ABSTRACT
This chapter discusses thermoelectric properties of individual quintuples and stacks of the graphene-like exfoliated single-crystal quasi-two-dimensional Bi2Te3 films. It shows that ZT in such “pseudo-superlattices” of the stacked films can be substantially increased via reduction of the in-plane and cross-plane thermal conductivity with simultaneously preserved good electrical properties in the films with smooth interfaces. The improvement of thermoelectric properties via phonon engineering also can be achieved in thin films or nanowires with the thickness of just few atomic layers and high quality of interfaces. The epitaxially grown films have to be lattice matched to the substrate, which leads to a small acoustic impedance mismatch and, as a result, the absence of strong confinement effects for the acoustic phonons. The exfoliated atomically thin films have nearly infinite confining potential barriers for both electrons as holes as well as for acoustic phonons, which carry the heat.
