Applying%20X-Rays%20in%20Material%20Analysis

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Applying X-Rays in Material Analysis

• Vladimir Kogan
• Philips Analytical and DANNALAB
• The Netherlands

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X-Ray Diffraction Analysis

• Based on measuring the intensity of the x-rays
  diffracted by the sample at different angles
• Delivers information about the structure and
  composition of material at different scales
• This information is used to explain or predict
  the properties of a sample

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Classification of Samples

• Amorphous
• Polycrystalline
• Monocrystalline

Bulks Powders and Foams Thin Films
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XRD for Amorphous Materials
SAXS Analysis of Human Serum Albumin (HSA)in the
Monodisperse Solution and in the Native Serum
An understanding of the structural properties of
serum albumin is extremely important in the
development of new human pharmaceuticals. HSA
contributes to many transport and regulatory
processes in the body. Distribution, free
concentration and metabolism of verious
pharmaceuticals can be significantly influenced
depending from the binding with HSA.
From the monodisperse curve of HSA we have
determined the average parameters of the molecule
- axes of ellipsoid, suface, volume, radius of
gyration etc. From the polydisperse curve (native
serum) we have derived the histogram of particles
distribution by average radius.
DANNALAB, 2002
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XRD for Polycrystalline Materials

• Crystallography - type and dimensions of unit
  cell
• Atomic structure - atoms coordinates
• Grains size and shape
• Micro and macro strain
• Phase composition - presence and concentration of
  different phases

D-Mannitol (beta form) HOCH2(CHOH)4CH2OH
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Si Detector for XRD Applications

• 0.07mm pitch
• No cooling required
• Efficiency gt 94 for 8KeV
• Maximum 4mln cps in the complete detector
• Background lt 0.1 cps

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Specific of Thin Layers
ct gt aL at aS
ct
Strained layer
Relaxed layer
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Pseudomorphic epitaxial layers. No defects.
Strain may be present Example AlGaAs/GaAs,
SiGe/Si Applications Lasers, High-frequency
ICs Lattice mismatched epitaxial layers.
Layers are partly (or fully) relaxed Example
ZnSe/GaAs, InAsSb/GaSb Applications Blue
LEDs, IR optopelectronic Layers with large
lattice mismatch and/or dissimilar crystal
structures Example GaN/Sapphire, YBaCuO/SrTiO3,
BST, PZT Applications Blue Lasers and LEDs,
High Tc Superconductors, Ferro electrics
Layers where the epitaxial relationship is weak.
Highly textured. Example AuCo multilayers on
Si Applications Thin film media, heads
Different Types of Thin Films
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XRD for Thin Films and Layers

• Reflectivity Measurements
• Thickness, Density, Surface Roughness
• Lateral and Depth Correlation
• Curvature

• In-plane Scattering
• Nano-layers
• Nano-structures
• In-plane properties

• High Resolution Diffraction
• Orientation
• Quality of Epitaxy, Lattice Mismatch
• Phase Composition
• Thickness, Density, Surface Roughness

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Typical Setup for Reflectivity Measurements
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The Information that can be Derived from a
Reflectivity Curve
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Reflectivity
XRD Study of Self-Assembled Monolayers C18H37SH
on Gold
Specular Reflectivity Curve
Reflectivity Map, Diffuse Scattering
Determined thickness of the layers C18H37SH -
1.6nm Au1 - 0.6nm Au2 - 19.0nm Si gt 100000nm
Determined Average Lateral Correlation Length
2.5nm
DANNALAB, 2002
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Modern High Resolution Diffractometer
The highly parallel monochromatic beam should be
used to study perfect layers
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High Resolution Diffraction
Analysis of SiGe HBT Structure The introduction
of a SiGe epitaxial layer in the bipolar
transistor (HBT) brings significant gains in
speed, challenging GaAs in its traditional
application fields. New technological step of
introducing Ge requires also an accurate method
for the characterization of Ge content and
gradients.
Automatic simulation and refinement of a measured
rocking curve helps to identify parameters of
individual layers. Method delivers 1 accuracy
for composition and 3 accuracy for SiGe
thickness.
DANNALAB, 2002
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High Resolution Diffraction GaN/InGaN (Blue
Laser Structure)
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Reciprocal Space Map
Relaxed GaInAs/GaAs (224)
S
L
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Orientation and Domain Structure
Transition in YBa2Cu3O8-x Film on SrTiO3
Substrate XRD Measurements 304 Reciprocal Space
Maps
20nm tetragonal (nonsuperconducting) phase
100nm orthorhombic (superconducting) phase
With the increase of the thickness of the
YBa2Cu3O8-x layer, the dependence of the
structure from the SrTiO3 substrate is declining.
This results in the appearance of the
orthorhombic superconducting phase.
DANNALAB, 2002
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High Resolution Diffraction
Strain Fields in Boron-implanted Silicon
DANNALAB, 2002
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Devices and Structures
Stresses due to adhesive bonding Different
methods has been tested to make stress-free
bonding of Si with steel. One of the methods (s41
and s42) delivers quality, comparable with the
stress free samples (Test1 and Test2)
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IC Chip Glued on the Ceramic Substrate
Surface Mapping by Measuring Rocking Curves
Method 1
Method 2
DANNALAB, 2002
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Sensor on Chip Assembly
Surface Mapping by Measuring Rocking Curves
Mapping of free standing Si sensor
Mapping of sensor bump-bonded to chip
DANNALAB, 2002
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Roadmaps for new XRD detectors
Polycrystalline Materials
Monocrystalline Materials
Amorphous Materials

• 0D, 1D and 2D
• Different shapes
• Very low noise
• Pixel size down to 0.05 mm
• Counting speed upto 105c/s/mm2
• Energy resolution lt250 eV

• 0D, 1D and 2D
• Flat shape
• Dynamical range 107
• Counting speed up
• to 107c/s/mm2 useful energy and 109 total
• Energy resolution lt250 eV

• 0D, 2D
• Flat shape
• Dynamical range 107
• Counting speed upto the 107c/s/mm2

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Conclusions

• Appearance of new technologies for x-ray
  detectors considered to be one of the key factors
  for the advances in XRD instrumentation.
• The applications of XRD actively shifting
  nowadays to the field of high-tech materials an
  devices, including advanced x-ray detectors.
• Both fields have a lot of synergy and may benefit
  from each other.
• Special thanks to
• J. Visschers, for inviting me to this conference
• J. Woitok, M. Fransen, K. Bethke, R. de Vries for
  useful comments