Active emitters based on nanostructured Si
The present paper deals with the use of Si nanoclusters as efficient sensitisers for Er and Nd rare earth ions or as active emitters in Si/SiO2 Fabry-Perot microcavities. The films have been fabricated using the reactive magnetron sputtering of a silica target. The energy transfer efficiency from Si-nc towards Er ions has been studied as a function of the fabrication parameters (hydrogen rate, annealing temperature) through time resolved PL intensity measurements on Er-doped silicon-rich silica layers. A multilayer approach has been developed to determine the critical parameters such as the optimum Si-nc size and the characteristic interaction distance Si-nc-Er ions which govern the transfer Si-nc-Er. Thus we have found an optimum size of 4 nm for the Si nanocluster and a maximum spacing of 0.4 nm between the Si-nc sensitisers and the Er3+ ions. First results on the efficient sensitising effect of Si nanocluster towards Nd3+ ions are also reported. Concerning the optical planar Si/SiO2 microcavities, spectral, spatial and temporal photoluminescence behaviour of the Si/SiO2 multilayers confined inside the resonator are studied. The comparison with a reference sample evidences the effect of the distributed Bragg reflectors structure on the intensity enhancement and the directional characteristic of the emission.
Keywords: reactive magnetron sputtering, rare earth, silicon nanocrystals, Fabry-Perot microcavities, active emitters, silicon nanoclusters, nanotechnology