Reflectance
is
the
fraction
of
incident
electromagnetic
power
that
is
reflected
at
an
interface.
Measurement
of
this
material
property provides a
handful
of
parameters
such
as
temperature,
growth
rate,
thickness,
composition,
etc.
The
equipment
(SVTA) combines
traditional
pyrometry
with
specular
reflectometry
to
provide
a
single
instrument
to
monitor
both
substrate
temperature
and
film
thickness
in
real
time.
It
is
a
technique easy
to
implement and
a
very
common
in-situ metrology
tool
used
in
molecular
beam
epitaxy
systems. It
is
of
uttermost
importance
when
dealing
with
semiconductors
or
heterostructures
which
are
not
properly
analysed
with
a
simple
pyrometer.
Hence
the
name
of
reflectance
corrected
pyrometry. Associated
with
reflection
high
energy
electron
diffraction
(RHEED),
ion
gauges
and
mass
spectrometry,
reflectance
can
also
provide the
growth
rate
of
the
layers
and
assist
in
inferring
the
flux
of
the
cells
and
the
thickness
of
the
grown
material.
Finally,
the
data
can also
be
analysed
to
characterize
the
layer's
composition.