Rare-earth (Er,Nd)-doped Si nanostructures for integrated photonics
Résumé
The present article deals with the use of Si nanoclusters as efficient sensitizers towards Er3+ or Nd3+ ions. To take advantage from such an nc-mediated excitation, a maximum coupled rare-earth (RE) ions is sought through a careful engineering of the composition of the active material. For this purpose, confocal reactive magnetron co-sputtering process has been used for the fabrication of the co-doped layers. Depending on the deposition parameters and/or on annealing treatment, the photoluminescence (PL) properties of the RE ions have been analyzed and optimized. By an accurate monitoring of the deposition parameters and thermal treatment, the number of Er ions coupled to silicon nanocrystals has been multiplied by a factor of 4, with respect to the data reported so far for ‘‘standard'' samples. Concerning neodymium, we have shown, on the other hand, that a concentration quenching occurs when the Nd concentration within the silicon-rich silicon oxide (SRSO) layer exceeds a threshold value, leading to a dramatic decrease of the Nd PL. Two decay times have been deduced from the time-resolved PL experiments and have been linked to the surrounding of the Nd3+ ions.