A method for fabricating tensile-strained SiGe films via the oxidation of porous Si substrates with thin SiGe overlayers was reported. A 100nm thick Si0.77Ge0.23 film on a porous Si substrate was fabricated through self-limiting anodization of a heavily doped p-type Si substrate with an epitaxially grown intrinsic Si0.77Ge0.23 overlayer. The pseudomorphic Si0.77Ge0.23 film originally under 0.94% compressive strain on the porous Si substrate became completely relaxed by low-temperature (500C) oxidation of the porous Si substrate. Continued oxidation introduces an additional 0.71% tensile strain in the Si0.77Ge0.23 layer without the introduction of dislocations or cracks.

A Method for Fabricating Dislocation-Free Tensile-Strained SiGe Films via the Oxidation of Porous Si Substrates. J.Kim, B.Li, Y.H.Xie: Applied Physics Letters, 2007, 91[25], 252108