  Single-crystalline silicon is well known to be a poor thermoelectric material
due to its high thermal conductivity. Most excellent research has focused on
ways to decrease its thermal conductivity while retaining acceptably large
power factors (PFs). Less effort has been spent to enhance the PF in poly and
nanocrystalline silicon, instead. Here we show that in boron-hyperdoped
nanocrystalline thin films PF may be increased up to 33 mW K$^{-2}$m$^{-1}$ at
300 K when hydrogen embedded in the film during deposition is removed. The
result makes nanocrystalline Si a realistic competitor of Bi$_2$Te$_3$ for
low-temperature heat harvesting, also due to its greater geo-availability and
lower cost.
