Application of kinoform lens for X-ray reflectivity analysis

Recent Progresses in Nanometer Scale Analysis of Buried Layers and Interfaces in Thin Films by X-rays and Neutrons

In the early 1960s, scientists achieved the breakthroughs in the fields of solid surfaces and artificial layered structures. The advancement of surface science has been supported by the advent of ultra-high vacuum technologies, newly discovered and established scanning probe microscopy with atomic resolution, as well as some other advanced surface-sensitive spectroscopy and microscopy. On the other hand, it has been well recognized that a number of functions are related to the structures of the interfaces, which are the thin planes connecting different materials, most likely by layering thin films. Despite the scientific significance, so far, research on such buried layers and interfaces has been limited, because the probing depth of almost all existing sophisticated analytical methods is limited to the top surface. The present article describes the recent progress in the nanometer scale analysis of buried layers and interfaces, particularly by using X-rays and neutrons. The methods are essentially promising to non-destructively probe such buried structures in thin films. The latest scientific research has been reviewed, and includes applications to bio-chemical, organic, electronic, magnetic, spintronic, self-organizing and complicated systems as well as buried liquid-liquid and solid-liquid interfaces. Some emerging analytical techniques and instruments, which provide new attractive features such as imaging and real time analysis, are also discussed.

Non-destructive imaging of buried electronic interfaces using a decelerated scanning electron beam

Recent progress in nanotechnology enables the production of atomically abrupt interfaces in multilayered junctions, allowing for an increase in the number of transistors in a processor. However, uniform electron transport has not yet been achieved across the entire interfacial area in junctions due to the existence of local defects, causing local heating and reduction in transport efficiency. To date, junction uniformity has been predominantly assessed by cross-sectional transmission electron microscopy, which requires slicing and milling processes that can potentially introduce additional damage and deformation. It is therefore essential to develop an alternative non-destructive method. Here we show a non-destructive technique using scanning electron microscopy to map buried junction properties. By controlling the electron-beam energy, we demonstrate the contrast imaging of local junction resistances at a controlled depth. This technique can be applied to any buried junctions, from conventional semiconductor and metal devices to organic devices.

Sub-500 nm hard x ray focusing by compound long kinoform lenses

The focusing performance of polymethyl methacrylate compound long kinoform lenses with 70 μm aperture and 19.5 mm focal length was characterized with 8 keV x rays using the knife-edge scan method at the 4W1A transmission x-ray microscope beamline of Beijing Synchrotron Radiation Facility. The experiment result shows a best FWHM focus size of 440 nm with 31% diffraction efficiency.

A microfocus X-ray fluorescence beamline at Indus-2 synchrotron radiation facility

A microfocus X-ray fluorescence spectroscopy beamline (BL-16) at the Indian synchrotron radiation facility Indus-2 has been constructed with an experimental emphasis on environmental, archaeological, biomedical and material science applications involving heavy metal speciation and their localization. The beamline offers a combination of different analytical probes, e.g. X-ray fluorescence mapping, X-ray microspectroscopy and total-external-reflection fluorescence characterization. The beamline is installed on a bending-magnet source with a working X-ray energy range of 4-20 keV, enabling it to excite K-edges of all elements from S to Nb and L-edges from Ag to U. The optics of the beamline comprises of a double-crystal monochromator with Si(111) symmetric and asymmetric crystals and a pair of Kirkpatrick-Baez focusing mirrors. This paper describes the performance of the beamline and its capabilities with examples of measured results.

High efficiency nano-focusing kinoform optics for synchrotron radiation

Modern synchrotron sources have provided for decades intense beams of photons over a large energy spectrum. The availability of improved optics and detectors has opened up new opportunities for the study of matter at the micrometre and nanometre scale in many disciplines. Whilst exploitation of micro-focused beams occurs almost daily in many beamlines, the production of beams of 100 nm is achieved on few instruments which use specialised optics. Refractive lenses, zone plates, curved mirrors, multilayers, and multilayer Laue lenses, can all focus x-rays to less than 50 nm under strict beam stability conditions. Focusing the synchrotron radiation to beam sizes smaller than 10 nm is considered the ultimate goal for the current decade. Silicon micro-technology has so far provided some of the most advanced x-ray refractive lenses; we report on design and characterisation of a novel silicon kinoform lens that is capable of delivering nano-beams with high efficiency.