Direct formation of strained Si on insulator has been investigated by using laser annealing. The silicon on insulator (Sol) and amorphous Si layers deposited on Sol substrates were irradiated with ail excimer laser. After the laser annealing, crystal Si layers with a strain of similar to 0.6% were successfully formed on the buried oxide. Spectroscopic ellipsometry and atomic force microscopy measurements revealed the high crystallinity (similar to 100%) and small surface roughness (similar to 0.64 nm) of the formed layers. These results demonstrate that laser annealing technique will be a useful tool to fabricate strained Si on insulator without SiGe buffer layers. (c) 2005 Elsevier B.V. All rights reserved.