Cold field electron emitters or “cold cathode” electron sources based on field emission have been continuously researched for decades, with resurgence in recent years motivated by advances in carbon nanostructures. This research is motivated by the significant technological applications enabled by the desirable properties of field-extracted cold electrons in comparison to heat induced electron emissions. The use of carbon nanotube field emitters in display applications and its potential advantages have been known for some time. In addition though, attributes such as minimal beam spread and fast response would also allow for advances in other critical applications, including microwave electronics and x-ray sources. These attributes would lead to superior communication and radar, and new functionalities and modalities in imaging technology for medicine and security. These latter applications, however, require an emitter capable of high emission current, which so far has been in the realm of thermal sources.
Accordingly, a need exists for a cold field or “cold cathode” field emitter which could provide relatively high emission current densities without failure. Moreover, it would also be beneficial to provide methods of forming such emitters at ambient temperatures and which are amenable for large scale manufacturing processes.