Electron field emission from an array of micro-patterned monolithic diamond tips with varyingsp2content has been systematically investigated. The experimental results show that the field emission characteristics can be improved and the turn-on electric field can be reduced more than 50&percent; by increasingsp2content. Two hypotheses are proposed as an explanation of the effect ofsp2content on the field emission characteristics of diamond tips: the lowering of the work function due to defect-induced band generated bysp2content in the diamond lattice and an increase in the field enhancement factor due to embeddedsp2–diamond–sp2cascaded microstructures. ©1997 American Institute of Physics.