Precise control of thermal conductivity at the nanoscale through individual phonon-scattering barriers.
The ability to precisely control the thermal conductivity (kappa) of a material is fundamental in the development of on-chip heat management or energy conversion applications. Nanostructuring permits a marked reduction of kappa of single-crystalline materials, as recently demonstrated for silicon nanowires. However, silicon-based nanostructured materials with extremely low kappa are not limited to nanowires. By engineering a set of individual phonon-scattering nanodot barriers we have accurately tailored the thermal conductivity of a single-crystalline SiGe material in spatially defined regions as short as approximately 15 nm. Single-barrier thermal resistances between 2 and 4 x 10(-9) m(2) K W(-1) were attained, resulting in a room-temperature kappa down to about 0.9 W m(-1) K(-1), in multilayered structures with as little as five barriers. Such low thermal conductivity is compatible with a totally diffuse mismatch model for the barriers, and it is well below the amorphous limit. The results are in agreement with atomistic Green's function simulations.
Pernot
G
G
CPMOH, Université Bordeaux-CNRS, 351 cours de la Libération, 33405 Talence, France.
Stoffel
M
M
Savic
I
I
Pezzoli
F
F
Chen
P
P
Savelli
G
G
Jacquot
A
A
Schumann
J
J
Denker
U
U
Mönch
I
I
Deneke
Ch
Ch
Schmidt
O G
OG
Rampnoux
J M
JM
Wang
S
S
Plissonnier
M
M
Rastelli
A
A
Dilhaire
S
S
Mingo
N
N