STABILITY OF CARBON FIELD-EMISSION CURRENT

The stability of field emission (FE) current is evaluated for glassy carbon FE tips. Experimental findings are as follows: (1) Instability is proportional to the product of FE current level and the pressure under operation. (2) Instability is large for CO ambient and small for H2 ambient. (3) Instability consists mainly of steps and spikes instead of 1 f{hook} type. (4) Instability is reduced by heating the lip during operation. As a result, it is concluded that instability is due to dislodgement of adsorbed molecules on the tip surface by impinging ions formed near the tip by FE electron beam bombardment. © 1979.