Er doped Si nanostructures

In the present paper, we will review our recent work on Er-doped Si nanoclusters. We demonstrate that amorphous as well as crystalline Si clusters are efficient sensitizers for the Er3+ luminescence at 1.54 μm. The samples have been obtained by implanting Er in a film containing pre-formed Si nanocrystals. After the implant, samples have been treated at 900 °C for 1 h, in order to activate Er3+. It is shown that this annealing temperature is not enough to re-crystallize all of the amorphized Si clusters. However, even if the Si nanoclusters are in the amorphous phase, they can still efficiently transfer the energy to nearby Er ions. We present a model based on an energy level scheme taking into account the coupling between each Si nanocluster and the neighboring Er ions. By fitting the data, we were able to determine a value of 3×10−15 cm3 s−1 for the Si nanocluster–Er coupling coefficient. Moreover, a strong cooperative up-conversion mechanism, active between two excited Er ions and characterized by a coefficient of 7×10−17 cm3 s−1, will be shown to be active in the system, demonstrating that more than one Er ion can be excited by the same nanocluster. In addition, we found that the overall light emission yield of the Er related luminescence can be enhanced by using higher concentrations of very small nanoaggregates. Finally, room temperature operating electroluminescent devices based on Er-doped Si nanoclusters will be demonstrated.