Decrease of electron paramagnetic defect density and enhancement of electron field emission in annealed carbon films

We have studied the effect of the paramagnetic defects in carbon films on t he field-emission properties. The paramagnetic defects in carbon films orig inating from the carbon dangling bonds were measured using electron spin re sonance (ESR). We found a reduction of the dangling bond density in the ann ealed carbon films in N-2/H-2 atmosphere from ESR spectroscopy. The anneale d films with lower defect densities, i.e., dangling bonds, showed an improv ed characteristic of higher emission current density as well as a lower tur n-on electric field in the Fowler-Nordheim type tunneling. Also in the anne aled carbon films a correlation is observed between the decrease of band ga p estimated from the electrical conductivity and the reduction of dangling bond density. The earlier results indicate that the enhancement of the emis sion current level in the annealed carbon films is related to the decrease of the ESR centers. (C) 2000 American Institute of Physics. [S0021-8979(00) 05310-X].