High field emission current density from structured CNT bundle cathodes

We report on the field emission (FE) properties of structured cathodes with CNT bundles of about 2 μm height and 2-3 μm width grown onto n-Si wafers with trimetallic Mo/Al/Ni layers by chemical vapour deposition (CVD). Bundle arrays with a pitch of 100 μm provide highly efficient and well-aligned FE at ~15 V/μm. The highest current density, however, was achieved for cathodes with a pitch of 5 μm. Local measurements with a anode of Ø 150 μm yielded stable currents up to 500 μA at 400 V. Integral pulsed measurements of the whole cathodes showed fairly homogeneous FE at 100 mA/cm² on the luminescent screen and maximum current densities up to 4.4 A/cm² with a Cu anode.