IWCE 2015 presentation. Engineering silicon at the nanoscale paves the way to new applications of this cheap, abundant, and technologically and environmentally friendly material. Transistors in nanoelectronics have reached the 10 nm size limit, implying very high density but also critical issues regarding heat dissipation. The fabrication of crystalline silicon nanowires and ultra-thin silicon membranes with characteristic size of the order of 10 nm or less gives rise to thermal and electronic properties that enable the use of silicon as a low-temperature thermoelectric material for sensing and energy harvesting. At the same time, nanowires, thin films and membranes can be potentially employed as the basic platform to develop nano-resonators, phononic crystals or metamaterials, with a variety of applications. It follows that an efficient exploitation of nanoscale silicon stems from a better understanding of its electronic, phononic and thermal properties, and especially on the impact of confinement and surfaces.
In this work we unravel the effect of dimensionality reduction and the prominent role of surface structure and surface resonances in tuning the phonon dispersion relations and the thermal conductivity of silicon nanostructures, including ultrathin membranes ,  and silicon nanowires , . In particular we show how surface roughness and surface oxidation affect phonon transport in silicon nanostructures, reducing dramatically their thermal conductivity 1. We also compute the electronic properties of silicon membranes as a function of thickness and the concentration of dopants, identifying the conditions that maximize the thermoelectric figure of merit, both for periodic extended materials and for open systems in device configuration.
In collaboration with Daniele Selli, Shiyun Xiong, Claudia Mangold, Sanghamitra Neogi, Max Planck Institute for Polymer Research, Ackermannweg, Germany. This work has been supported by the European Commission FP7-ENERGY-FET project MERGING, contract number 309150.
-  S. Neogi and D. Donadio, Eur. Phys. J. B 88, 73 (2015).
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-  D. Donadio and G. Galli, Nano Lett 10, 847 (2010).
-  I. Duchemin and D. Donadio, Appl Phys Lett 100, 223107 (2012).
Cite this work
Researchers should cite this work as follows:
Donadio, Davide, "Ultra-Thin Silicon Membranes and Nanowires as Nanophononic and Thermoelectric Devices," in Computational Electronics (IWCE) 2015 International Workshop on, DOI: Not available in IEEE Xplore digital library. Full Website Here
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