  Tellurium (Te) is an intrinsically p-type doped narrow bandgap semiconductor
with excellent electrical conductivity and low thermal conductivity. Bulk
trigonal Te has been theoretically predicted and experimentally demonstrated to
be an outstanding thermoelectric material with high value of thermoelectric
figure-of-merit ZT. In view of the recent progress in developing synthesis
route of two-dimensional (2D) tellurium thin films as well as the growing trend
of exploiting nanostructures as thermoelectric devices, here for the first time
we report excellent thermoelectric performance of tellurium nanofilms, with
room temperature power factor of 31.7 {\mu}Wcm-1K-2 and ZT value of 0.63. To
further enhance the efficiency of harvesting thermoelectric power in nanofilm
devices, thermoelectrical current mapping was performed with a laser as a
heating source, and we found high work function metals such as palladium can
form rare accumulation-type metal-to-semiconductor contacts to 2D Te, which
allows thermoelectrically generated carriers to be collected more efficiently.
High-performance thermoelectric 2D Te devices have broad applications as energy
harvesting devices or nanoscale Peltier coolers in microsystems.
