(invited) Growing Si Nanocrystals within a-Si Nanoclusters Embedded in a-SiO2: Evolution of Photoluminescence

L.J. BORRERO-GONZÁLEZ; L.A.O. NUNES; F.E.G. GUIMARÃES; J. WOJCIK; P.MASCHER; A. M. GENNARO; M. TIRADO; D. COMEDI

Seattle

Encuentro; 221st ECS Meeting May 6 - May 10, 2012 Seattle, Washington; 2012

The Society of Solid State and Electrochemical Science and Technology

We combine X-ray absorption, electron spin resonance and Raman spectroscopies, X-ray diffraction and photoluminescence (PL) techniques to determine the structure and luminescence mechanisms in Si nanoclusters (Si-ncls) embedded within Si oxides at various intermediate formation stages. The Si-ncls/oxide systems are fabricated by thermally annealing plasma-enhanced chemical vapor deposited Si-rich Si-oxide films. The structural and chemical orders in the amorphous oxide matrix, the Si-ncls amorphous and crystalline volume fractions and sizes, the dangling bond density and PL spectra and decay rates are followed closely as a function of the annealing temperature. The results can be interpreted by a crystalline core/amorphous shell model for the Sincls. The important role of the shell, often ignored in the literature, is discussed. As the Si-ncls crystalline cores grow at the expense of thinning amorphous shells, the PL undergoes a transition from a regime dominated by disorder-induced effects to a situation where quantum confinement prevails.