Simulation of Porous Silicon Formation by Diffusion Limited Reaction David Barth EPS 109 Final Project

Porous Silicon Formed by electrochemical reaction Can be considered two diffusion limited half reactions 𝑆𝑖+2 𝐻 2 𝑂+2 ℎ + →𝑆𝑖 𝑂 2 + 𝐻 2 +2 𝐻 + 𝑆𝑖 𝑂 2 +6𝐻𝐹→𝑆𝑖 𝐹 6 2− + 𝐻 2 𝑂+2 𝐻 + Tried to simulate both by separate random walk simulations Replaced second random walk with probability of dissolution at each step

Porous Silicon

Growth and Cross Sectional View Visualization of thousands of points in 3D is tricky. Patch data is too slow. Porosity is much lower than we actually see in porous silicon. ~ 5% Crystal Structure and electrical properties are very important, and not captured here. To start simulation, run psiEtching.m