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Thermoelectric modules convert thermal energy into electrical energy and vice versa. At present bismuth telluride is the
most widely commercial used material for thermoelectric energy conversion. There are many applications where bismuth
telluride modules are installed, mainly for refrigeration. However, bismuth telluride as material for energy generation in
large scale has some disadvantages. Its availability is limited, it is hot stable at higher temperatures (>250°C) and
manufacturing cost is relatively high. An alternative material for energy conversion in the future could be silicon. The
technological processing of silicon is well advanced due to the rapid development of microelectronics in recent years.
Silicon is largely available and environmentally friendly. The operating temperature of silicon thermoelectric generators
can be much higher than of bismuth telluride. Today silicon is rarely used as a thermoelectric material because of its high
thermal conductivity. In order to use silicon as an efficient thermoelectric material, it is necessary to reduce its thermal
conductivity, while maintaining high electrical conductivity and high Seebeck coefficient. This can be done by
nanostructuring into arrays of pillars. Fabrication of silicon pillars using ICP-cryogenic dry etching (Inductive Coupled
Plasma) will be described. Their uniform height of the pillars allows simultaneous connecting of all pillars of an array.
The pillars have diameters down to 180 nm and their height was selected between 1 micron and 10 microns.
Measurement of electrical resistance of single silicon pillars will be presented which is done in a scanning electron
microscope (SEM) equipped with nanomanipulators. Furthermore, measurement of thermal conductivity of single pillars
with different diameters using the 3ω method will be shown.
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