Ultrathin porous nanoscale membranes, methods of making, and uses thereof

A method of producing a porous nanoscale membrane comprising:

• providing a substrate having a multilayered film formed on one side of the substrate and a mask formed on an opposite side of the substrate, the multilayered film comprising a nanoscale film between sacrificial films wherein the nanoscale film comprises an amorphous semiconductor material;
• etching the substrate, beginning from the masked opposite side of the substrate and continuing until a passage is formed through the substrate, thereby exposing the film on both sides thereof to form a membrane;
• annealing the amorphous semiconductor material, before or after said etching, under conditions effective to convert the amorphous semiconductor material into a crystalline semiconductor material having a plurality of spaced pores in the nanoscale film;
• and
• removing the sacrificial films to produce a porous nanoscale membrane exposed on both sides thereof.