Enhanced field emission from aligned multistage carbon nanotube emitter arrays

In this work we report on the synthesis and field emission properties of carbon nanotube multistage emitter arrays grown on porous silicon by catalytic thermal chemical vapor deposition. The vertically oriented multistage array structures consisted of SWNTs and thin MWNTs grown on MWNTs, confirmed by TEM and Raman analysis. Higher field emission current similar to 32 times and low threshold field similar to 1.5 times were obtained for these structures in comparison to only MWNT arrays. The enhanced field emission results for these multistage emitters are a consequence of higher field concentration, which is similar to 3 times more than MWNTs.