9. Why use GIXRD?
Total
reflection
regime
Absorption
limited
regime
0 0.5 1.0 1.5
/c
1
10
10
0
100
0
Z0(nm)
o By changing the
incidence angle the x-
ray penetration depth
into the samples can be
changed
o GIXRD provides
surface information or
depth profiling on
randomly oriented
polycrystalline materials
X-ray penetration depth
9
10. Grazing incidence Application Areas
Task or challenges Solution
Weak signal from ultra thin films GIXRD geometry increases layer signal
Overlapping peaks GIXRD helps distinguish thin film signal from
substrate or other layers
Strain/Stress measurement Via GIXRD residual stress can be measured
as a function of depth
Phase ID Via GIXRD phase ID analysis can be done at
the surface and can be done as a function of
depth
Dealing with Textures Samples For Rietveld refinement, size-strain analysis,
unit cell refinement the GIXRD geometry gets
signal typically from the random oriented
grains in the sample
10
11. GIXRD Configuration
Incident beam optics:
o fixed or
programmable
divergent and anti-
scattering slits
o X-Ray Parabolic
Mirror
Diffracted beam optics:
o fixed or
programmable
receiving and anti-
scattering slits
o X-Ray Parabolic
Mirror
o Parallel Plate
Collimator (0.270,
0.180, 0.090, )
11
13. GIXRD for CIGS Solar Cells
W.K. Kim et al. / Journal of Crystal Growth 294 (2006) 231–235
Comparison of GIXRD
scan versus conventional
symmetrical scan.
In the symmetrical scan
a large portion of the
diffractogram comes from
the substrate, the
diffraction peaks of the
thin film are barely visible.
In the GIXRD scan the
diffraction peaks of the
thin film are enhanced.
13
17. Example 2 - Surface treatment effect
• Austenitic stainless steels cannot be hardened
by heat treatment
• Colossal Carbon Super-saturation Process is
one way to harden the austenitic steel:
– Carbon diffuses into the steel at elevated to create
compressive residual stress
– As the sample cools down some C is released at
very top surface (few nm)
– As a result the top few nanometers should have
different d-spacing
17
21. Example 3: Residual Stress on thin films, layers
Unstressed sample Stressed sample
2θ
Intensity
21
22. Stress depth gradient
Very small angle of
incidence
analyzing stress
near surface
Larger angle of incidence
analyzing stress
near surface AND
deeper
Coating
Substrate
Coating
Substrate
22
24. Conclusions
• GIXRD is a powerful technique which can be
used to get information regarding:
– Phases present at the surface and as a function of
depth
– Strain/Stress at the surface and as a function of
depth
– Crystallographic changes at the sample surface
– Enhance layer diffraction signal
– Avoid overlapping peaks coming from different
depths on the sample
24
Notes de l'éditeur
The GIXRD indicates the existence of two austenitic phases at the surface of the sample. One phase is mainly seen at the surface while the other can be seen in the bulk material.