Fig. 5.

Enhancement of zT of p-type SnTe with different carrier concentrations at 300 K due to the MFP filtering effect. The black open circles are bulk zT without boundary scattering. The green, red, and blue open circles are zT calculated under boundary scattering when the characteristic lengths l_GB = 100 nm, 30 nm, and 10 nm are, respectively, applied. The solid circles are experimental values of bulk SnTe by Zhou et al. (51). The shaded region shows the carrier concentration between 1.0 × 10²⁰ cm⁻³ and 6.0 × 10²⁰ cm⁻³, which is the typical regime that can achieve high zT in experiments.