Abstract
In this article, the authors reported a theoretical study of structural and electronic properties of PbTe inclusions in CdTe matrix as well as CdTe nano-clusters in PbTe matrix. The structural properties are studied by ab initio methods. A tight-binding model is constructed to calculate the electron density of states (DOS) of the systems. In contrast to the ab initio methods, the latter allows studying nanostructures with diameters comparable to the real ones. The calculations show that both kinds of inclusions lead to changes of the DOS of the carriers near the Fermi level, which may affect optical, electrical and thermoelectric properties of the material. These changes depend on the size, shape, and concentration of inclusions.
Highlights
Using ab initio and tight-binding methods, the density of states (DOS) for three kinds of PbTe-CdTe pseudo-binary systems is studied, i.e. PbTe NWs embedded in CdTe matrix; the CdTe A-quantum dot (QD); and A-NWs in PbTe matrix
The results of our calculations show that quantum confinement of PbTe wires leads to 1 D sub-bands and changes dramatically the derivative of the electron DOS at the Fermi atomic positions
In all following figures, the energy zero in the valence and conduction bands was put at the energy corresponding to Fermi level for carrier concentration p(n) = 1019 cm-3
Summary
This material is widely used for mid-infrared lasers and detectors [1,2]. PbTe has attracted a lot of interest due to its thermoelectric properties, and the material is used for small-scale cooling applications as well as for power generation in remote areas [3,4]. The efficiency of a thermoelectric device is described by the dimensionless thermoelectric figure-of-merit parameter ZT. In the currently used thermoelectric devices based on PbTe, Si-Ge, or Bi2Te3 alloys, ZT reaches 1. This value imposes limitation to possible applications of semiconductor thermoelectric devices, and a lot of effort is put to increase the parameter
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