  The observation that the thermal conductivity of single-crystalline silicon
nanowires with diameter on the length scale of 25 nm is lower than that of bulk
material by two orders of magnitude has attracted the interest onto silicon as
a potentially effective thermoelectric material. However, the potential
interest has a hope of transforming in a practical interest only if
poly-crystalline silicon can replace single crystalline silicon and the
preparation of nanowires does not involve any advanced photolithography. In
this work we show that a technique, based on the controlled etching and filling
of recessed regions and employing standard photolithography and
deposition-etching methods, succeeds in the preparation of poly-crystalline
silicon nanowires (with diameter of 25 nm and length on the centimetre scale)
at a linear density of 3E6 cm^-1.
