Fast acquisition of extensive X-ray diffraction patterns of a gas–liquid interface in grazing-incidence geometry

The development of third-generation synchrotron sources has inspired qualitative and quantitative breakthroughs in structural studies of monomolecular organic layers. To study such systems formed at the gas–liquid interface, grazing-incidence diffraction (GID) has proved to be the most powerful technique. Until quite recently, in most cases, GID was performedviaa scanning approach with use of a collimating system in front of the detector to eliminate the effect of parallax and to achieve the required angular resolution. Owing to the long counting time required, this kind of measurement often introduces significant radiation damage to a sample and considerably restricts time-resolved studies, preventing the pursuit of emerging scientific areas such as the investigation of fast kinetic structural changes in two-dimensional systems. This problem can apparently become a real obstacle for the application of the scanning GID technique at fourth-generation synchrotron sources because of the extremely high X-ray fluxes involved. This article discusses the possibility of significantly reducing the measuring time and avoiding the beam parallax problem by using a high-brilliance submillimetre beam and a large-area two-dimensional detector (e.g.PILATUS) in a single-shot GID measurement on large-area sample surfaces. Both theoretical considerations of the problem and experimental GID results from monomolecular layers of behenic acid at the gas–water interface are presented, with a detailed description of the experimental conditions. The possibility of a diffraction imaging study of the texture of Langmuir monomolecular layers is demonstrated.

Download Full-text

Structure of Magnetically Ordered Si:Mn

Solid State Phenomena ◽

10.4028/www.scientific.net/ssp.131-133.327 ◽

2007 ◽

Vol 131-133 ◽

pp. 327-332 ◽

Cited By ~ 1

Author(s):

Jadwiga Bak-Misiuk ◽

Elżbieta Dynowska ◽

Przemyslaw Romanowski ◽

A. Shalimov ◽

Andrzej Misiuk ◽

...

Keyword(s):

Structural Changes ◽

Crystalline Silicon ◽

Reciprocal Lattice ◽

Grazing Incidence ◽

Processing Parameters ◽

Incidence Geometry ◽

Geometry Processing ◽

Reciprocal Lattice Point ◽

X Ray ◽

Disturbed Layer

The structure studies of single crystalline silicon implanted at 340 K or 610 K with Mn+ ions (Si:Mn) and subsequently processed under atmospheric and enhanced hydrostatic pressure at up to 1270 K are reported. The defect structure was determined by an analysis of X-ray diffuse scattering around the 004 reciprocal lattice point and by electron microscopy. High resolution X-ray diffraction techniques based on the conventional source of radiation were used for this purpose. The crystal structure of Si:Mn and the Si1-xMnx precipitates in the implantation – disturbed layer were studied by synchrotron radiation diffraction in the grazing incidence geometry. Processing of Si:Mn results in crystallization of amorphous Si within the buried implantation – disturbed layer and in formation of Mn4Si7 precipitates. Structural changes are dependent both on temperature of the Si substrate at implantation and on processing parameters.

Download Full-text

Resolution extension by image summing in serial femtosecond crystallography of two-dimensional membrane-protein crystals

IUCrJ ◽

10.1107/s2052252517017043 ◽

2018 ◽

Vol 5 (1) ◽

pp. 103-117 ◽

Cited By ~ 7

Author(s):

Cecilia M. Casadei ◽

Ching-Ju Tsai ◽

Anton Barty ◽

Mark S. Hunter ◽

Nadia A. Zatsepin ◽

...

Keyword(s):

Membrane Protein ◽

Large Scale ◽

Structural Changes ◽

Signal To Noise Ratio ◽

Three Dimensional ◽

Single Layer ◽

Protein Crystals ◽

Single Shot ◽

Two Dimensional ◽

X Ray

Previous proof-of-concept measurements on single-layer two-dimensional membrane-protein crystals performed at X-ray free-electron lasers (FELs) have demonstrated that the collection of meaningful diffraction patterns, which is not possible at synchrotrons because of radiation-damage issues, is feasible. Here, the results obtained from the analysis of a thousand single-shot, room-temperature X-ray FEL diffraction images from two-dimensional crystals of a bacteriorhodopsin mutant are reported in detail. The high redundancy in the measurements boosts the intensity signal-to-noise ratio, so that the values of the diffracted intensities can be reliably determined down to the detector-edge resolution of 4 Å. The results show that two-dimensional serial crystallography at X-ray FELs is a suitable method to study membrane proteins to near-atomic length scales at ambient temperature. The method presented here can be extended to pump–probe studies of optically triggered structural changes on submillisecond timescales in two-dimensional crystals, which allow functionally relevant large-scale motions that may be quenched in three-dimensional crystals.

Download Full-text

Synchrotron X-Ray Topography Study on the Relationship between Local Basal Plane Bending and Basal Plane Dislocations in PVT-Grown 4H-SiC Substrate Wafers

Materials Science Forum ◽

10.4028/www.scientific.net/msf.1004.393 ◽

2020 ◽

Vol 1004 ◽

pp. 393-400

Author(s):

Tuerxun Ailihumaer ◽

Hongyu Peng ◽

Balaji Raghothamachar ◽

Michael Dudley ◽

Gilyong Chung ◽

...

Keyword(s):

Basal Plane ◽

Local Strain ◽

Grazing Incidence ◽

Peak Shift ◽

Linear Mapping ◽

Incidence Geometry ◽

Convex Shape ◽

X Ray ◽

Black And White ◽

Plane Bending

Synchrotron monochromatic beam X-ray topography (SMBXT) in grazing incidence geometry shows black and white contrast for basal plane dislocations (BPDs) with Burgers vectors of opposite signs as demonstrated using ray tracing simulations. The inhomogeneous distribution of these dislocations is associated with the concave/convex shape of the basal plane. Therefore, the distribution of these two BPD types were examined for several 6-inch diameter 4H-SiC substrates and the net BPD density distribution was used for evaluating the nature and magnitude of basal plane bending in these wafers. Results show different bending behaviors along the two radial directions - [110] and [100] directions, indicating the existence of non-isotropic bending. Linear mapping of the peak shift of the 0008 reflection along the two directions was carried out using HRXRD to correlate with the results from the SMBXT measurements. Basal-plane-tilt angle calculated using the net BPD density derived from SMBXT shows a good correlation with those obtained from HRXRD measurements, which further confirmed that bending in basal plane is caused by the non-uniform distribution of BPDs. Regions of severe bending were found to be associated with both large tilt angles (95% black contrast BPDs to 5% white contrast BPDs) and abrupt changes in a and c lattice parameters i.e. local strain.

Download Full-text

Correlation Between the V-I Characteristics of (0001) 4H-SiC PN Junctions Having Different Structural Features and Synchrotron X-ray Topography

MRS Proceedings ◽

10.1557/proc-1069-d07-21 ◽

2008 ◽

Vol 1069 ◽

Author(s):

Ryoji Kosugi ◽

Toyokazu Sakata ◽

Yuuki Sakuma ◽

Tsutomu Yatsuo ◽

Hirofumi Matsuhata ◽

...

Keyword(s):

High Energy ◽

Structural Features ◽

Incidence Geometry ◽

Voltage Source ◽

Large Area ◽

Chip Area ◽

Power Mosfets ◽

X Ray ◽

Pn Junctions ◽

The Difference

ABSTRACTIn practical use of the SiC power MOSFETs, further reduction of the channel resistance, high stability under harsh environments, and also, high product yield of large area devices are indispensable. Pn diodes with large chip area have been already reported with high fabrication yield, however, there is few reports in terms of the power MOSFETs. To clarify the difference between the simple pn diodes and power MOSFETs, we have fabricated four pn-type junction TEGs having the different structural features. Those pn junctions are close to the similar structure of DIMOS (Double-implanted MOS) step-by-step from the simple pn diodes. We have surveyed the V-I characteristics dependence on each structural features over the 2inch wafer. Before their fabrication, we formed grid patterns with numbering over the 2inch wafer, then performed the synchrotron x-ray topography observation. This enables the direct comparison the electrical and spectrographic characteristics of each pn junctions with the fingerprints of defects.Four structural features from TypeA to TypeD are as follows. TypeA is the most simple structure as same as the standard pn diodes formed by Al+ ion implantation (I/I), except that the Al+ I/I condition conforms to that of the p-well I/I in the DIMOS. The JTE structure was used for the edge termination on all junctions. While the TypeA consists of one p-type region, TypeB and TypeC consists of a lot of p-wells. The difference of Type B and C is a difference of the oxide between the adjacent p-wells. The oxide of TypeB consists of the thick field oxide, while that of TypeC consists of the thermal oxide corresponding to the gate oxide in the DIMOS. In the TypeD structure, n+ region corresponding to the source in the DIMOS was added by the P+ I/I. The TypeD is the same structure of the DIMOS, except that the gate and source contacts are shorted. The V-I measurements of the pn junctions are performed using the KEITHLEY 237 voltage source meters with semi-auto probe machine. An active area of the fabricated pn junctions TEGs are 150um2 and 1mm2. Concentration and thickness of the drift layer are 1e16cm−3 and 10um, respectively.In order to compare the V-I characteristics of fabricated pn junctions with their defects information that obtained from x-ray topography measurements directly, the grid patterns are formed before the fabrication. The grid patterns were formed over the 2inch wafer by the SiC etching. The synchrotron x-ray topography measurements are carried out at the Beam-Line 15C in Photon-Factory in High-Energy-Accelerator-Research-Organization. Three diffraction conditions, g=11-28, -1-128, and 1-108, are chosen in grazing-incidence geometry (improved Berg-Barrett method).In the presentation, the V-I characteristics mapping on the 2inch wafer for each pn junctions, and the comparison of V-I characteristics with x-ray topography will be reported.

Download Full-text