Field emission characteristics of patterned free-standing diamond films

By depositing diamond films on Mo substrates (thickness=3 mm) with approximately 0.2 mm wide and 1.0 mm deep hole-type grooves, we easily obtained tubular-volcano-type patterned free-standing diamond films. The hole diameter at the film surface decreased with the film growth, eventually forming circular cones. Protrusions as high as ∼50 μm occurred at the substrate side of the films. For the tubular-volcano-type patterned free-standing diamond films, field emission characteristics were greatly enhanced, including lower turn-on voltages and higher current density. The surface morphologies of the films were correlated with the field emission characteristics. Reasons for the enhancement of the field emission characteristics for the tubular-volcano-type patterned free-standing diamond emitters were discussed.