Field emission properties of self-structured CNT networks deposited at temperatures below 150°C

Self-structured CNT networks were grown on n-Si substrates using a recently developed CVD process based on a reactor with high and low temperature zones. This CVD process separates the synthesis of CNTs at typically 800°C from their deposition at temperatures below 150°C on cheap substrates like glass and polymer foils. Depending on the various process parameters, self-structuring into well-separated hills of entangled CNT bundles occurs which also show some outgrowth of vertically-oriented single-wall CNTs. These cathodes provide random but well-distributed field emission with around 10000 emitters/cm² at an electric onset field (for 1 nA) of ~2.5 V/μm. Local measurements of Ø 150 μm spots reproducibly yield stable currents of at least 200 μA and maximum currents up to 1 mA. Integral pulsed measurements of the whole cathodes reveal fairly homogeneous emission resulting in at least 10 mA/cm² only limited by the heat load on the phosphor screen.