X-ray Nanodiffraction on a Single SiGe Quantum Dot inside a Functioning Field-Effect Transistor

For advanced electronic, optoelectronic, or mechanical nanoscale devices a detailed understanding of their structural properties and in particular the strain state within their active region is of utmost importance. We demonstrate that X-ray nanodiffraction represents an excellent tool to investigate the internal structure of such devices in a nondestructive way by using a focused synchotron X-ray beam with a diameter of 400 nm. We show results on the strain fields in and around a single SiGe island, which serves as stressor for the Si-channel in a fully functioning Si-metal-oxide semiconductor field-effect transistor

The High Data Rate Processing and Analysis Initiative of the Helmholtz Association in Germany

The Helmholtz Association is the largest scientific organization in Germany. It operates all major German research infrastructures involved in research with photons, neutrons, and ions. These are DESY in Hamburg; the Karlsruhe Institute of Technology (KIT); the Research Centre Jülich (FZJ); the Helmholtz Centres in Geesthacht (HZG), Berlin (HZB), and Dresden-Rossendorf (HZDR); and the GSI Centre for research with heavy ions in Darmstadt. In common, all these centers are facing similar challenges related to dramatically increasing data rates and volumes generated with more and more powerful radiation sources together with larger and faster detectors. On the other hand, each center has its own specific portfolio of long-lasting technical expertise in areas like data analysis, information technology, or hardware development. Therefore, it was obvious to address the challenges by acting in concert. This was the main motivation in 2010 for the launch of a joint project among the partners called the “High Data Rate Processing and Analysis Initiative (HDRI).” The initiative is organized into three basic work packages: “Data Management,” “Real-time Data Processing,” and “Data Analysis, Modelling, and Simulation.” The aim is to carry out the development of methods, hardware components, and software for data acquisition, real-time and offline analysis, documentation and archiving, and for remote access to data. The solutions are finally meant to be integrated at the various experimental stations and thus have to be versatile and flexible to cope with the heterogeneous requirements of the different experiments. The claim to create standard solutions makes it mandatory to closely collaborate with large international activities in the field of data handling, like the European PaNdata project (see article in this issue), but also with vendors of detectors, data evaluation software, etc., as well as with corresponding standardization bodies

Core-shell nanowires: From the ensemble to single-wire characterization

Recent investigations of core-shell nanowires using synchrotron radiation techniques deduced the average structural parameters of heterostructure core-shell nanowires. Here, we report on first results and discuss the problems arising when measuring such complex nanostructures by using nanofocusing X-ray techniques. InAs/IAsP core-shell nanowires exhibit a certain bending, the origin of which is described using finite element simulations assuming a displacement of the core, and a gradient in the chemical composition of the wire's shell. (C) 2009 Elsevier B.V. All rights reserved

xrayutilities : a versatile tool for reciprocal space conversion of scattering data recorded with linear and area detectors

We present general algorithms to convert scattering data of linear and area detectors recorded in various scattering geometries to reciprocal space coordinates. The presented algorithms work for any goniometer configuration including popular four-circle, six-circle and kappa goniometers. We avoid the use of commonly employed approximations and therefore provide algorithms which work also for large detectors at small sample detector distances. A recipe for determining the necessary detector parameters including mostly ignored misalignments is given. The algorithms are implemented in a freely available open-source package.Comment: 28 pages, 5 figures, submitted to the Journal of Applied Crystallograph

Structural Investigations of Core-shell Nanowires Using Grazing Incidence X-ray Diffraction.

The fabrication of core-shell structures is crucial for many nanowire device concepts. For the proper tailoring of their electronic properties, control of structural parameters such as shape, size, diameter of core and shell, their chemical composition, and information on their strain fields is mandatory. Using synchrotron X-ray diffraction studies and finite element simulations, we determined the chemical composition, dimensions, and strain distribution for series of InAs/InAsP core-shell wires grown on Si(111) with systematically varied growth parameters. In particular we detect initiation of plastic relaxation of these structures with increasing shell thickness and/or increasing phosphorus content. We establish a phase diagram, defining the region of parameters leading to pseudomorphic nanowire growth. This is important to avoid extended defects which are detrimental for their electronic properties

The NeXus data format

NeXus is an effort by an international group of scientists to define a common data exchange and archival format for neutron, X-ray and muon experiments. NeXus is built on top of the scientific data format HDF5 and adds domain-specific rules for organizing data within HDF5 files, in addition to a dictionary of well defined domain-specific field names. The NeXus data format has two purposes. First, it defines a format that can serve as a container for all relevant data associated with a beamline. This is a very important use case. Second, it defines standards in the form of application definitions for the exchange of data between applications. NeXus provides structures for raw experimental data as well as for processed data