POROUS SILICON MEMBRANES FOR GAS-SENSOR APPLICATIONS

A porous silicon membrane (PSM) for an electrochemical oxygen microsen sor has been achieved. Both p(+)- and n(+)-type materials have been st udied. On the p(+)-type silicon, the porosity is found to be homogeneo us through the complete thickness of the membrane, while n(+)-type mem branes appear less homogeneous. The permeability of the PSM to oxygen has been tested with the help of a classical sensor. The diffusion pro cess is found to be much more efficient for n(+)-type than for p(+)-ty pe membranes. For PSM thicknesses ranging from 150 to 270 mu m, the di ffusion time varies from 7 to 10 min.