Development of High-efficiency Thermoelectric Devices Using Nanowires Jong Wook Roh and Woo Young Lee Department of Materials Science and Engineering, Yonsei University 1. 21.. (,,,, ). (thermoelectric effect) Seebeck (1821 ) Peltier (1843 ).( 1 ) (energy consumption) (energy generation),,,.,,, IT, BT.( 2) 1. (a) Seebeck (b) Peltier 33
2. 10%,,... 2. 1821 T. J. Seebeck, Abram Ioffe Seebeck 100 4%. (thermoelectric figure of merit, ZT m ). S Seebeck, (electrical conductivity), k (thermal 3. (Ref.[5]) conductivity). (parameter) (carrier concentration).., 1950 Bi 2 Te 3 (ZT m 1) 2000.( 3) 1993 MIT Dresselhaus power factor(s 2 ) 4 1,2). Dresselhaus (quantum confinement effect), power factor (phonon) (scattering source) Seebeck,.( 5) 2001 RTI(Research 34
.. Bi 1. 3. 4. n-type Bi (Ref.[6, 7]) 5. (a) (b) Triangle Institute, ) Venkatasubramanian Bi 2 Te 3 /Sb 2 Te 3 ZT m =2.4 (T m =300K) 3), MIT Harman PbSeTe 1.6. 4) Dresselhaus power factor (heat carrier), (1) MIT Dresselhaus, (2 ) (1 )., 2000 NASA,,, (DOE: Department of Energy) 3,000 2009. MIT, Caltech, U.C. Berkeley. Bi. 8) MIT Dresselhaus 1993 Bi. Dresselhaus semiclassical transport model band structure model 10nm Bi. 6) (pressure injection method) Bi, 65nm Bi - (semimetal to semiconductor 35
transition). 9,10) Bi, Bi Bi array 2 Bi.( 6) 2006 Caltech Heath Bi Seebeck suspended device 72nm Bi Seebeck 25 V/K. Bi Seebeck Bi(Seebeck : 50~100 V/K), - (semimetal-tosemiconductor transition). 11) Si, (ZT m =0.01). 2008 Berkeley Yang Caltech Heath Nature Si. Si,. Caltech Heath Si 200K 1. 12) Berkeley 6. Dresselhaus (MIT) (a) Bi array (b) Bi array (Ref. [9]) 7. (a) Heath polycrystalline Bi (b) Seebeck (Ref.[11]) 36
. core/shell. Li 10 (a) Te/Bi 2 Te 3 core/shell two-step solution phase 8. Yang (U. C. Berkeley) rough surface Si (a) TEM (b) Si (c) TEM (d), Te/Bi 2 Te 3 core/shell bulk composite., 0.55W/ m-k. 14) 2003 Berkeley Majumdar Si/SiGe microsuspended device, phonon alloy scattering. 15) 9. Si (Ref.[12]) Yang rough surface Si, 0.8W/m-K Si 100,. 13) Yang Si (nano-ribbon), phonon 300K 1.14. Yang rough Si Si 10. (a) Te/Bi 2 Te 3 core/shell TEM (b) Te/Bi 2 Te 3 core/shell Seebeck 37
(2) (ZT~0.8),, LG,. In 4 Se 3-705K 1.48 KIST,, Bi 2 Te 3 2. 16) ETRI top-down 50nm n-type Si - 118µV/K Seebeck. 1,. Bi Bi Bi. 10) Si/SiO 2 Bi Bi (thermodynamic driving force) Bi. Bi aspect ratio.( 11) 120nm Bi 76900cm 2 /Vs, 1.35 m. 17,18) (stress-induced method) whisker,. 19,20) Bi 2 Te 3 compound semiconductor. 21) Bi (nano particles), 11. (a) Bi (b) Bi (c) Bi 38
Bi 50.. array,. Bi suspended micro-device Bi Seebeck. 13 (a) suspended micro- 12. Bi suspended micro-device (a) (b) (c) Bi 13. Seebeck (a) (b) 39
14. (a) All-in-one MEMS (b) All-in-one MEMS device. 22,23) suspended micro-device SiN x heater Bi, sensing coil (thermal conductance). membrane (thermal resistance) dual-beam Focused ion beam thermal contact 13 (b). Bi 23,24), 98nm Bi 0.8W/m-K Bi( : 8W/m-K) 10. Seebeck Seebeck. 25) 14 (a) Bi Seebeck. micro heater Joule heat (thermal gradient), 4 (4-pointelectrode). 120nm Bi Seebeck 70 V/K, Bi Seebeck. Seebeck. Allin-one MEMS(micro-electromechanical systems), Seebeck. 14 All-in-one MEMS Seebeck, suspended structure, 4. MEMS 4 thermal contact ohmic contact plasma etching. All-in-one MEMS membrane, plasma etching Bi. thermal contact ohmic contact 40
, Seebeck., array.. p-type n-type. (parylene),., (glass transition temperature) 90 290.. 4.. 2000,.,,,.,.,,.. 15. 2009 (2009-0093823). 41
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