High-Current Electron Sources

Mainstream commercial electron sources are based on thermionic emission in which electrons are “boiled” off the surface of metals or semiconductors when the thermal energy of the electrons is sufficient to overcome the potential barrier holding the electrons within the material. Even though thermionic cathode technology is quite successful, thermionic-based cathodes require high-vacuum and high-temperature to operate, which results in inefficient power consumption, poor reliability, and portability constraints. The demand for more efficient electron sources has driven the research of cold cathode technologies, particularly field emission. Field emission arrays (FEAs) are potential cold cathodes that could be used in a variety of vacuum micro- and nano-electronic device applications such as field emission displays (FEDs), high frequency amplifiers, gas ionizers, X-ray sources, and multi-electron beam lithography. In the majority of these applications current level, stability, reliability, lifetime, and emission uniformity are the key metrics for cathode performance.