ON THE ORIGIN OF BLUE-LIGHT EMISSION FROM GE-NANOCRYSTALS CONTAINING A-SIOX FILMS

We have studied the photoluminescence of a-SixGeyO1-x-y films with ave rage Ge-nanocrystal sizes ranging from over 100 nm down to 2 nm. No sy stematic peak shift of the luminescence bands at 3.0 eV and 2.0 eV wit h the diameter of the nanocrystals is observed. Comparision with a sim plified confinement model shows that quantum size effects cannot expla in the blue luminescence. We propose the Ge-0(2) defect as a likely so urce for this band, based on considerations about the crystallization process. (C) 1998 Academic Press Limited.