Efficient electron emitter utilizing boron-doped diamond tips with sp2 content

A practical technique to enhance the electron emission of diamond tips by incorporation of boron dopant and sp2 content is reported. The effects of boron doping on electron field emission from an array of micro-patterned polycrystalline pyramidal diamond microtips with varying sp2 content have been systematically studied. The field emission characteristics of undoped and boron-doped diamond tips are significantly improved by increasing sp2 content of diamond tips. By increasing sp2 content, the turn-on electric field can be reduced more than 50% for both undoped and boron-doped diamond tips. Likewise, the turn-on electric field of the diamond tips with higher sp2 content decreases substantially with boron doping. A new field emission mechanism, that is, an increase in the field enhancement factor due to hole accumulation via the formation of cascaded sp2-diamond-sp2 embedded microstructures in diamond tips, is a possible explanation for the enhanced effects of boron doping and sp2 content on the diamond field emission characteristics. q1999 Elsevier Science B.V. All rights reserved.