evaluation systems of thermoelectric properties of ......evaluation systems of thermoelectric...
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Evaluation systems of thermoelectric properties of electrochemically deposited
Bi2Te3 films and nanowire arrays
Yoshikazu Shinohara*, Marisol Martin-Gonzalez**
* National Institute for Materials Science, Japan ** Instituto Microelectrónica de Madrid, Spain
The state of arts of thermoelectric materials
ドーピング制御
化合物組成比探索
人工超格子
移動度大の
化合物半導体
ラットリング
スクッテルダイト系
クラスレート系
ハーフホイスラ系
f電子強相関系
多結晶体制御
固溶体系
量子効果
性能指数 S:ゼーベック係数(µV/K)
ρ:比抵抗(Ωm)κ:熱伝導率(W/Km)κρ
2SZ =
ZTSrTiO3
PbSeTe
Bi2Te3/Sb2Te3
材料系
↑プロセス
Film
Bulk
Superlattice Quantum effect Ratlling Poly-crystal Doping Composition
Process control Materials
Com
poun
d se
mic
ondu
ctor
s S
olid
sol
utio
ns
Suk
uttle
dite
C
lath
rate
H
alf-w
hist
ler
Stro
ng c
orel
late
d
κσ TSZT
2
=S:Seebeck coefficient(µV/K) σ:Electrical conductivity (S/m) κ:Thermal conductivity(W/Km) T: Absolute temperature (K)
Dimensionless figure-of-merit
Dilemma between nanotechnology and macro application(waste heat recovery)
Nano technoplogy Micro technology Macro technology
Physics
Computer Science
Material Science
Material Process Try and Error
Device Process
How to overcome the dilemma?
Research Field: “Nanoscience and New Materials for Environmental Challenges”
Cooperative Research Project (2010-2012)
First steps towards the integration of nanowire arrays on practical thermoelectric devices for Energy applications -NANOTHERMA-
FY2009 Strategic Japanese-Spanish Cooperative Program
Goal (1) Developing thermoelectric technologies of nanowire arrays. (2) Finding a hint for a breakthrough of thermoelectric performance.
Synthesis Technology Measurement Technology + Bi-Te nanowire array Quantitative evaluation
Project Leader: Dr. M. Martin-Gonzalez Project Leader: Dr. Y. Shinohara
Instituto Microelectrónica de Madrid National Institute for Materials Science
Spain Japan
Exchange of technology, idea and researchers
Good cooperation in the near future
Samples
Not Annealed 423 K/1 hr
473 K/1 hr 573 K/1 hr
1 μm×20000
Bi2Te3 film Bi2Te3 nanowire array
1.3 cmAlumina template.
120nmφ
Experimental Setup for films (in-plane direction)
Measurement of Seebeck coefficient for Standard sample (Pt wire)
The measured value agrees well with the reference value of -5.24µV/K
All resistance measured with probe distance ~ 5 mm
Seebeck coefficient (µV/K) Electrical conductivity (S/cm)
Samples
Experiments
As prepared 423 K 473 K 573 K Substrate Si/Ti/Au
Measured resistance
0.23 Ω 0.14 Ω 0.15 Ω 0.28 Ω 1.81 Ω
Seebeck coefficient
-4.57 µV/K -6.58 µV/K -6.36 µV/K -9.33 µV/K -104.47 µV/K
(273K)
:Heat sink
:Sample stage with thermocouple
:Peltier heater
:Sample
Fig. Sample stage with thermocouple
Thermocouples: T-type 0.127 mmφ Peltier heater: 4cm×4cm Max. input 6W
Experimental Setup for nanowire array (thickness direction)
Seebeck coefficient Standard measurement using Si wafer (thickness 500 μm)
0.0
0.5
1.0
1.5
2.0
0 20 40 60 80 100 120 140
y = 0.012143 + 0.016536x R= 0.99984 Tem
pera
ture
def
eren
ce /
KInput power of heater x / mW
Fig. Temperature difference as a function of input power.
Fig. Home-made apparatus of nanowire array measurement
T
empe
ratu
re d
iffer
ence
/K
-600
-450
-300
-150
0
0 0.5 1 1.5 2 2.5 3
y = -5.9169 - 186.38x R= 0.99997
Tot
al th
erm
oele
ctri
c po
wer
/ μ
VDelta T / K
-600
-500
-400
-300
-200
-100
0
0 0.5 1 1.5 2 2.5 3
Tot
al th
erm
oele
ctri
c po
wer
/ μ
V
Delta T / K
⊿T ⊿T
Ssi=-179.96 μVK-1
Seebeck coefficient of standard measurement using Si wafer
Fig. Relationship between deltaT and total thermoelectric power(TPtotal) in thickness direction of Si.
Fig. Relationship between deltaT and total thermoelectric power(TPtotal) in planar direction of Si.
Good matching between in-plane and thickness setups
In-plane setup Thickness setup
T
herm
oele
ctro
mot
ive
forc
e /µ
V
T
herm
oele
ctro
mot
ive
forc
e /µ
V
Ssi=-184.52 μVK-1
Seebeck coefficient and electrical conductivity of Bi2Te3 nanowire array
0
5
10
15
20
25
0 5 10 15 20 25 30 35
The
rmoe
lect
ric
pow
er /
μV
Input power of heater / mW
厚さ60 μm
Fig. Thermoelectric power as a functionof input power.
S=12µV/K
T
herm
oele
ctro
mot
ive
forc
e /µ
V
Seebeck coefficient of films
0
5 10-5
1 10-4
2 10-4
2 10-4
0 5 10-6 1 10-5 1.5 10-5 2 10-5 2.5 10-5
y = 3.5e-7 + 7.708x R= 0.99991
Vol
tage
/ V
Current / A
141079.1 −−×= Scmσ
Fig. I-V curve of nanowire-array.
1.3 cmAlumina template.
Good cooperation in the near future
Research Field: “Nanoscience and New Materials for Environmental Challenges”
Cooperative Research Project (2009-2012)
First steps towards the integration of nanowire arrays on practical thermoelectric devices for Energy applications -NANOTHERMA-
FY2009 Strategic Japanese-Spanish Cooperative Program
Synthesis Technology Measurement Technology + Bi-Te nanowire array Quantitative evaluation
Project Leader: Dr. M. Martin-Gonzalez Project Leader: Dr. Y. Shinohara
Instituto Microelectrónica de Madrid National Institute for Materials Science
Spain Japan
Exchange of technology, idea and researchers
Good results by good collaboration between Japan and Spain
Acknowledgment
• Dr. Yukihiro Isoda • Dr. BISWAPRIYA DEB • Dr. Hiroshi Kawakami • Dr. Olga C. Calero • Dr. Pablo Díaz Chao • Ms. Begona A. Mayor
(Best poster award at the Workshop at Toledo in 2011)
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