Theoretical study of thermal instability of Mo tips with and without diamond coatings

Thermal effects in molybdenum tips with and without diamond coatings are an alyzed. An attempt is made to identify:; 'intrinsic'' mechanisms that might trigger catastrophic vacuum breakdown. A new theoretical treatment is empl oyed to study the thermal response of tip emitters which takes into account the correlative effect between field emission and its resultant temperatur e rise at the tip. In both uncoated and chemically vapor deposited diamond coated Mo tip emission regimes, the location of the hot spot is found to be at the tip apex. It is also shown that higher emission current densities c an be obtained from a coated tip before the melting temperature of Mo is re ached compared to that of an uncoated tip for the same geometry and dimensi on. (C) 1999 American Vacuum Society. [S0734-211X(99)08002-6].