Carbon Nanosheet Cathodes for Use in Milliamp Class Field Emission Devices

Summary form only given. Field emission sources have distinct advantages such as short turn-on time, high power efficiency, low thermal signature, modulation control and the ability to be a variable current source that are desirable for high-current applications. However, scale-up of current density, device lifetime and device robustness has been limited to date. In this talk we present recent results using carbon nanosheets (CNS) as the field emission source in a high-current, back-gated device. Carbon nanosheets consist of free-standing graphene layers 100 microamps, 3% at max current; 100 sec/cycle) 200 hours, again without failure. Furthermore, the sweep-to-sweep repeatability was remarkably high over the entire 200 hours and the standard deviation of the maximum current was 10 mA/mm 2 and internal modulation to GHz frequencies. Testing of prototype devices has produced upto 3.5 mA of current and lifetimes of over 20 hours. The primary device failure mode is dielectric breakdown due to Au diffusion. New Pt-based devices are under construction; testing results from these devices will also be presented