Abstract: The present invention provides a porous semiconductive structure, characterized in that the structure has an electrical conductivity of 5·10?8 S·cm?1 to 10 S·cm?1, and an activation energy of the electrical conductivity of 0.1 to 700 meV, and a solid fraction of 30 to 60% by volume, and a pore size of 1 nm to 500 nm, the solid fraction having at least partly crystalline doped constituents which are bonded to one another via sinter necks and have sizes of 5 nm to 500 nm and a spherical and/or ellipsoidal shape, which comprise the elements silicon, germanium or an alloy of these elements, and also a process for producing a porous semiconductive structure, characterized in that A. doped semimetal particles are obtained, and then B. a dispersion is obtained from the semimetal particles obtained after step A, and then C. a substrate is coated with the dispersion obtained after step B, and then D. the layer obtained after step C is treated by means of a solution of hydrogen fluoride in water, and then E.