Electron emission from conduction band of diamond with negative electron affinity

Experimental evidence explaining the extremely low-threshold electron emission from diamond reported in 1996 has been obtained [K. Okano et al., Nature (London) 381, 140 (1996)]. Direct observation using combined ultraviolet photoelectron spectroscopy/field-emission spectroscopy proved that the origin of field-induced electron emission from heavily nitrogen (N)-doped chemical-vapor deposited (CVD) diamond was at conduction-band minimum utilizing negative-electron affinity (NEA). The significance of the result is that not only does it prove the utilization of NEA as the dominant factor for the extremely low-threshold electron emission from heavily N-doped CVD diamond but also strongly implies that such low-threshold emission is possible from other types of diamond and even other materials having NEA surface. The low-threshold voltage, along with the stable intensity and remarkably narrow energy width, suggests that this type of electron emission can be applied to develop a next generation vacuum nanoelectronic devices with long lifetime and high-energy resolution.