Preserving long-term emission stability of carbon nanotube field emitter using aluminum layer

Carbon nanotube (CNT) field emitter was fabricated, and then its emission stability was evaluated with three different anode structures; indium tin oxide (ITO)/glass, ZnS:Cu,Al(green phosphor)/ITO/glass, and Al/ZnS:Cu,Al/ITO/glass. It was found that the electron emission from CNTs to the phosphor layer degrades much faster than the emission to ITO layer does. The current decay time from 100 μA/cm² to 50 μA/cm² for ITO/glass and ZnS:Cu,Al/ITO/glass were 250 h and 20 h, respectively. Such rapid decay in emission current with the phosphor-coated anode was found to be attributed to the formation of Zn particles on CNTs during the field emission. However, the deposition of aluminum layer on the phosphor, in other words, using the anode structure of Al/ZnS:Cu,Al/ITO/glass recovered the stability that is comparable to that with an ITO/glass. The aluminum layer was found to efficiently prevent phosphor elements from being degassed, preserving the long-term emission stability of carbon nanotubes.