Suppression of Auger deexcitation and temperature quenching of the Er-related 1.54 μm emission with an ultrathin oxide interlayer in an Er/SiO2/Si structure

Abstract

A strong enhancement of the Er3+-related 1.54 μm emission was obtained from Er-doped porous silicon (PSi), when host PSi was slightly oxidized before Er incorporation. Separate measurements of the energy transfer and the Auger deexcitation between carriers in Si crystallites of preoxidized PSi and Er3+ ions were measured as functions of the preoxidized time or the thickness of the SiO2 interlayer, and revealed that a 1 nm order thick SiO2 interlayer between Si crystallites and Er3+ ions suppressed the Auger energy backflow strongly with only a moderate decrease of the carrier mediated Er3+ excitation. A thin SiO2 interlayer was also effective at suppressing the phonon-assisted energy backtransfer at high temperatures, leading to a strong room temperature Er3+-related 1.54 μm emission.

Optical activation of Si nanowires using Er-doped, sol-gel derived silica

“…Yet Er 3+ luminescence from bulk, crystalline Si is known to undergo severe temperature quenching [3]. Thus, we conclude that the Er 3+ ions excited via carriers generated in Si-NWs are actually in the sol-gel derived Er-doped silica film that is coating the Si-NWs, in agreement with previous reports that Er 3+ ions in a nm-thin silica shell around Si have both high carrier-mediated excitation efficiency and high Er 3+ luminescence efficiency irrespective of quantum effects [12]. …”

Tuning the Er3+ sensitization by Si nanoparticles in nanostructured as-grown Al2O3 films

“…In this case the minimum separation of an Er 3+ ion to the upper surface of a Si NP underneath will be of ϳ1 nm. For Er 3+ in silica-based systems characteristic energy transfer distances from 0.5 to 2-3 nm have been reported, [1][2][3] and therefore for the film with s = 4 nm it is suggested that there is negligible energy transfer from the Si NPs to the Er 3+ layers deposited before the Si NPs, which are at a separation of 4 nm, and that the effective energy transfer is mainly due to the Er 3+ layer deposited after each Si NP layer. From these results it can thus be estimated that there is effective energy transfer from Si NPs to Er 3+ ions in Al 2 O 3 for a distance of ϳ1 nm.…”

“…As a result the NPs remain amorphous and the film is not modified by diffusion processes that might modify the original structure, as in most previous reports. [1][2][3]5 This procedure opens a route to the development of one step low-temperature processing for codoped nanostructured waveguide devices.…”

“…It has been demonstrated that in silicabased systems the Si NPs ͑usually nanocrystals͒ act as efficient sensitizers for Er 3+ . The interaction between the Si NPs and the Er 3+ ions occurs on the nanometer scale and therefore is sensitive to the dopant distribution, [1][2][3][4] and can be affected by the presence of atomic defects. 5 Usually, in silica-based systems, Si has to diffuse upon thermal treatment in order that the NPs precipitate from the initial mixed amorphous Si-SiO 2 structure and thus there is little control over the Si NP distribution.…”

“…5 Usually, in silica-based systems, Si has to diffuse upon thermal treatment in order that the NPs precipitate from the initial mixed amorphous Si-SiO 2 structure and thus there is little control over the Si NP distribution. [1][2][3]5 It is therefore desirable to develop preparation techniques that allow the formation of the Si NPs in situ during film growth. In addition, further understanding of the energy transfer from the Si NPs to the Er 3+ ions may be achieved by studying the efficiency of such energy transfer in nonsilica-based materials.…”