Size dependence of the luminescence properties in Si nanocrystals

We have observed strong room temperature photoluminescence (PL) from high t emperature annealed. substoichiometric silicon oxide (SiOx) thin films. pre pared by plasma enhanced chemical vapor deposition. The PL peaks have been found in the 650-950 nm spectral range, peak intensities increase with the annealing temperature up to 1250 degrees C. A marked redshift of the lumine scence peaks has been observed by increasing the Si concentration of the Si Ox films as well as the annealing temperature. Transmission electron micros copy analyses have demonstrated that Si nanocrystals (nc), having mean radi us ranging between 0.7 and 2.1 nm, are present in the annealed samples, and that their size increases with increasing the Si content and the annealing temperature. Structural and optical data have been related and discussed i n terms of quantum carrier confinement. (C) 2000 Elsevier Science S.A. All rights reserved.