Three-terminal semiconductor junction thermoelectric devices: improving performance

A three-terminal thermoelectric device based on a p-i-n semiconductor junction is proposed, where the intrinsic region is mounted onto what is typically a bosonic thermal terminal. Remarkably, the figure of merit of the device is governed also by the energy distribution of the bosons participating in the transport processes, in addition to the electronic. An enhanced figure of merit can be obtained when the relevant distribution is narrow and the electron-boson coupling is strong (such as for optical phonons). We study the conditions for which the figure of merit of the three-terminal junction can be greater than those of the usual thermoelectrical devices made of the same material. A possible setup with a high figure of merit, based on Bi2Te3/Si superlattices, is proposed.