Influence of Grain Size on the Thermoelectric Properties of Polycrystalline Silicon Nanowires

• DOI: 10.1007/s11664-014-3207-1
• Publication Date: 2014-05-11T17:32:29Z
• Authors: F. Suriano; M. Ferri; F. Moscatelli; F. Mancarella; L. Belsito; S. Solmi; A. Roncaglia; S. Frabboni; G.C. Gazzadi; D. Narducci
• Keywords: Thermal doping; High-temperature annealing; Doping elements; Nanowires; grain boundaries; Nanowire; polycrystalline silicon; thermal conductivity; Electrical and Electronic Engineering; Electronic, Optical and Magnetic Materials; Condensed Matter Physics; Materials Chemistry2506 Metals and Alloys; Thermoelectric equipment; Doping techniques; Thermoelectric figure of merit; Phosphorus; 02 engineering and technology; Inhibition effect; Grain growth; Thermal conductivity measurements; Thermoelectric properties; Thermal conductivity; Grain boundaries; Polysilicon; Doping (additives); 0210 nano-technology; Nanowire, polycrystalline silicon, grain boundaries, thermal conductivity

The thermoelectric properties of doped polycrystalline silicon nanowires have been investigated using doping techniques that impact grain growth in different ways during the doping process. In particular, As- and P-doped nanowires were fabricated using a process flow which enables the manufacturing of surface micromachined nanowires contacted by Al/Si pads in a four-terminal configuration for thermal conductivity measurement. Also, dedicated structures for the measurement of the Seebeck coefficient and electrical resistivity were prepared. In this way, the thermoelectric figure of merit of the nanowires could be evaluated. The As-doped nanowires were heavily doped by thermal doping from spin-on-dopant sources, whereas predeposition from POCl3 was utilized for the P-doped nanowires. The thermal conductivity measured on the nanowires appeared to depend on the doping type. The P-doped nanowires showed, for comparable cross-sections, higher thermal conductivity values than As-doped nanowires, most probably because of their finer grain texture, resulting from the inhibition effect that such doping elements have on grain growth during high-temperature annealing.