Suppression of leakage current via formation of a sidewall protector in the microgated carbon nanotube emitter

In this work, we have fabricated a triode field emitter using directly grown carbon nanotubes (CNTs) as an electron emission source. Vertically aligned CNTs have been grown in the centre of the gate hole, to the size of 1.5µm in diameter, using thermal chemical vapour deposition. A comparison of the field emission characteristics of two types of microgated nanotube emitter with and without a sidewall protector for the gate hole is made. A sidewall protector formed by the method of tilting the substrate can enhance the electrical characteristics by suppressing the problem of short circuits between the gate and the CNTs. The leakage current of an emitter with a sidewall protector is approximately sevenfold lower than that of an emitter without a sidewall protector at a gate voltage of 100 V.