Si nanoparticles in SiO 2 An atomic scale observation for optimization of optical devices

International audiencePACS 61.46.-w-Structure of nanoscale materials PACS 68.37.-d-Microscopy of surfaces, interfaces, and thin films PACS 81.15.Cd-Deposition by sputtering Abstract-Three-dimensional imaging of silicon nanoclusters array in silicon-rich silicon oxide layers was evidenced and studied. The atom probe tomography technique allows to give the composition of the nanoclusters and the composition of the interface with the silica matrix. These results give new insights for the understanding of the properties of Si-based photonic devices. Introduction.-The development and optimization of Si-based photonic or memory devices [1-5], compatible with silicon integration technology, need to understand the precipitation of Si and the characteristic of Si nanoclusters (Si-nc) and the local chemical composition in Si/SiO 2 system. These Si-nc are deeply studied as sensitizer of erbium ions for silicon-based planar optical amplifier applications at 1.54 µm which is the wavelength used as standard in optical telecommunication [6-9]. A way to synthesize these nanoparticles consists in annealing at high temperature silicon-enriched silicon oxide (SRSO) leading to phase separation between Si and SiO 2. The understanding, modelling and prediction of the optical properties of these materials require an accurate determination of the nanostructure of the system such as the phase composition, the nanoclusters size distribution and number density as well as roughness, thickness and composition of the Si/SiO 2 interface. The Si-nc/SiO 2 interface has been suspected to governs, to a large extent, the optical properties of Si-nc. The presence of a thin ∼1 nm substoichiometric silicon oxide interface has been reported as playing a critical role in the emission properties [10,11]. In addition, it has been demonstrated that very small Si-nc, even amorphous, still have an efficient sensitiz-ing effect towards Er ions [9,12] and the relating energy transfer is highly dependent on the Si-nc-Er separating distance [13,14]. For these reasons, numerous studies focu