Atomic-layer doping of N in Si epitaxial growth by alternately supplied NH3 and SiH4 was investigated using an ultra-clean low-pressure chemical vapor deposition (LPCVD). Atomic layer order nitrided Si(1 0 0) with N amount of 3 x 10(14) cm(-2) are formed by NH3 exposure at 500 Pa and 400 degreesC. By subsequent SiH4 exposure at 25 Pa and 500 degreesC, Si is epitaxially grown on the nitrided Si(1 0 0) with N amount of 3 x 10(14) cm(-2). High quality epitaxial growth of the multi-layer N-doped Si film composed of the N layers of 3 x 10(14) cm(-2) and the 3.0 nm Si spacer is achieved. On the other hand, in case of 0.5 nm Si spacer, the crystallinity of N-doped Si film is degraded by the increase of N atoms with Si3N4 structure after the second nitridation. (C) 2003 Elsevier B.V. All rights reserved.