Vibrational and electronic properties of stabilized wurtzite-like silicon

Microcrystallites of hexagonal silicon (Si) have been deposited during the elaboration of SiO 2 films. A good quality crystallographic structure is clearly identified in this uncommon material through microdiffraction, Raman scattering and photoluminescence techniques. Raman spectra exhibit two lines, one in crossed polarizations and the other in parallel polarizations. The temperature effect on phonon frequencies is discussed. The optical gap, estimated until now only through calculations, is found to be 1.45 eV at a temperature of -140°C. We propose that a grain silicon oxide coating plays a crucial role in the stabilization of this metastable phase of Si.