A method of fabricating a thermoelectric converter, comprising: forming a plurality of first thermoelectrically active elements (133a; 237; 330a) of a first thermoelectric semiconductor material having a first Seebeck coefficient and a plurality of second thermoelectrically active elements (133b; 249; 330b) of a second thermoelectric semiconductor material having a second Seebeck coefficient in a layer (115; 215) of silicon-based material, the layer of the silicon-based material having a first surface, a second surface opposite to the first surface, and a first thickness between the first surface and the second surface, the first and second thermoelectrically active elements each being formed to extend through the first thickness, from the first surface to the second surface; and forming electrically conductive interconnections (143, 413; 257, 413) over at least one of the first surface or the second surface of the layer of the silicon-based material (115; 215), the electrically conductive interconnections each electrically interconnecting a first thermoelectrically active element of the plurality of first thermoelectrically active elements and a corresponding one of the plurality of second thermoelectrically active elements; and forming an input electrical terminal and an output electrical terminal electrically coupled to the electrically conductive interconnections, wherein the first thermoelectric semiconductor material includes porous silicon and the second thermoelectric semiconductor material includes a silicon-based material selected from a group consisting of porous silicon and polycrystalline silicon. forming a plurality of first thermoelectrically active elements (133a; 237; 330a) of a first thermoelectric semiconductor material having a first Seebeck coefficient and a plurality of second thermoelectrically active elements (133b; 249; 330b) of a second thermoelectric semiconductor material having a second Seebeck coefficient in a layer (115; 215) of silicon-based material, the layer of the silicon-based material having a first surface, a second surface opposite to the first surface, and a first thickness between the first surface and the second surface, the first and second thermoelectrically active elements each being formed to extend through the first thickness, from the first surface to the second surface; and forming electrically conductive interconnections (143, 413; 257, 413) over at least one of the first surface or the second surface of the layer of the silicon-based material (115; 215), the electrically conductive interconnections each electrically interconnecting a first thermoelectrically active element of the plurality of first thermoelectrically active elements and a corresponding one of the plurality of second thermoelectrically active elements; and forming an input electrical terminal and an output electrical terminal electrically coupled to the electrically conductive interconnections, wherein the first thermoelectric semiconductor material includes porous silicon and the second thermoelectric semiconductor material includes a silicon-based material selected from a group consisting of porous silicon and polycrystalline silicon.