**Thermal conductivity of hexagonal Si and hexagonal Si nanowires from
first-principles**

M Raya-Moreno and H Aramberri and JA Seijas-Bellido and X Cartoixa and R Rurali, APPLIED PHYSICS LETTERS, 111, 032107 (2017).

DOI: 10.1063/1.4985278

We calculate the thermal conductivity, kappa, of the recently
synthesized hexagonal diamond (lonsdaleite) Si using first-principles
calculations and solving the Boltzmann Transport Equation. We find
values of kappa which are around 40% lower than in the common cubic
diamond polytype of Si. The trend is similar for **111** Si nanowires,
with reductions of the thermal conductivity that are even larger than in
the bulk in some diameter range. The Raman active modes are identified,
and the role of mid-frequency optical phonons that arise as a
consequence of the reduced symmetry of the hexagonal lattice is
discussed. We also show briefly that popular classic potentials used in
molecular dynamics might not be suited to describe hexagonal polytypes,
discussing the case of the Tersoff potential. Published by AIP
Publishing.

Return to Publications page