Analysis of Spectral Reflectance of Layers Formed by Anodic Etching of Silicon

Porous silicon structures are used to suppress spectral reflectance in many applications in optoelectronics and photovoltaics.
By anodizing p-type silicon substrates, we were able to create porous silicon structures. In the forming method, different etching conditions were applied, including electrical potential, current, and etching duration. Forming conditions influence sample structures. Inhomogeneous structures with different microstructure and optical properties are formed. The optical properties are studied in our approach by implementing the effective media approximation theory in the theoretical model of sample spectral reflectance. From an optimised spectral reflectance model, the thickness of generated layers, dielectric functions, and volume fractions of structural components were retrieved. The microstructure development during sample formation corresponds to the results of optical analysis.