As an approach to improve the stability and reliability of molybdenum field emitters with rough surfaces and impurities at tip apex, electrical aging was studied on the basis of the important tip heating mechanism, Nottingham heating, in dc and pulse mode. The effects of electric field in dc mode were investigated using single tips to avoid the averaging effect commonly arising in arrays. The fluctuations of emission currents were remarkably reduced after the exposure to high electric field (similar to100 MV/cm). It was responsible for surface migration and impurity desorption at tip apex achieved under high electric field. Since the continuous exposure to high electric field can,bring undesirable effects such as tip failures, electrical aging in pulse mode was also investigated. As the peak voltage of pulse Was increased, the fluctuation of emission current was rapidly reduced. From the electrical aging experiments for a 0.7 in. field emission display (FED), it was proven that the poor uniformity of FED could be considerably improved by electrical aging. (C) 2003 American Vacuum Society.