DIFFUSION OF COPPER IN POROUS SILICON

We present a study on the nature of diffusion of copper in p-type porous silicon. The diffusion of evaporated copper in porous silicon and deposition of metal ions in aqueous solution through the porous network was measured by monitoring the metal concentration depth profile as a function of time using Auger electron spectroscopy. We observed that increasing metal penetration from copper evaporated samples correlates with quenching of photoluminescence, in agreement with previous ion quenching results. We extracted a diffusion coefficient from Auger concentration depth profiles which was seven orders of magnitude lower than that expected for diffusion of copper in bulk crystalline Si at room temperature. Deposition of ionic species cannot be characterized as a simple diffusion process. The observed deposition rates were strongly dependent on the solution concentration. © 1995 American Institute of Physics.