Thermal Transport in Silicon Nanowires at High Temperature
up to 700 K
Jaeho Lee
Woochul Lee
Jongwoo Lim
Yi Yu
Qiao Kong
Jeffrey J. Urban
Peidong Yang
10.1021/acs.nanolett.6b00956.s001
https://acs.figshare.com/articles/journal_contribution/Thermal_Transport_in_Silicon_Nanowires_at_High_Temperature_up_to_700_K/3407575
Thermal transport in silicon nanowires
has captured the attention
of scientists for understanding phonon transport at the nanoscale,
and the thermoelectric figure-of-merit (ZT) reported in rough nanowires
has inspired engineers to develop cost-effective waste heat recovery
systems. Thermoelectric generators composed of silicon target high-temperature
applications due to improved efficiency beyond 550 K. However, there
have been no studies of thermal transport in silicon nanowires beyond
room temperature. High-temperature measurements also enable studies
of unanswered questions regarding the impact of surface boundaries
and varying mode contributions as the highest vibrational modes are
activated (Debye temperature of silicon is 645 K). Here, we develop
a technique to investigate thermal transport in nanowires up to 700
K. Our thermal conductivity measurements on smooth silicon nanowires
show the classical diameter dependence from 40 to 120 nm. In conjunction
with Boltzmann transport equation, we also probe an increasing contribution
of high-frequency phonons (optical phonons) in smooth silicon nanowires
as the diameter decreases and the temperature increases. Thermal conductivity
of rough silicon nanowires is significantly reduced throughout the
temperature range, demonstrating a potential for efficient thermoelectric
generation (e.g., ZT = 1 at 700 K).
2016-05-31 17:20:49
silicon nanowires show
silicon nanowires
waste heat recovery systems
ZT
700 K
Boltzmann transport equation
understanding phonon transport