Ultrasonic investigation of mesoporous silicon
Résumé
In this paper, an ultrasonic characterization of mesoporous silicon is proposed. The goal of this study is to estimate the porosity rate and the thickness of porous silicon layers. Two sets are formed in order to retrieved independently each parameter: one with similar porosity and another with similar thickness. Secondly, an immersed ultrasonic measurement technique and a modeling based on material homogeneization and Biot theory are presented.This modeling is used to simulate a wave propagation through the porous layer. An optimization between simulated and experimental spectra, based on a genetic algorithm, allows porosity and thickness to be estimated. These measured properties are compared to the results of a destructive evaluation. A good retrieval of porosity and thickness is observed, even if layer thickness is small compared to wavelength of the ultrasonic wave inside porous silicon.