ACOUSTIC INVESTIGATION OF POROUS SILICON LAYERS

Porous silicon (PS) layers are formed on p(+)-type silicon wafers by e lectrochemical anodization in hydrofluoric acid solutions. Microechogr aphy and acoustic signature, V(z), have been performed at 1.5 GHz and 600 MHz, respectively, in order to study the elastic properties of PS layers. The thicknesses of PS layers were measured and longitudinal, s hear and Rayleigh velocities and Young's modulus were obtained as a fu nction of porosity. Equations showing the porosity dependence of bulk wave velocities and Young's modulus have also been proposed.