Optical and structural properties of SiO 2 co-doped with Si-nc and Er³⁺ions

Abstract

We present a study on erbium-doped silicon rich silicon oxide (SRSO:Er) thin films grown by the magnetron cosputtering of a three confocal cathodes according to the deposition temperature and the annealing treatment. It is shown that several parameters such as the stoichiometry SiO x , the Erbium content and the fraction of agglomerated Silicon are strongly influenced by the deposition temperature. Especially, an increase of the fraction of agglomerated-Si concomitant to a reduction of the erbium content is observed when the deposition temperature is raised. These structural differences have some repercussions on the optical properties that lead to better performances for high-temperature deposited material. It is illustrated by the Er-PL efficiency that is higher for 500°C-deposited than for RT-deposited sample at all annealing temperatures. Finally an investigation of the different emitting centres within the films is performed with a cathodoluminescence technique to highlight the emission of optically-active defect centers in the matrix. It is shown that some oxygen vacancies, namely Silicon-Oxygen Deficient Centers, have a strong contribution around 450-500 nm and are suspected to contribute to the energy transfer towards Er 3+ ions.

Nature and Role of Various Si-Based Sensitizers for Er³⁺ Ions in Silicon-Rich Silicon Oxide Thin Films

“…We can see that, for the 150 nm-thick sample, the Si-nc contribution is increased at the expense of the SiODC one when the voltage is increased. This indicates some reabsorption or energy transfer from SiODC to Si-nc, as shown elsewhere [6,7]. Therefore, one can argue that SiODC are sensitizers for Si-nc and thus feed the Si-nc with further energy to be transferred to Er 3+ .…”

“…This may be explained by the creation of new non radiative defects that quench the SiODCs luminescence and/or the absorption of the emission by Si-nc. All these emitting centers are potential sensitizers for Er 3+ ions and further investigations are available in previous studies [6,7] While well-defined emissions of SiODC and Si-nc are detectable from the sample 150 nm-thick, only SiODC contribution is clearly seen in the 50 nm-thick sample. For the latter, a weak shoulder in the low energy range can be attributed to combined contributions of Si-nc and NBOHC.…”

Photon cutting for excitation of Er3+ions in SiO2sensitized by Si quantum dots

“…Further details of the sample preparation procedure and material characterization can be found elsewhere. 24,25 Following preliminary selection, samples with the most intense 1.54-μm Er-related emission have been chosen for the investigation of optical properties.…”