High Resolution X-Ray Diffractometer

申请的衍射仪将主要用于薄膜系统和半导体异质结构的高分辨率x射线衍射，这些薄膜系统和半导体异质结构是由申请人（Prof. Dr. Reuter, Prof. Dr. D.J. As和Prof. Dr. C. Meier）通过分子束外延制造的。在材料方面，重点是不同的半导体，如GaAs/(Al,Ga)As，立方GaN/(Al,Ga)N和ZnO/(Zn,Mg)O。为了获得高质量的异质结构，材料的结构表征是至关重要的。分子束外延是一种复杂的方法，其中许多实验参数，如衬底温度，单个元素的分子通量，在某些情况下气体通量和等离子体功率，残余气体压力和样品支架内的热传导等等，决定了制备异质结构的质量。为了达到生长层的最佳质量，必须进行仔细的结构表征-在理想情况下，在生长后直接进行。这种结构表征不仅涉及异质结构本身（化学计量和层厚度以及粗糙度），而且还涉及缺陷和不需要的三维或多晶生长。x射线衍射在半导体异质结构领域的核心应用是高分辨率x射线衍射的经典方法，特别是用于研究应变和弛豫、伪晶生长以及超晶格和界面的互易空间图。由于在申请人群体中产生的大量样品对互易空间地图测量的高要求，有效利用测量时间是很重要的，为什么系统应该允许自动调整和自动化测量过程。此外，x射线反射法（XRR）和掠入射衍射法（GID）应该可以用于研究最薄的薄膜。另一个应用领域是研究用不同光刻方法制造的纳米材料（AG J. Lindner）。对于这些异质结构的分析，将采用Bragg-Brentano几何中的经典粉末衍射方法

The applied-for diffractometer will mainly be employed for high resolution X-ray diffraction of thin film systems and semiconductor heterostructures, which are fabricated in the groups of the applicants (Prof. Dr. D. Reuter, Prof. Dr. D.J. As und Prof. Dr. C. Meier) via molecular beam epitaxy. Concerning the materials, the focus is on different semiconductors, for example GaAs/(Al,Ga)As, cubic GaN/(Al,Ga)N and ZnO/(Zn,Mg)O. For the growth of highest quality heterostructures, the structural characterization of the materials is of paramount importance. Molecular beam epitaxy is a complex method, where numerous experimental parameters, as substrate temperature, molecular fluxes of individual elements, in some cases gas fluxes and plasma power, residual gas pressure and thermal conduction within the sample holder and many more, determine the quality of the fabricated heterostructures. To achieve the optimum quality of the grown layers, a careful structural characterization has to be performed - in an ideal case directly after growth. This structural characterization addresses not only the heterostructure itself (stoichiometry and layer thicknesses as well as roughness) but also the presence of defects and unwanted three-dimensional or polycrystalline growth.Core applications for X-ray diffraction in the area of semiconductor heterostructures are classical methods of high-resolution X-ray diffraction and especially reciprocal space maps to investigate strain and relaxation, pseudomorphic growth as well as superlattices and interfaces. Due to the high demand of reciprocal space map measurements related to the high number of samples produced in the groups of the applicants an effective use of the measurement time is important, why the system should allow for auto-adjustment and automatization of measurement processes. In addition, X-ray reflectometry (XRR) and diffraction under grazing incidence (GID) should be possible for the investigation of thinnest films.Another application area is the investigation of nanomaterials fabricated with different lithography methods (AG J. Lindner). For the analysis of those heterostructure, the methods of classical powder diffractometry in Bragg-Brentano geometry will be employed