Design of a Thermoelectric Layer for a Micro Power Generator

In this article, an n-type polycrystalline silicon (poly-Si) layer for a micro thermoelectric generator (TEG) was designed using Taguchi methods. Design parameters for this experiment were thicknesses of oxide and poly-Si,films, and fabrication conditions in the boron ion-implantation process. Based on an L-9 (3(4)) orthogonal array, nine different poly-Si testpieces were fabricated on 525 mu m-thick Si substrates. Oxide and poly-Si films were deposited using the low pressure chemical vapor deposition (LPCVD) method on cleaned wafers. Subsequently, phosphorous ions were implanted in the poly-Si layers with different process conditions. The crystalline structures of the fabricated specimens were observed using X-ray diffraction (XRD). The XRD analysis results demonstrated that each specimen was well crystallized with (2 2 0) orientation. The Seebeck coefficient and electrical conductivity including the Hall coefficient, Hall mobility, and carrier concentration were measured. The power factor of each testpiece was calculated. Through analysis, the power factor of an optimized poly-Si layer was predicted to be 798 mu Wm(-1) K-2. The optimized design parameters were 0.2 mu m-thick oxide films, 1.5 mu m-thick poly-Si films, 130 keV energy of the ion implantation process, and 10(15) cm(-2) dopant dose of the phosphorous ions.