Ion
Gauges
(IG)
are
hot
cathode
gauges. They
comprise
a
filament
that
acts
as
an
electron
source,
a
grid
that
accelerates
the
electrons
and
a
collector
to
detect
ionized
gases
formed
by
collisions
between
the
electrons
and
atoms inside
the
grid.
Tungsten
(W)
can
be
operated
up
to
100
Watts
being a
good
ion
gauge
filament.
However,
In
and
Ga
modify
the
work
function
of
the
W
filaments,
and
so
either
Yttrium
(Y)
or
Thorium
(Th)
coated
Iridium
(Ir)
filaments
are
more
better
choices
for
III-V
systems.
This
is
especially
true
for ion
beam
flux
monitors
(BFMs,
aka
monitoring
ion
gauges
(MIGs)). The
Ir-filament
can
be
operated
with
a
controller,
which
improves
stability.
The
QNC-MBE
tool
is
equipped
with
IGs
in
all
its
chambers
and
a
BFM
for
flux
monitoring.
