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Silicon nanowires (Si NWs) have been implemented in microfabricated structures to develop planar thermoelectric microgenerators (�TEGs) monolithically integrated in silicon. The purpose is to convert into electric energy the heat flow originated by thermal gradients naturally present in the environment. The compatibility of typical microfabrication technologies and the vapor-liquid-solid growth mechanism (VLS) for growing silicon nanowires has been evaluated. Low-thermal mass suspended structures have been designed, simulated and microfabricated on Silicon On Insulator substrates to passively generate thermal gradients and operate as microgenerators using silicon nanowires as thermoelectric material. Electrical measurements to evaluate the connectivity of the nanowires and thermoreflectance imaging to determine the heat transfer along the device have been employed.

Silicon nanowires present outstanding properties for electronics, energy, and environmental monitoring applications. However, their integration into microelectromechanical systems (MEMS) is a major issue so far due to low compatibility with mainstream technology, which complicates patterning and controlled morphology. This work addresses the growth of 〈111〉 aligned silicon nanowire arrays fully integrated into standard MEMS processing by means of the chemical vapor deposition-vapor liquid solid method (CVD-VLS) using silane as a precursor. A reinterpretation of the galvanic displacement method is presented for selectively depositing gold nanoparticles of controlled size and shape. Moreover, a comprehensive analysis of the effects of synthesis temperature and pressure on the growth rate and alignment of nanowires is presented for the most common silicon precursor, i.e., silane. Compared with previously reported protocols, the redefined galvanic displacement together with a silane-based CVD-VLS growth methodology provides a more standard and low-temperature (<650 °C) synthesis scheme and a compatible route to reliably grow Si nanowires in MEMS for advanced applications.