Arun Majumdar, UC Berkeley

Challenges and Opportunities in Thermoelectric Energy Conversion

Arun Majumdar

Department of Mechanical EngineeringUniversity of California, Berkeley

Materials Sciences DivisionLawrence Berkeley Lab

DOE, NSF, ONR, NASA

Arun Majumdar, UC Berkeley

Thermoelectricity and Energy Conversion

ab

V

T1 T2

aSeebeck Coefficient, S = V/∆T

Peltier Coefficient, π = Q/I=ST

pnpn

R

Qin

Qout

Qin

Tcold

Thot

pnpn

QoutI

V

Arun Majumdar, UC Berkeley

Thermoelectric Figure of Merit

Arun Majumdar, UC Berkeley

Arun Majumdar, UC Berkeley

Arun Majumdar, UC Berkeley

Courtesy: Gang Chen

Arun Majumdar, UC Berkeley

Origins of Thermoelectricity

Arun Majumdar, UC Berkeley

Effect of Nanostructuring on S2σ

(Dresselhaus et al., 1993)

Arun Majumdar, UC Berkeley

Majumdar, Science 303, 777 (2004)

PbSeTe/PbTe QD Superlattices

Harman et al., Science 297, 2229 (2002)

AgPb18SbTe20ZT = 2 @ 800K

AgSb rich

Hsu et al., Science 303, 818 (2004)

kTSZT σ2

=

Venkatasubramanian et al. Nature 413, 597 (2001)

Bi2Te3/Sb2Te3 Superlattices2.5-25nm

kbulk = 0.49 W/m-Kkns = 0.22 W/m-K

Arun Majumdar, UC Berkeley

k [W

/m-K

]

A B

Alloy Limit

Alloy limit of thermal conductivity in crystalline materials!

Arun Majumdar, UC Berkeley

Li et al., Appl Phys Lett 83, 3186 (2003)

Deyu Li, Yiying Wu, Rong Fan, Peidong Yang

Nanowire

Si/SiGe superlattice nanowires

Arun Majumdar, UC Berkeley

ErAs Nanostructures Embedded in InGaAs

Arun Majumdar, UC Berkeley

InGaAs

ErAs/InGaAs

Woochul Kim, Pramod Reddy, Josh Zide, Art Gossard

Below Alloy Limit!

Arun Majumdar, UC Berkeley

k =

d

dTeb ω( )Planck BB1 2 3 v ω( )

Speed{ l ω( )

MeanFreePath{ dω

0

ωmax

∫⎡

⎣

⎢ ⎢

⎤

⎦

⎥ ⎥

Frequency, ω ωmax

eb

v

Atoms/Alloys

Nanostructures

Phonon Scattering

Hypothesis

Arun Majumdar, UC Berkeley

Courtesy: Ed Croke, Hughes Res. Lab. for materials

Si-Ge Superlattices

Arun Majumdar, UC Berkeley

Cathode

Barrier

Anode

Metallic contact for

top connection

100 microns

Courtesy: John Bowers (UCSB); Ali Shakouri (UCSC)

SEM Picture of Thin Film Coolers

Arun Majumdar, UC Berkeley

X. Fan, G. Zeng, C. LaBounty, E.Croke, C. Ahn, J.E. Bowers, A. Shakouri, “SiGeC/Si superlattice micro cooler,” Applied Physics Lett., Vol. 78, No.11, 12

March 2001.Featured in Nature Science Update, Physics Today, AIP April 2001

n-Si/SiGeC Superlattice Micro Cooler

Arun Majumdar, UC Berkeley

G. Zeng, X. Fan, C. LaBounty, J.E. Bowers, E.Croke, J. Christofferson, D. Vashaee, A. Shakouri, “Direct Measurement of Cooling Power Density for Thin Film Suplerlattice Micro Coolers,” submitted to APL 2002.

Micro Refrigerator Integrated with Thin-Film Heater

Arun Majumdar, UC Berkeley

Localized control of temperature on the chip.

InP-based Micro Refrigerator & Micro Heater

Arun Majumdar, UC Berkeley

Nanowire Array Composites and Devices

2 µm

200 nm

Majumdar Lab, UC Berkeley

Arun Majumdar, UC Berkeley

Majumdar, Science 303, 777 (2004)