PHOTOLUMINESCENCE OF SIO2 LAYERS IMPLANTED WITH SI+ IONS AND ANNEALEDIN A PULSED REGIME

SiO2 layers thermally grown on Si are implanted with Si+ ions at energ ies of 100 and 200 keV in a dose equal to similar to 10(17) cm(-2). Tw o types of pulsed anneals are employed: at 900-1200 degrees C for 1 s and at 1050-1350 degrees C for 20 ms. Photoluminescence is observed in the visible and near-infrared regions of the spectrum after implantat ion. In the initial annealing stages the photoluminescence intensity d rops, but after an anneal at 1200 degrees C for 1 s or at 1350 degrees C for 20 ms, it increases sharply by tens of times. According to the data from Raman spectroscopy and high-resolution electron microscopy, this corresponds to the formation of Si nanocrystals in SiO2. The anne al times employed rule out the diffusion-controlled growth of Si nanoc rystals, but they could form as a result of the solid-phase crystalliz ation of amorphous inclusions. The correlation between the sharp enhan cement of the luminescence and the formation of Si nanocrystals attest s to a quantum-size mechanism for its appearance. (C) 1997 American In stitute of Physics.