SiOx/Si radial superlattices and microtube optical ring resonators

Scanning and transmission electron microscopy reveals that SiOx/Si layers can roll up into microtubes and radial superlattices on a Si substrate. These hybrid objects are thermally stable up to 850 degrees C and emit light in the visible spectral range at room temperature. For tubes disengaged from the substrate surface, optically resonant emissions with mode spacings inversely proportional to the tube diameter are observed and agree excellently with those obtained from finite-difference time-domain simulations. The resonant modes recorded are strictly polarized along the tube axis.(c) 2007 American Institute of Physics.