Characteristics of Hafnium Nitride Field Emitter Array at Low Temperatures

Electron emission characteristics of field emitter arrays with hafnium nitride cathode were investigated at the low temperature of 140 K. The characteristics at 140 K showed little difference from those at room temperature immediately after cooling down. After a long term operation, the collector current showed a gradual dicrease. The reason for the decrease would be due to the adsorption of the residual gas molecules onto the emitter surface, which raised the work function of the emitter surface. Detailed analysis with an aid of Seppen-Katamuki analysis revealed that the decrease of the collector current during the long term operation was attibuted to the decrease in the number of the active tips: contribution of the emission from the emitters with higher work function became negligible to those with lower work function.