Scalable Silicon Nanostructuring for Thermoelectric Applications

• Published in: Journal of electronic materials 2013-07, Vol.42 (7), p.2114-2118
• Main Authors: Koukharenko, E., Boden, S. A., Platzek, D., Bagnall, D. M., White, N. M.
• Format: Article
• Language: English
• Subjects: Applied sciences; Characterization and Evaluation of Materials; Chemistry and Materials Science; Condensed matter: electronic structure, electrical, magnetic, and optical properties; Condensed matter: structure, mechanical and thermal properties; Conductivity phenomena in semiconductors and insulators; Electricity generation; Electronic structure and electrical properties of surfaces, interfaces, thin films and low-dimensional structures; Electronic transport in condensed matter; Electronic transport phenomena in thin films and low-dimensional structures; Electronics; Electronics and Microelectronics; Exact sciences and technology; Instrumentation; Materials Science; Nanostructured materials; Optical and Electronic Materials; Physics; Semiconductor doping; Semiconductor electronics. Microelectronics. Optoelectronics. Solid state devices; Silicon; Solid State Physics; Structure and morphology; thickness; Surfaces and interfaces; thin films and whiskers (structure and nonelectronic properties); Thermal energy; Thermoelectric and thermomagnetic effects; Thermoelectric effects; Thermoelectric, pyroelectric devices, etc; Thin film structure and morphology
• ISSN: 0361-5235; 1543-186X
• DOI: 10.1007/s11664-013-2539-6

The current limitations of commercially available thermoelectric (TE) generators include their incompatibility with human body applications due to the toxicity of commonly used alloys and possible future shortage of raw materials (Bi-Sb-Te and Se). In this respect, exploiting silicon as an environmentally friendly candidate for thermoelectric applications is a promising alternative since it is an abundant, ecofriendly semiconductor for which there already exists an infrastructure for low-cost and high-yield processing. Contrary to the existing approaches, where n / p -legs were either heavily doped to an optimal carrier concentration of 10 19  cm −3 or morphologically modified by increasing their roughness, in this work improved thermoelectric performance was achieved in smooth silicon nanostructures with low doping concentration (1.5 × 10 15 cm −3 ). Scalable, highly reproducible e-beam lithographies, which are compatible with nanoimprint and followed by deep reactive-ion etching (DRIE), were employed to produce arrays of regularly spaced nanopillars of 400 nm height with diameters varying from 140 nm to 300 nm. A potential Seebeck microprobe (PSM) was used to measure the Seebeck coefficients of such nanostructures. This resulted in values ranging from −75  μ V/K to −120  μ V/K for n -type and 100  μ V/K to 140  μ V/K for p -type, which are significant improvements over previously reported data.