Field emission degradation of carbon nano-tubes

Carbon nanotubes (CNTs) are known for their excellent field emission characteristics and are considered as prima candidates as cold-cathode electron emitters. On the other hand, for these materials to be used in practical devices, such as pseudo spark switches, they need to be capable of operating for many hours without loosing the ability of field emission characteristics. In this work, we present the results of field emission data of the random multi-walled-CNTs (MWCNTs) and their degradation over 100 runs as a function of time. Here the MWCNTs are considered with and without impurity clusters in CNTs. The CNT samples used in these studies are grown in-house by thermal chemical vapor deposition (CVD) method under different growth conditions. Field emission measurements of CNTs are carried out at the room temperature in vacuum (pressure of 10"6 Torr). From the field emission data, turn-on voltage, saturation current density, and Fowler-Nordheim plots of each sample are determined. These experiments are repeated for several times. In some cases over 100 runs of field emission measurements for the same sample are carried out. Turn-on voltage and saturation current density data as a function of time (i.e. function of number of measurements) per sample is presented. Based on these data, each sample\´s field emission degradation over time is estimated and presented.