High current field emission from graphitic carbon nanosheets

A novel nanostructured carbon material termed carbon nanosheet, which is to be utilized in a high current (milliamp-level) field emission cathode, is presented. Carbon nanosheet (CNS) consists of vertically aligned graphitic sheets, with each sheet consisting of only a few graphite planes. The width of the individual sheets, a few nanometers thick, provides a large enhancement factor for low threshold-field emission. In contrast, the CNS prove to be quite rigid, being able to withstand photolithographic processing, making CNS a cathode material compatible with current micro-electronic device fabrication techniques. Utilizing an approach curve method, electron emission threshold fields of less than 5/Vμm are routinely achieved, as are current densities ∼1 mA/mm² with no sample degradation, and with total emission currents greater than 2 mA. Carbon nanosheets are currently being applied in novel back-gated field emission devices.