Volume 117, Number 2, January 2017
|Number of page(s)||6|
|Section||Condensed Matter: Electronic Structure, Electrical, Magnetic and Optical Properties|
|Published online||10 March 2017|
Spectroscopic evidence for temperature-dependent convergence of light- and heavy-hole valence bands of PbQ (Q = Te, Se, S)
1 Department of Physics, University of Virginia - Charlottesville, VA 22904, USA
2 Department of Chemistry, Northwestern University - Evanston, IL 60208, USA
3 Materials Science Division, Argonne National Laboratory - Argonne, IL 60439, USA
Received: 27 November 2016
Accepted: 21 February 2017
We have conducted a temperature-dependent angle-resolved photoemission spectroscopy (ARPES) study of the electronic structures of PbTe, PbSe and PbS. Our ARPES data provide direct evidence for the light-hole upper valence bands (UVBs) and hitherto undetected heavy-hole lower valence bands (LVBs) in these materials. An unusual temperature-dependent relative movement between these bands leads to a monotonic decrease in the energy separation between their maxima with increasing temperature, which is known as band convergence and has long been believed to be the driving factor behind extraordinary thermoelectric performances of these compounds at elevated temperatures.
PACS: 72.20.Pa – Thermoelectric and thermomagnetic effects / 71.20.-b – Electron density of states and band structure of crystalline solids / 71.18.+y – Fermi surface: calculations and measurements; effective mass, g factor
© EPLA, 2017
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