On the application of boron and phosphorus heavily doped LPCVD polycrystalline silicon thin films as thermoelectric materials

Even in the metallic regime, heavily doped polycrystalline silicon has high thermopower, but since recently, due its high resistivity combined with high thermal conductivity, silicon was not considered as a possible thermoelectric material. However, various reasons have encouraged investigations on polycrystalline silicon in order to enhance its TE properties. We discuss these reasons and give a short overview of the most promising results and works done in the field. We also present our incipient work on the LPCVD obtained polysilicon thin films annealed in various ways. The main important result we obtained so far is the high thermopower of a Si:B sample: +200 µV/K at room temperature; much higher than predicted for the common metals and the same as of Bi
2
Te
3
, the only thermoelectric material commercially used nowadays.