Field emission of uniform carbon cone arrays grown on porous silicon substrate

Uniform carbon cones arrays with average height of 1μm were grown on porous silicon substrate using the hot filament chemical vapor deposition (HFCVD). Raman spectroscopy was used to characterize as-prepared carbon cones, which are composed of D peak (∼1352cm^-1), G peak (-1601cm^-1) and a broad peak at ∼1475cm^-1 attributed to hydrogenated carbon (a-C:H). It was found that both the immersion of porous silicon substrate in Fe₂(SO₄)₃ aqueous solution and the applied voltage in the deposition are vital to the growth of the carbon cones. Furthermore, the field emission properties of the as-prepared carbon cone arrays were studied, which shows an excellent field emission property. The threshold field is 2.2 V/μm, emission current of more than 80 μA could be obtained as applied electric field is 3.4 V/μm. The internal-tip mechanism has been proposed for cone arrays in order to account for the observed field emission.