A method to fabricate strained Si films is reported via the oxidation of a thin Si film on a porous Si substrate. The Si film can be put under tensile stress in a controllable fashion through the expansion of the porous Si upon low temperature oxidation. The thin Si layer on porous Si substrate can be fabricated using a self-limiting anodization of epitaxially grown intrinsic Si on a heavily doped p-type Si substrate. Tensile strain of up to similar to 1% is observed in 100 nm thick Si films, making it suitable for the various device applications based on strained Si. (c) 2006 American Institute of Physics.