Comparison of stress, strain, and elastic properties for porous silicon layers supported by substrate and corresponding membranes

• Characterization of mechanical properties of porous silicon with different porosities were studied using high resolution XRD.
• Our results indicated that mechanical properties reduce with increasing porosity.
• Mechanical properties of two different porous layers, either supported by or detached from the substrate were examined.
• Constraint in interatomic spacing is origin of lattice constant expansion in planes perpendicular to surface.

This paper describes characterization of mechanical properties of porous silicon (PS) layers with different porosities using high resolution XRD. The XRD measurement determined various mechanical properties of PS such as; Young modulus, Poisson's ratio, and lattice parameter expansion. Our results indicated that mechanical properties reduce with increasing porosity. Also, the mechanical properties of two different porous layers, either supported by or detached from the substrate were examined. Comparison of the two porous layers showed that the constraint in the interatomic spacing is the origin of the lattice constant expansion in the planes perpendicular to the surface. This phenomenon can be useful for gas sensor applications.