Fig. 2: Design of a harvest mode µTEG.

a Illustration (not to scale) of the side-view cross section through one n-p thermocouple with contact metallization and heat exchanger layers to a surface aluminum thermal contact pad. b Optical microscope plan view image of the Al coated thermal contact pad, with electrical contacts to the n and p sides of the thermopile array. (Middle contact pad is to the substrate and is not used.) c Plan view design (to scale) looking down on one thermopile unit cell forming the harvest mode µTEG used to generate the data of Fig. 3. Each dark-colored solid square represents a group of four blade elements. The dark red lines are silicide electrical contacts to the n⁺ and the p⁺ wells. As depicted, the thermal contact would be above the page and the substrate behind the page, so heat Q flows perpendicularly into the plane of the page as indicated while electric current flows from n⁺ well to p⁺ well through the metal contacts bridging the n- and p-sides shown in part (a).