Multiple-layered effective medium approximation approach to modeling environmental effects on alumina passivated highly porous silicon nanostructured thin films measured by in-situ Mueller matrix ellipsometry

摘要

Graphical abstract Display Omitted Highlights • Optical changes in alumina passivated highly porous silicon from SCTFs during controlled exposure to toluene vapor are reported. • Inspection of individual Mueller matrix elements show sensitivity to adsorption. • Adsorption of toluene into void region between nanostructures cannot be described with a single inhomogeneous layer. • Multiple-layer effective medium approximation approach is necessary. Abstract Optical changes in alumina passivated highly porous silicon slanted columnar thin films during controlled exposure to toluene vapor are reported. Electron-beam evaporation glancing angle deposition and subsequent atomic layer deposition are utilized to deposit alumina passivated nanostructured porous silicon thin films. In-situ Mueller matrix generalized spectroscopic ellipsometry in an environmental cell is then used to determine changes in optical properties of the nanostructured thin films by inspection of individual Mueller matrix elements, each of which exhibit sensitivity to adsorption. The use of a multiple-layered effective medium approximation model allows for accurate description of the inhomogeneous nature of toluene adsorption onto alumina passivated highly porous silicon slanted columnar thin films.