I guess the question also relates to what materials you want to grow. Our small-sample (10mm) MBE systems sit in non-cleanroom labs. We have a laminar flow cabinet next to the load chamber for final surface prep which we hope will help yields on processed material. But we are not trying to grow optical quality semiconductors in these. Our 3" wafer system and another 10mm MBE are in a proper cleanroom and we can make high quality semiconductor materials with these.