The value of the Young's modulus of silicon is often required for engineering designs using micro-electro-mechanical systems (MEMS) technology. However, silicon is an anisotropic crystalline material and so the answer to the question, "What is the Young's modulus of silicon?" is, "it depends, and it can vary by up to 45%". Fortunately, it is straightforward to determine the correct answer for any situation. A condensed answer to the question and explanation is given here.
http://silicon.mhopeng.ml1.net/Silicon/
This pdf file below shows how to calculate the Young's modulus and Poisson ratio based on the Stiffness matrix
http://www.kaajakari.net/~ville/research/tutorials/elasticity_tutorial.pdf
