Structural complexity and the metal-to-semiconductor transition in lead telluride

Abstract

Lead chalcogenides are known for their thermoelectric properties since the first work of Thomas Seebeck on the discovery of this phenomenon. Yet, the electronic properties of lead telluride are still of interest due to the incomplete understanding of the metal-to-semiconductor transition at temperatures around 230 °C. Here, a temperature-dependent atomic-resolution transmission electron microscopy study performed on a single crystal of lead telluride reveals structural reasons for this electronic transition. Below the transition temperature, the formation of a dislocation network due to shifts of the NaCl-like atomic slabs perpendicular to {100} was observed. The local structure modification leads to the appearance of in-gap electronic states and causes metal-like electronic transport behavior. The dislocation network disappears with increasing temperature, yielding semiconductor-like electrical conductivity, and re-appears after cooling to room temperature restoring the metal-like behavior. The structural defects coupled to the ordering of stereochemically active lone pairs of lead atoms are discussed in the context of dislocations' formation.

Improved High‐Temperature Material Stability and Mechanical Properties While Maintaining a High Figure of Merit in Nanostructured p‐Type PbTe‐Based Thermoelectric Elements

“…[ 37 ] Moreover, a recent in‐situ temperature‐dependent transmission electron microscopy study of defects in single crystals proposed healing and new formation of dislocations an alternative origin of the hysteresis in the electrical resistivity observed in p‐type PbTe. [ 57 ]…”

“…[37] Moreover, a recent in-situ temperature-dependent transmission electron microscopy study of defects in single crystals proposed healing and new formation of dislocations an alternative origin of the hysteresis in the electrical resistivity observed in p-type PbTe. [57] The power factor S 2 ρ −1 of n-type Pb 0.98 Ga 0.02 Te decreases from ≈3.5 mW m −1 K −2 at 300 K to ≈1.1 mW m −1 K −2 at 900 K. S 2 ρ −1 of p-type Pb 0.973 Na 0.02 Ge 0.007 Te increases from ≈1.5 mW m −1 K −2 at 300 K to ≈3.0 mW m −1 K −2 at 500 K and stays almost constant during the heating to 900 K (Figure 3c). The S 2 ρ −1 of p-type Pb 0.953 Na 0.04 Ge 0.007 Te increases from ≈0.7 mW m −1 K −2 at 300 K to ≈3.3 mW m −1 K −2 at 700 K, exceeding the peak S 2 ρ −1 of the lower Na content Pb 0.973 Na 0.02 Ge 0.007 Te.…”

STEM Tools for Semiconductor Characterization: Beyond High-Resolution Imaging

“…Remarkably interesting is the fact that accessing the materials structure at different experimental conditions brings the chance to explore metastable phases or phase-transition phenomena. As an example, recently published in situ STEM measurements address the structural origin of the metal-to-semiconductor transition observed in PbTe [ 92 ].…”