Visible photoluminescence from silicon-ion-implantedSiO2sfilm and its multiple mechanisms

Abstract

Strong photoluminescence from silicon-ion-implanted thermal ${\mathrm{SiO}}_2$ film was investigated under various conditions. The photoluminescence spectrum of as-implanted samples or samples annealed in ${\mathrm{N}}_2$ at a temperature below 1000 °C consists of three bands centered at about 470, 550, and 630 nm. Annealing at a temperature above 1000 °C for a long enough time brings about one photoluminescence band peaking at about 730 nm. The peak wavelengths of these four bands are all independent of annealing or excitation conditions. As the annealing temperature is increased, 470-, 550-, and 630-nm bands are initially intensified and then weakened with the intensity maxima at 600, 300, and 200 °C, respectively; as the annealing time increases from 1 min, they are monotonously weakened. The 730-nm band is always strengthened whether with increasing annealing time or temperature within our experimental range. In addition, these four bands show different excitation behaviors. The discussion section argues that the 470-, 550-, and 630-nm bands result from different point defects in the bulk of silicon implanted ${\mathrm{SiO}}_2$ , while the 730-nm one results from luminescence centers at the interface between the nanocrystal silicon and ${\mathrm{SiO}}_2$ matrix.