Estimation of physical constants of silicon-based polymer thin films using surface acoustic waves and their application to liquid sensor

Physical constants of poly(di-methyl silane) are estimated from the characteristics of the surface acoustic wave (SAW) propagating along poly(di-methyl silane)/(128/spl deg/rot.Y-X) LiNbO/sub 3/ structure. The values of c/sub 11/ and c/sub 44/ are estimated to be (5.9/spl plusmn/0.9)/spl times/10/sup 10/ and (1.2/spl plusmn/0.3)/spl times/10/sup 10/ N/m/sup 2/, respectively. Using the obtained stiffness constants and density of poly(di-methyl silane), the leaky SAW propagation character is estimated from the numerical calculation based on the first-principle-equations. As a result, it is found that liquid/polysilane/(128/spl deg/rot.Y-X) LiNbO/sub 3/ structure is useful for estimating physical constants of the liquid loaded on the device surface, i.e., the surface of the polysilane thin film.