Electroluminescence from C- and Si- rich silicon oxides in continuous wave and pulsed excitation
Résumé
This work reports the electroluminescence from carbon-and silicon-rich silicon oxide layers under continuous wave and pulsed excitation. The films were fabricated by Si and C ion implantation at low energy in 40 nm thick SiO2, followed by annealing at 1100degC. In continuous wave excitation, white electroluminescence has been observed. Structural and optical studies allow assigning it to Si nanocrystals for the red part of the spectrum, and to C-related centers for the blue and green components. The external efficiency has been estimated to 10-4%. Electrical characteristics show a Fowler-Nordheim behavior for voltages above 25 V, equal to the onset of electroluminescence. This suggests that light emission is related to the impact ionization of radiative centers. In pulsed excitation, electroluminescence has been observed for a voltage of less than 10 V. It is shown that the C-rich centers are not involved in this process, but a solution to obtain their excitation is proposed.