Luminescence and Si and Ge nanocluster formation in silica

Cathodoluminescence (CL), high resolution transmission (HR-TEM) and scanning transmission electron microscopy (STEM), and energy dispersive X-ray analysis (EDX) have been used to investigate Si and Ge cluster formation in amorphous silicon dioxide layers and their respective luminescence behavior. In Ge+ ion implanted SiO2 an additional violet (V) Ge related emission band is identified at (410 nm). A postimplantation thermal annealing at temperatures Ta=700, 900, 1100 ∘C for 60 minutes in dry nitrogen or vacuum leads to a hugh increase of the violet luminescence up to 900 ∘C, followed by a decrease towards 1100 ∘C. The strong increase of the violet luminescence is associated with formation of low-dimension Ge aggregates like dimers, trimers and higher formation; the following decay of luminescence is due to further growing to Ge nanoclusters.