ABSTRACT
As proposed by Dresselhaus and colleagues in the early 1990s [10-12], materials with lower-dimensional characteristics, such as 2D superlattices (SLs), 1D nanowires, and 0D quantum dots, may possess signicantly enhanced TE properties and have been intensively studied to achieve (1) reduction in thermal conductivity (e.g., by all-scale hierarchical phonon scattering [13]) and (2) enhancement in power factor (via formation of band resonant states [14], quantum connement [15], modulation doping [16], energy ltering [17], and other novel mechanisms [18]). A spectacular ZT ~ 2.4 at 300 K was claimed in 2001 for p-type Bi2Te3/Sb2Te3 SLs [19]. Despite the fact that such impressive ZT values on SLs have never been reproduced by intense efforts worldwide [20], the possibility of enhancing TE performance by decoupling electronic and thermal transport processes with reduced dimensionality has boosted the fabrication of tetradymite-type TE lms and SLs.
