Enhanced Thermoelectric Properties of Silicon via Nanostructuring

抄録

The effectiveness of thermoelectric (TE) materials at converting heat gradients into electricity, and vice versa, is quantified by the dimensionless figure of merit, ZT. Current TE materials, such as Bi₂Te₃ and PbTe, have ZT values of approximately 1, but contain highly toxic and/or rare elements, which limits their widespread use. However, Si is a non-toxic, inexpensive, and abundant element. Even though bulk Si exhibits good electrical properties, its lattice thermal conductivity (κ_lat) is high (>100 Wm⁻¹ K⁻¹), which results in a ZT value of approximately 0.01 at room temperature. If it were possible to lower the κ_lat of Si without altering the electrical properties, Si would be an ideal TE material. These changes can be realized by nanostructuring Si. In this review, we discuss the recent achievements in the enhancement of the TE properties of Si via nanostructuring. Based on these recent results, we also indicate some potential topics to investigate to enhance the TE properties of Si further.