豫比,超晶格层与衬底的取向差等重要参数。从双晶形貌,得到了超晶格与衬底界面处和超晶格中的位错分布。 关键词：     

BSRF X-Ray Topography Experimental System

This article presents the BSRF white beam topography expeimental system,including a white radiation topography camera,a versatile environmental chamber,an X-ray video imaging system and an image processing facility.The specification of the experimental system and some physical results have heendiscussed.     

High-resolution X-ray topography

X-ray double-crystal topography is, together with section topography, the most deformation-sensitive method. Its advantages and problems are discussed especially in view of the widely spread Lang topography. There are advantages regarding sensitivity, exposure time and the simplicity of contrast evaluation. The disadvantage of its sensitivity to sample warping can be overcome to some extent by a special double-crystal technique with an adaptable bending of the collimator crystal compensating for a homogeneous sample curvature. In contrast to other techniques, double-crystal topography preserves its high-deformation sensitivity also in reflection geometry. That is advantageous if near-surface defects and deformations are investigated as shown by several examples.     

X-ray topography characterization of the structural response of Ge(Ga) crystals to variation in gravity force vector orientation during crystallization

The influence of crystallization process disturbances connected with the variation of the crystallization front orientation relative to the gravity force vector (characteristic for crystal growth under conditions of microgravity onboard space vehicles) on the real crystal structure has been investigated by plane-wave X-ray topography. It has been found that these disturbances can result in a local disorder in the impurity distribution in the form of microsegregation growth striations. Quantitative estimations of the amplitude for the composition variation based on the analysis of contrast in growth striation images obtained by the method of plane-wave X-ray topography have been carried out.     

Visualization of surface acoustic wave scattering by dislocations

Stroboscopic X-ray topography at the synchrotron beam line was used to visualize the propagation of a 580 MHz surface acoustic waves (SAW) in LiNbO3 crystals. For this purpose, the X-ray bursts coming from the synchrotron storage ring with periodicity of 5.68 MHz were synchronized with the SAW frequency in a phase-locked mode. This method allowed us to "stop" the SAW in time and to observe the X-ray diffraction contrast caused by the dynamic deformation field of SAW. The X-ray topographic images showed well-resolved individual acoustic wave fronts of 6 microm SAW as well as their distortions due to SAW scattering by linear dislocations. Some of the images revealed an exceptional contrast of the concentric rings about the dislocation line, which is caused by coherent interaction of the secondary elastic waves. This contrast is similar to the Fresnel zones in optics, and this conclusion is confirmed by direct summation of secondary waves emitted by local elements of a vibrating dislocation string.     

Nd2Fe14B/α-Fe双泪永磁合金快淬带的织构与形貌

利用X射线衍射仪和扫描探针显微镜研究了NeFeB系双相永磁合金快淬带的织构与形貌.结果表明,合金快淬带自由面存在择优取向.与三元NdFeB合金相比,复合添加Dy和Ga具有增加合金快淬带织构和细化组织形貌的作用. 关键词：     

Analysis of dislocation images in X-ray topography of protein crystals: tetragonal hen egg-white lysozyme crystals

Dislocation images in X-ray topography of protein crystals such as tetragonal hen egg-white lysozyme crystals were analyzed. Not only extinction but also double contrast of dislocation images are clearly observed on the X-ray topographs. It should be noted that the observed image widths of the dislocation contrasts are much less than those calculated on the basis of the kinematical theory in X-ray topography, which has been successfully applied for inorganic crystals and organic crystals of small molecules so far. Moreover, in tetragonal HEW lysozyme crystals, the rocking curve widths of the perfect crystal related to the kinematical theory are less than the measured ones by two orders of magnitude. This discrepancy is consistent with that in the image width of the dislocation contrast. From this correlation, it is suggested that the larger rocking curve width, or higher mosaicity, is mainly responsible for the observed image width in the grown crystals.     

X-ray topography of diamond crystals in quasi-forbidden reflections

The X-ray topographs of diamond crystals of different perfection degrees have been obtained using the quasiforbidden 222 reflection. It has been shown that the use of such reflections in X-ray topography makes it possible to study the distribution of the defects affecting the electron density distribution over the crystal cross section.     

同步辐射X射线干涉的实验研究

介绍在北京同步辐射装置上进行的国内首次LLL型X射线干涉实验研究,在X光底片上观察到了Moire干涉条纹,为进一步利用X射线干涉技术实现纳米测量打下了初步基础.