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New epi mbe dual filament effusion cell reactor epi-20
NEW EPI MBE DUAL FILAMENT EFFUSION CELL REACTOR EPI-20
New Factory Sealed Condition
EPI MBE Products Dual Filament Effusion Cell For EPI MBE Reactors
Model: EPI-20-DF-DT-LT-Special
Two Independent Heater Filaments
Operating Temp: 800 C-1200 C
Cell Flange Size: 2.75" (70mm)
Source Flange Size: 2.75" (70mm)
Power: Tip: 15.2V, 13.0A/Max
1 x P/N: 150334, Wrench, Allen - 5/64"
1 x P/N: 150314, Wrench, Allen - 1/16"
1 x P/N: 202015, Crucible Retaining Wire
Includes: EPI User's Guide, P/N: 204065, Rev 1.1
Includes: EPI Mating Connectors And High Temperature Solder For Connecting Them To Cable, There Are Three Other Connectors In The Box, One Connector Consists Of 3 Connector Set, Please Refer To Picture
Many elements require a specific thermal profile to achieve the highest quality of films grown. Dual filament effusion cells have been in use for a number of years providing the ability to tailor the thermal profile of an effusion cell. These cells can be run in either hot or cold lip operation or with uniform heat by simply changing the amount of power to each filament. One of the issues with MBE grown material has been the presence of oval defects in the films. One cause of this has been the condensation and reevaporation of Ga clusters at the lip of the crucible. It has been shown that defects can be reduced by operating the tip of the cell at a higher temperature than the source material melt. This method of operation has been come to be known as hot-lip operation. In hot-lip operation, the tip filament draws over 90% of the power used to heat the source material. This maintains the required higher temperature at the tip of the cell. When operating in this mode, users have seen a reduction of about an order of magnitude in the amount of defects seen in the films. For further reduction of defects, a new type of crucible is needed. Evaporation of aluminum has presented its own set of problems to MBE growers. One of the more common issues is the fact that aluminum will wet PBN crucibles. This causes aluminum to creep up the side walls of the crucible. In some cases, the aluminum will creep into the cell causing catastrophic damage to the cell. This effect is temperature related and users have been able to lessen the risk of material escaping the crucible by operating the cell in cold-lip mode. In cold-lip operation, only the base filament is used resulting in a colder surface at the tip of the crucible. When the aluminum reaches the colder surface at the top it generally will not travel further up the wall protecting the effusion cell from damage. This provides a safer operation mode of the cell and helps to prolong the life of the campaign and the effusion cell.
