Heavy B atomic-layer doping is performed by B atomic-layer formation on Si(100) using B2H6 and subsequent Si capping layer deposition using SiH4. By B2H6 exposure on Si(100) at 180 degrees C, the B atom amount tends to saturate self-limitedly at around 1.4 x 10(15) cm(-2) (two atomic layers (AL)). In the case of exposure at 500 degrees C, the B atom amount increases with time and exceeds two AL. Additionally, B oxide formation by air exposure is observed for 500 degrees C but not for 180 degrees C. Therefore, it is suggested that the H adsorption on the B AL is kept at 180 degrees C and H desorption from the B AL proceeds at 500 degrees C. It is also found that the SiH4 exposure on the B AL at low temperatures such as 180-300 degrees C effectively improves the electrical activity of B and suppresses lattice strain generation even with the subsequent Si capping at 500 degrees C. These results demonstrate that the low temperature reaction of SiH4 as well as B2H6 open the way to extremely heavy B atomic-layer doping. (C) 2009 Elsevier Ltd. All rights reserved.