Germanium hut nanostressors on freestanding thin silicon membranes

The heteroepitaxial growth of Ge on thin Si membranes can lead to significant bending under self-assembled Ge hut nanostructures. Undercut silicon-on-insulator mesas approximate a Si freestanding membrane and serve as a crystalline substrate for the growth of Ge huts. Synchrotron x-ray microdiffraction shows a local curvature on the lateral scale of the size of the hut and an overall bending of the freestanding region. In comparison with conventional mechanically rigid substrates, the freestanding film can bend significantly. We have found a local radius of curvature of 6 mu m beneath huts on 30-nm-thick Si membranes. (C) 2005 American Institute of Physics.