Method for measuring work function

A method for measuring work function, the method comprising the steps of:

• (a) providing an initially untreated field emission electron source having a carbon nanotube tip and a spaced anode, the carbon nanotube tip being used as a cathode emitter, the carbon nanotube tip and the spaced anode having a predetermined spaced distance therebetween;
• (b) applying a voltage between the cathode emitter and the anode and measuring a first current-voltage curve of the untreated field emission electron source in a vacuum environment and at the predetermined spaced distance;
• (c) forming a layer of a field emission material whose work function is to be measured, the layer of the field emission material being formed at least on the surface of the carbon nanotube tip to thereby result in a treated field emission electron source;
• (d) measuring a second current-voltage curve of the treated field emission electron source in the vacuum environment and at the predetermined spaced distance;
• (e) achieving two Fowler-Nordheim curves calculated from the two current-voltage curves according to the Fowler-Nordheim equation;
• and
• (f) comparing the two Fowler-Nordheim curves and further calculating the work function of the field emission material to be measured.