The single-walled carbon nanotubes (SWNTs) have been considered as an alternative material for nanoelectronics, such as field-effect transistor or nanosensor, due to their unique electronic properties. However, an in situ growth process that can synthesize SWNTs with good position, diameter, and directional control is not yet available. Recent developments on the synthesis of SWNTs by deposition of ultrathin catalyst metal on the support of high specific areas were quite encouraging. In this study, high-yield vertically aligned SWNT arrays are demonstrated by in situ growth process with/without dielectric support material. In the case with dielectric support material, the role of dielectric support layer and the mechanisms of SWNT growth control will be discussed. Then, in the case without dielectric support material, the iron-based catalytic system revealed the ability to grow SWNTs from single-crystal silicon wafer directly, giving rise to the possible application of device structure with specific process module, for example, vertically aligned carbon nanotube field-effect transistor device may need to grow SWNT from doped-silicon area (source or drain well). In these experiments, micro-Raman spectroscopy and high-resolution transmission electron microscopy were utilized to characterize the SWNT properties and structures. (c) 2006 American Vacuum Society.