High
resolution
x-ray
diffration (HRXRD)
is
an
ex-situ
characterization
method
and
it
is
the
core
tool
to
analyze
nano-scale
epitaxial
structures.
X-rays are
produced
from
a
source
where
electrons
are
ejected
from
a
cathode,
collide
on
a
metal
plate
(in
our
case copper)
and
excite
inner-shell
electrons in
the
metal, resulting
in
the
emission
of
strong
spectral
lines.
The
output
is
conditioned
as
a
Cu
K
α
quasi-parallel
beam,
strikes
on
the
crystalline
sample
at
different
incidence
angles
and
the
scattering
signal
is
collected
by
a
detector.
The
working
principle
behind
HRXRD
is
Bragg’s
law,
which
states
that when
the
x-ray
incident
onto
a
crystal
surface
with
angle
of
incidence, θ,
it
will
reflect
back
with
a
same
angle
of
scattering, θ.
When
the
path
difference, d is
equal
to
a
whole
number, n, of
wavelength,
a
constructive
interference
will
occur.
The
path
difference
is
the
separation
between
the
crystal
planes
that
caused
the
reflection.
The
Jordan
Valey
QC3
HRXRD
system
can
be
operated
in
different
scanning
modes:
omega
scan
(rocking
curve),
detector
scan,
coupled
scan
and
reciprocal
space
map.
The data
can
be
analyzed
by
a
powerful
software
built
with
dynamic
x-ray
scattering
models,
where
useful
parameters
such
as
layer
thicknesses,
composition,
tilt
and
strain
can
be
obtained
upon
curve
fitting.
