Strain-induced lateral self-organization in Si/SiO2 nanostructures

Abstract

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“…5b provides an indication of the presence of relatively big (5-6 nm long/3.6 nm high) and laterally elongated Si crystallites. This experimental finding is in perfect agreement with those reported in the literature for similar multilayer structures; elongated Si nanocrystals are observed to form within the a-Si layers with lateral dimension of the Si nanocrystals that far exceed their perpendicular size (Grom et al 2000;Tsybeskov et al 2010;Zacharias et al 1999). According to Tsybeskov et al, the crystallization in nanometerthick Si layer is inhibited close to the a-Si/SiO 2 interface due to the high strain determined by the different thermal expansion coefficients of Si and SiO 2 (Tsybeskov et al 2010).…”

“…This experimental finding is in perfect agreement with those reported in the literature for similar multilayer structures; elongated Si nanocrystals are observed to form within the a-Si layers with lateral dimension of the Si nanocrystals that far exceed their perpendicular size (Grom et al 2000;Tsybeskov et al 2010;Zacharias et al 1999). According to Tsybeskov et al, the crystallization in nanometerthick Si layer is inhibited close to the a-Si/SiO 2 interface due to the high strain determined by the different thermal expansion coefficients of Si and SiO 2 (Tsybeskov et al 2010). As a consequence, homogeneous nucleation of Si nanocrystals occurs in the center of the a-Si layer, away from the interfaces with the SiO 2 , and the growth of the Si nanocrystals is highly favored in the direction parallel to the Si/SiO 2 interface (Tsybeskov et al 2010;Zacharias et al 1999).…”

“…According to Tsybeskov et al, the crystallization in nanometerthick Si layer is inhibited close to the a-Si/SiO 2 interface due to the high strain determined by the different thermal expansion coefficients of Si and SiO 2 (Tsybeskov et al 2010). As a consequence, homogeneous nucleation of Si nanocrystals occurs in the center of the a-Si layer, away from the interfaces with the SiO 2 , and the growth of the Si nanocrystals is highly favored in the direction parallel to the Si/SiO 2 interface (Tsybeskov et al 2010;Zacharias et al 1999). These laterally extended Si nanocrystals are more stable than the small ones that tend to dissolve or to merge together forming relatively larger structures.…”

“…It was clearly demonstrated that the crystallization temperature increases rapidly with decreasing a-Si layer thickness below 10 nm . Moreover, the nucleation of Si nanocrystallites near the SiO 2 interface is strongly inhibited in the 1-nm-thick a-Si region close to the SiO 2 film (Tsybeskov et al 2010;Zacharias and Streitenberger 2000). These phenomena have been correlated to confinement of the a-Si layers in onedimension by the surrounding SiO 2 matrix and to strain arising from the mismatch between the Si and SiO 2 thermal expansion coefficients.…”

“…Several works analyzed the thermodynamic and kinetic of Si thermal crystallization in a-Si/SiO 2 superlattices (Grom et al 2000;Tsybeskov et al 2010Tsybeskov et al , 1999Zacharias and Streitenberger 2000;Zacharias et al 1999). It was clearly demonstrated that the crystallization temperature increases rapidly with decreasing a-Si layer thickness below 10 nm .…”