The structural changes of porous silicon (PS) samples during oxidation are investigated and analyzed using various microscopy techniques and x-ray diffraction. It is found that the surface roughness of oxidized PS layers increases with the oxidation at 200-400°C and decreased at 600-800°C. At 800°C a partially fused surface is observed. The oxide formed on the wall of porous silicon skeleton is amorphous. The shifts of Si(400) peaks are observed in the x-ray diffraction patterns, which are correlated to the lattice deformation induced by thermal expansion coefficient mismatch between the grown SiO 2 and the residual Si, and to the intrinsic stress caused by the Si-O bonds at the Si-SiO 2 interface. These explanations are supported by thermomechanical modeling using three-dimensional finite element method.
ASJC Scopus subject areas
- Physics and Astronomy (miscellaneous)