101 questions to ask when buying a new MBE system

Faebian Bastiman

Ordering (or even expressing an interest in) a new MBE system bears a tremendous responsibility. In a radical way you are in fact influencing the future development of MBE technology. Great care and consideration is needed in order to specify the system you want, rather than the system that is currently available. Here are a few points to consider:

  1. What do you want to grow?
  2. Which manufacturer will you choose?
    1. What is the overall system cost?
    2. What are the features?
    3. How much of the system can be customized to your needs? If not all why not!?
    4. What is the manufacturer’s customer service like?
    5. How much will the maintenance items cost?
  3. How big is the system? i.e. What is the system foot print?
  4. How much does the system weight?
  5. What system layout will you use?
    1. Where will the racks go?
    2. Where will the desk go?
    3. How long do the interconnecting cables and pipes need to be?
  6. Where should the system be installed?
    1. Will a lab be sufficient? (Loaded question, answer: Yes)
    2. Do you really need a cleanroom? (Loaded question, answer: No)
    3. Will you allow the MBE operator to experience natural light!!!
    4. Can you position the system to make guided tours easily?
    5. Will you open your facility to the public annually?
    6. What are the advantages of a “showcase” system?
      1. For you and your facility?
      2. For funding applications?
      3. For gaining PhD students?
      4. For supporting local industry?
      5. For the local community
      6. For the manufacturer?
    7. What clothing do you need to wear whilst operating the system?
    8. How will the cleanliness of the room be maintained?
  7. What other costs (initial outlay) are associated with the system install?
    1. How much is the water cooling loop?
    2. Will the water cooling be triple backed up against failure?
    3. Do you know what “triple backed up” is?
    4. How much is the LN2 loop?
    5. How much is the LN2 daily usage?
    6. How much is the pressurized gas loop?
    7. Will you use dry, compressed air as much as possible? And if not why not!?
    8. How much is the 3 phase electric?
    9. What is the current consumption?
    10. How much is the UPS?
    11. How much is a back up generator?
  8. What pumps do you need?
    1. What type of turbo do you want? Oil bearings or magnetic bearing?
    2. Are you getting dry scroll pumps? And if not why not!?
    3. Are you getting a cyropump for the growth/preparation/FEL chambers?
    4. What type of compressor are you installing? Air or water cooled?
    5. Are you getting an ion pump for the growth/preparation/FEL chamber?
    6. What type ion pump controller are you getting? A 1/2/4 pump controller?
    7. Do you need a phosphorus trap?
    8. Will you neutralize the phosphorus with water?
    9. Where will you send the waste phosphorus / phosphoric acid?
  9. What is the most economical means of running the system (day to day)?
    1. Where will you buy your samples?
    2. Will you buy 2/3/4”?
    3. Will you ¼ your samples?
    4. Will you repolish your samples?
    5. Where will you buy your Cu gaskets?
    6. Will you support local industry by buying your Cu gaskets from a local manufacturer?
    7. Where will you recycle your Cu gaskets?
    8. Where will you buy your crucibles?
    9. How will you regenerate your crucibles?
    10. Will you be using inserts for Al and Bi?
    11. Where will you buy your cell material?
    12. Will you use 6N5 or 7N material?
    13. How can you recycle energy (heat and cold)?
    14. Can you gain publicity and press by installing a “green” facility?
  10. What is the warranty of the system?
  11. What service plan does the manufacturer offer for maintainence and repair?
    1. How will you regenerate the LN2 cooling panel every 5 years?
    2. How will you regenerate the cell dividers and shutters?
    3. How will you regenerate the sample holders (platens)?
    4. How expensive are the sample holders (platens)?
    5. How will you maintain the cells?
  12. What ancillary hardware do you need?
    1. Whose PSU will you take?
    2. Whose PID controller will you take?
    3. Whose Ion Gauge controller?
    4. What makes a “good” Ion Gauge Contoller?
    5. What digital inputs and outputs do you need?
    6. What analogue inputs and outputs do you need?
  13. What software will you buy?
    1. Does the software enable automatic sample transfer?
    2. Does the software enable batch processing of multiple recipes?
    3. Does the software automatically pump down and vent the load lock (FEL)?
    4. Does the software automatically protect against water failure?
    5. Does the software allow in situ ellipsometry/reflectivity control?
    6. Does the software automatically tune to the pyrometer and/or thermocouple temperature?
    7. Will the software monitor the vacuum and valves?
    8. Will the software data log the ion gauges and PID loops?
    9. Is the software customizable/adaptable/expandable?
    10. What do you actually want from the software?
    11. What do you actually need from the software?
    12. How will you contribute to MBE development by adapting your specification and enabling the evolution of this technology?
  14. Is the sample transfer automatic? And if not why not!?
  15. Which RHEED system will you buy?
    1. Will it have bakeable cables? And if not why not!?
    2. Will it have software control?
    3. Will it have µ-Metal shielding?
    4. Does the system require µ-Metal shielding along the beam path?
    5. Can the manufacturer supply µ-Metal shielding?
    6. Is the RHEED well aligned?
    7. Will you require a port aligner or magnets to enable 360° access?
    8. Will the RHEED image capture be automatic?
    9. Can you record videos of the RHEED during growth?
    10. Can you control the azimuth/rotation from the software? What is the resolution?
  16. Is the monitoring ion gauge (MIG) integrated into the manipulator?
  17. How is the MIG head replaced?
  18. How easy is it to perform maintenance?
    1. Do you need to recover your phosphorus and double bake the system?
    2. How much of the infrastructure needs removing before bakeout?
    3. Is the bakeout a box-and-fan or a jacket system?
  19. How are the samples loaded?
    1. What is the position and orientation of the load lock (FEL)?
    2. Is it degassed to 125°C? And if not why not!?
    3. How many samples can be loaded concurrently?
    4. Is there sample storage available in the preparation chamber or elsewhere?
    5. How many sample holders (platens) do you need?
    6. What sizes and shape of cut out will you need in you sample holders (platens)?
    7. How are the samples actually physically mounted?
    8. How long does it take to exchange a sample on a sample plate (platen)?
  20. How are samples outgassed?
    1. What is the maximum temperature of the outgas stage?
    2. Can you oxide remove there?
    3. Can you have Ga/H cleaning?
    4. Can you have Auger/RHEED on the outgas?
  21. What is the orientation of the growth chamber?
    1. Is the manipulator vertically or horizontally aligned?
    2. How many cells do you need? 10? 12? 118?
    3. How many projects do you need to run simultaneously?
    4. Will there be problems with Ga spillage?
    5. How will liquid Ga spillage be trapped and removed from the system?
    6. Can you take this opportunity to improve the existing MBE technology?
  22. Who will run the system?
  23. How many samples do you want per day?
  24. What is the temperature gradient across the substrate?
  25. What is the temperature difference on different sample holders (platens)?
  26. How can you ensure the results will be systematic?
  27. How can you develop the software and hardware to eliminate systematic errors?
  28. What are the “bottle necks” to MBE throughput?
  29. What are the current limitations of MBE design?
  30. What have I missed?
  31. Where can I go to gain more information?
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