In a simple-structured single-temperature furnace, a three-step rising temperature process has been used to fabricate carbon nanotube (CNT) arrays and carbon nanotube bundles by pyrolysis of ferrocene/melamine mixtures on silica and ceramic wafers, respectively. The structure and composition of the CNTs are investigated by scanning electron microscopy, transmission electron microscopy, x-ray photoelectron spectroscopy and electron energy-loss spectroscopy (EELS). EELS spectrum shows that CNTs grown on the two different kinds of substrates are pure carbon tubes. CNTs on smoothing silica wafer are highly orientated and have uniform outer diameters of about 22 nm and varying lengths from 10 to 40 μm. CNTs grow in top growth mode and exhibit the stacked-cup-like structures. CNT bundles on rough ceramics wafer are randomly orientated. They have varying outer diameters of 15—80nm and lengths up to one hundred of micrometers. They exhibit two types of shapes, bell-like and dome-like. The effect of substrate morphologies on the morphology and structure of CNTs has been discussed.