Phase transformation in SiOx/SiO2 multilayers for optoelectronics and microelectronics applications

Abstract

Due to the quantum confinement, silicon nanoclusters (Si-ncs) embedded in a dielectric matrix are of prime interest for new optoelectronics and microelectronics applications. In this context, SiO(x)/SiO₂ multilayers have been prepared by magnetron sputtering and subsequently annealed to induce phase separation and Si clusters growth. The aim of this paper is to study phase separation processes and formation of nanoclusters in SiO(x)/SiO₂ multilayers by atom probe tomography. Influences of the silicon supersaturation, annealing temperature and SiO(x) and SiO₂ layer thicknesses on the final microstructure have been investigated. It is shown that supersaturation directly determines phase separation regime between nucleation/classical growth and spinodal decomposition. Annealing temperature controls size of the particles and interface with the surrounding matrix. Layer thicknesses directly control Si-nc shapes from spherical to spinodal-like structures.

Evolution of shape, size, and areal density of a single plane of Si nanocrystals embedded in SiO2 matrix studied by atom probe tomography

“…Due to the well-known APT artifact, the local magnication effect, 30 some SiO 2 was articially introduced into the Si NCs, which blurred the Si NC/SiO 2 matrix interface. 31 Therefore, it is difficult to quantitatively evaluate the shape, size, and areal density of Si NCs by using Si iso-concentration surfaces, as the nal result is very sensitive to the chosen Si concentration threshold values. In order to quantitatively study these structural characteristics of Si NCs, a cluster identication algorithm has been employed.…”

“…Silicon nanocrystals (Si NCs) embedded in a SiO 2 matrix exhibit remarkable optical and electronic properties, and have been extensively studied due to their potential application in various elds such as photovoltaic, 1,2 optoelectronics, 3,4 and nanoelectronics. [5][6][7] The properties of these nanostructures are strongly dependent on Si NCs structural characteristics (shape, 8 size, [9][10][11][12] and areal density 13 ). Therefore, it is important to precisely control and analyze these structural characteristics of Si NCs.…”

“…[27][28][29] With APT, not only the 3D structural characteristics but the inside concentration of Si NCs can be studied. [30][31][32] Moreover the high sensitivity of the APT allows studying the presence and positioning of the impurities that can modify the electronic and optical properties of the Si NCs. Recently, APT has been employed to investigate dopant incorporation in Si NCs embedded in a SiO 2 matrix where Si NCs multilayer samples were used.…”

Raman scattering from confined acoustic phonons of silicon nanocrystals in silicon oxide matrix

“…The formation of Si-nc in an a-SiO 2 matrix by hightemperature annealing of SRSO films has been investigated by different authors [22][23][24]. It is common knowledge that SRSO is not stable at high temperatures and annealing leads to its decomposition into two stable components: Si and SiO 2 .…”

Electron tomography analysis of 3D interfacial nanostructures appearing in annealed Si rich SiC films

“…9 From atom probe tomography (APT) of SRSO films, a very thin compositionally distinct interfacial layer was observed between the Si NPs and the surrounding matrix. 10 In principle, electron tomography could be used to understand such interfacial layers, since one has access to composition and structure by this method and can also address larger sample volumes than in APT. Whereas electron tomography has shown Si nanostructures in the SRSO films, 11,12 a direct three dimensional (3D) visualization of the interfacial structure between the precipitated NPs and their surrounding matrix is still lacking.…”