Visible luminescences from thermally grown silicon dioxide thin films

Abstract

We introduce visible photoluminescences (PL) of violet (432 nm) and yellow (561 nm) at room temperature from thermally treated silicon dioxide thin films. These luminescences were very strong with a near infinite degradation time. At an oxide layer thickness less than 200 nm, these luminescences were not seen, even with high temperature annealing at about 1000 °C. As a result of photoluminescence, x-ray photoelectron spectroscopy, Fourier transform infrared, and high-resolution transmission electron microscopy measurements, we conclude that the violet PL originates from the nanocrystalline silicon formed in the silicon oxide film by the thermal strain effect between the silicon substrate and the silicon dioxide film, while the yellow PL originates from the radiative decay of self-trapped excitons that are confined to oxygen sufficient structures.