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The EpiCentre 282 manipulator is a full heating
and rotation stage intended primarily as a retrofit instrument for
existing molecular beam epitaxy (MBE) systems. This component differs from the
EpiCentre 100 and 346 by supporting the substrate at right angles to the
general centre line axis. Two axis’s of rotation combine to provide
continuous azimuthal rotation for the sample and a partial primary
rotation for stage positioning.
An awareness of existing right-angled manipulator design drove us to
completely rethink the concept of this stage. By stacking two of our
existing rotary feedthroughs, we are able to achieve a dual axis,
concentric rotation system, which eliminates the head positioning gear
train used by all other manufacturers.
By incorporating our existing heater module technology into this
component, we are able to improve on both ultimate temperature
capability and uniformity. |
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| System design
philosophy |
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Stage positioning |
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The azimuthal drive is achieved
through a bevel gear train, actuated by the MD16
MagiDrive. Particular
attention has been paid to the design of this section of the instrument,
as it is conventionally the source of premature failure.
The gear train is supported in a
precision housing that ensures the gear pitch distance does not reduce
for increased temperature. The substrate cradle drive mechanism uses the
inverse geometry of competitive manipulators, which enables us to fit
large ballraces in an arrangement, tolerant of the thermal
stresses. This all results in low radial run out of the cradle
during rotation, which is important for serious RHEED measurements. |
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The EpiCentre 282 may be fitted with a
simple manual positioning selector. Alternatively, a fully automated
system is available. Manual positioning is
achieved by thimble adjustment of an MD35H
MagiDrive. A positioning ring with an external spring loaded pin, is
attached to the drive. Releasing the pin enables the drive to be rotated
to a number of pre-selected positions. These ensure simple and
repeatable locking of the stage for sample transfer, growth, flux
monitoring and RHEED. The RHEED position may be finely tuned to allow
for chamber geometry variations.
The automated option provides stepper motor control
over the MD35H. Bakeable switches protect the system from travel beyond
its limits and provide an absolute homing point. When coupled to the PSMCC
series, this system allows precise positioning to be achieved
throughout the desired range. |
| Heater Modules |
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The 282 series is available with all
the 100 series heater elements including PgG (pyrolitic graphite coated
graphite) and PBNG (pyrolitic boron nitride coated graphite) click
here to view this data. These heater elements offer the best ratio
of heat radiating surface to gap and therefore run at lower temperatures
for a given power transmission. The heater module is also available with
a quartz guard to protect the element during sample transfer.
Please click
here to see the ‘Heater Element Power Graph’. This graph
plots the required Volts or Amps (left scale) to reach temperatures
ranging from 400ºC-820ºC. The graph then illustrates the total power
(Watts) required for the same temperature range (right scale). |
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Substrate spin,
positioning, temperature control and power supply options
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The 282 may be fitted with DC of
stepping motors for the continuous substrate rotation. Both
options may be controlled using the DC
motor controller or programmable stepper motor controller PSMCC
series.
The heating element is designed to match existing
power supplies, however, should a new or improved system be required, we
recommend the TC1 temperature controller and 1.2kW Glassman supply. |
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Click
here for the EpiCentre 282 drawing and specification table |
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Please contact
sales to receive your full
quotation
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