半导体中掺杂是控制半导体的光电性能的手段,杂质在半导体中的浓度和分布等结构参数与材料的物理性质直接相关。随着分子束外延等材料生长技术的发展,新型的半导体材料如超晶格已经广泛地吸引了人们的注意。δ掺杂是近年来国际上出现的又一种新的结构,它可减少二维电子(空穴)气系统中的杂质离子散射,在科学和技术应用上都有重要意义。 δ掺杂样品中的杂质离子仅分布在几个纳米的尺度内,一些常用的结构成分分析方法难以进行检测。如Rutherford背散射(RBS)、中能离子散射(MEIS)只对浓度原子百分比大于10~(-2)％杂质敏感,而二次离子质谱(SIMS)的空间分辨一般为3μm左右。X射线是检测物质结构的有效方法,常规光源的强度不足以测量到足够的衍射振荡来分析δ掺杂的结构。同步辐射光源是高亮度的X射线光源,它已成功地用来测量δ掺杂的结构。 北京同步辐射装置漫散射实验站所用光源来自4W1C光束线,X光经一块压弯的三角形硅单晶单色化并水平聚焦后,再由一块全反射柱面镜进行垂直聚焦和滤去高次谐波,在样品处得到光斑大小为0.3mm×0.5mm、垂直发散度为0.1m rad的单色光。本实验中,三角弯晶为Si(111),所得的单色光波长为0.154nm。衍射平面在垂直方向,以利用同步光的水平偏振和垂直发散度小的特点。样品和探测器 Doping in semiconductors is a means of controlling the optoelectronic properties of semiconductors. The structural parameters such as concentration and distribution of impurities in semiconductors are directly related to the physical properties of the material. With the development of material growth technologies such as molecular beam epitaxy, new types of semiconductor materials such as superlattices have attracted the attention of a wide range of people. δ doping is a new kind of new structure appearing in the world in recent years. It can reduce impurity ion scattering in two-dimensional electron (hole) gas system and is of great significance in the application of science and technology. Impurity ions in δ-doped samples are distributed only on the scale of a few nanometers, and some commonly used methods for analyzing structural components are difficult to detect. For Rutherford backscattering (RBS), MEIS is only sensitive to impurities with concentration greater than 10 ~ (-2)%, whereas spatial resolution of SIMS is generally about 3μm. X-ray is an effective method to detect the structure of matter. The intensity of conventional light source is not enough to measure enough diffraction oscillation to analyze δ-doped structure. Synchrotron radiation sources are high-brightness x-ray sources that have been used successfully to measure δ-doped structures. Beijing Synchrotron Radiation Facility The diffuse scattering experiment station uses a light source from the 4W1C beamline. The X-ray is monochromatized by a curved triangular silicon monocrystal and focused horizontally. A total reflection cylinder mirror then focuses vertically and filters out high-order Harmonic, monochromatic light having a spot size of 0.3 mm × 0.5 mm and a vertical divergence of 0.1 m rad was obtained at the sample. In this experiment, triangular bends are Si (111), and the resulting monochromatic light has a wavelength of 0.154 nm. The diffraction plane is in the vertical direction to take advantage of the small horizontal polarization and vertical divergence of the synchrotron light. Samples and detectors