Investigation of aging effects in porous silicon

Porous silicon has many properties useful for optics applications, which include an ability to produce thin films with a wide range of refractive indices and the ability to easily fabricate multilayer structures. However porous silicon does have some non-optimal properties due to the very nature of its porous structure, namely its large surface area. The porous silicon surface is quite reactive making properties of porous silicon thin films, such as refractive index, unstable in an ambient environment. The purpose of this work is to investigate the aging of porous silicon and the effects of aging on the optical and physical properties of the thin films. Reflectance and FTIR spectroscopy are used to investigate the porous silicon layers by observing shifts in optical thickness and changes in chemical structure of the thin films. The aging process was simulated by annealing samples at temperatures such that only reactions that occur at room temperature were promoted.