The presently disclosed invention provides for the fabrication of porous anodic
alumina (PAA) films on a wide variety of substrates. The substrate comprises a
wafer layer and may further include an adhesion layer deposited on the
wafer layer. An anodic
alumina template is formed on the substrate. When a rigid substrate such as Si is used, the resulting anodic
alumina film is more tractable, easily grown on extensive areas in a uniform manner, and manipulated without danger of
cracking. The substrate can be manipulated to obtain free-standing alumina templates of high
optical quality and substantially flat surfaces PAA films can also be grown this way on patterned and non-planar surfaces. Furthermore, under certain conditions the resulting PAA is missing the
barrier layer (partially or completely) and the bottom of the pores can be readily accessed electrically. The
resultant film can be used as a template for forming an array of nanowires wherein the nanowires are deposited electrochemically into the pores of the template. By patterning the electrically conducting adhesion layer, pores in different areas of the template can be addressed independently, and can be filled electrochemically by different materials. Single-stage and multi-stage
nanowire-based thermoelectric devices, consisting of both n-type and p-type nanowires, can be assembled on a
silicon substrate by this method.