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10-4 Torr the isolation valves are opened and the entire system is allowed to pump down using
the mechanical pumps for approximately 12 hours. Then the ion pumps and the cryo-pumps are
turned on and the mechanical pumps are shut down. The system is pumped down using the ion
pumps to the least achievable atmospheric pressure usually 10-10 to 10-12 Torr. The system is left
to pump down for about 48 hours to create the UHV conditions.
After the required pressure is achieved, the load-lock chamber is isolated from the rest of
the chamber and using the isolation valve present between the load-lock chamber and the
preparation chamber, shown in Figure 18. It is then bought to atmospheric pressure. The moly28H
blocks are then mounted manually on the carousel holder, shown in Figure 19.
29H
Figure 18. Load-lock chamber of the III/V MBE system.
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