No abstract

The quest to improve silicon properties for optoelectronic applications is a challenge for many researchers. The answer appears to rely on microelectronic compatible materials enhanced with embedded nanostructures. We used reactive sputtering to produce films with non-stoichiometric silicon nitride. The excess of silicon in those samples is then aggregated by subsequent thermal annealing. By carefully choosing deposition parameters and annealing temperatures, an improved photoluminescence response was obtained. The temperature effect on the photoluminescence from the samples was investigated between 10 and 300 K. We observed a moderate signal improvement at lower temperatures, with no significant spectral response change. The composition of the samples was obtained by Rutherford Backscattering Spectrometry and the sample thickness was measured by spectral ellipsometry. We observed a large increase in photoluminescence response for samples with increased oxygen concentrations.

In the present work, we confectioned light emitting SiOx (x<2) samples using reactive sputtering. By controlling the oxygen concentration in the deposition chamber (range from 0.5% up to 10), an excess of silicon was created in the formed silicon oxide films. Only after a thermal annealing (temperatures from 1050ºC to 1100ºC), the samples showed the photoluminescence (PL) effect. Silicon nanocrystals formed during the thermal annealing were the responsible for the observed PL signal when excited with the 488nm line of argon laser. We also performed thermal annealing at 450ºC, using forming gas ambient to passivate the silicon nanocrystals interface. The result was a significant improvement in PL signal. Furthermore, the Rutherford Backscattering Spectrometry experiment showed that the deposition time is an important parameter to create the silicon excess and achieve light emission.