Field emission from aligned carbon nanotubes grown on patterned oxide layers

A study on field emission from carbon nanotubes is reported. The CNTs are selectively grown on patterned silicon dioxide on silicon substrates using chemical vapour deposition. To understand the influence of the oxide layer thickness on the associated field emission characteristics, the oxide layer thickness is varied from 15 nm to 100 nm. Field emission measurements are carried out in a parallel plate configuration, with an anode-cathode spacing of 100 μm, an anode of 1 mm diameter and a vacuum of the order of 10^-7 Torr. Results show that carbon nanotubes grown on patterned silicon dioxide layer exhibit reasonable electron emission characteristics. The emission threshold field varies from 1.9 V/μm to 3.25 V/μm as the oxide thickness is increased. The emission behaviour seems to have a linear relation with the oxide thickness in the measured range of the samples. The influence of the oxide layer thickness is further discussed on the basis of Raman measurement.