Effect of back contact on field emission from carbon films deposited by very high frequency chemical vapor deposition

The effect of material and surface morphology of the back contact on field emission has been studied in carbon films deposited by very high frequency chemical vapor deposition at low temperature. The emission current was meas ured as a function of applied field for carbon films deposited simultaneous ly on various substrates coated with metals having different work functions (Ti, Cu, Ni, and Pt). Different metals demonstrated different types of mic rostructure and surface morphology. Therefore, the effect of back contact m orphology was especially studied. The material of the back contact influenc ed the emission properties, but no direct correlation between emission and the work function of metal was observed. The field emission threshold was f ound to be affected by the roughness of the back contact: a Ti contact with 270 nm roughness showed emission threshold of E-th= 3 V/mum, while a conta ct made of the same material, but with roughness of similar to2.5 nm had E- th= 13 V/mum. (C) 2001 American Vacuum Society.