Abstract
We grow and kinetically stabilize the isotropic rocksalt phase of SnSe thin films by alloying SnSe with CaSe. Thin polycrystalline films of the metastable heterostructural alloy Sn1-xCaxSe are synthesized by pulsed laser deposition on amorphous SiO2 over the entire composition range 0 < x < 1. We observe the theoretically-predicted, composition-driven change from a layered, orthorhombic structure to an isotropic, cubic structure near x = 0.18, in reasonable agreement with the theoretical value of x = 0.13 calculated from first principles. The optical band gap is highly non-linear in x and the trend agrees with theory predictions. Compared to the layered end-member SnSe, the isotropic alloy near the orthorhombic-to-rocksalt transition has a p-type electrical resistivity three orders of magnitude lower, and a thermoelectric power factor at least ten times larger. Thus manipulation of the structure of a functional material like SnSe via alloying may provide a new path to enhanced functionality, in this case, improved thermoelectric performance.
Original language | American English |
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Pages (from-to) | 16873-16882 |
Number of pages | 10 |
Journal | Journal of Materials Chemistry A |
Volume | 5 |
Issue number | 32 |
DOIs | |
State | Published - 2017 |
Bibliographical note
Publisher Copyright:© The Royal Society of Chemistry 2017.
NREL Publication Number
- NREL/JA-5K00-70057
Keywords
- polycrystalline
- thermoelectric performance
- thin films