Thermal Characterization of Au-Si Multilayers Using 3-Omega Method by Sunmi Shin
Explore the thermal conductivity measurement techniques, including the 3-Omega method, for Au-Si multilayers. Learn about the weaknesses of conventional steady-state systems, principles of extracting thermal conductivity, and applications in ultralow thermal conductivity materials. Discover how temperature gradients are analyzed within specimens.
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Presentation Transcript
PHYS 211A Thermal characterization of Au-Si multilayers using 3-omega method Sunmi Shin Materials Science and Engineering Program 1
Conventional steady-state system to measure thermal conductivity Fourier s Law of heat conduction: k = -Q t A DT Q: input power T: temperature difference t: thickness A: cross-sectional area What is the weaknesses? Long thermal equilibrium time Errors due to black body radiation 2
What is 3-omega measurement? Nano lett., 14, 2448-2455 (2014) 3
How to extract thermal conductivity [1] I = I0sin(wt) Apply AC current 2R 2 2R 2 2R=I0 +I0 P = I0sin(wt) [ ] cos(2wt) Heat generates a temperature fluctuation. DT =TDC+ T2wcos(2wt +f) R is influenced by temperature oscillation. R(T)= R(T0)(1+aDT) a =1 dR dT Temperature coefficient of resistance (TCR) R R(T)= R(T0) 1+aTDC+a T2wcos(2wt +f) 4
How to extract thermal conductivity [2] V = IR = I0R0(1+aDTDC)cos(wt)+1 2a DTACcos(wt +f)+1 2a DTACcos(3wt +f) V3w=1 2I0R0aT2w T depends on k. k can be extracted from V3 vs . Slope of the curve on logscale Indicative of k Measured 3 voltage How? 5
Thermal conductivity with 1D heat conduction P = -kAdT2w A=prl Heated region: semi-circle dr dr r r1 T2 = -kpl P dT2w r2 T1 V3w=1 DT2w= -P kpllnr2 2I0R0aT2w r1 3lnf2 V0 r =1 D dR dT f1 q= k = 4p f 4plR0 2(V3w,1-V3w,2) 1/q: thermal penetration depth f: input frequency D: thermal diffusivity of the specimen 3a V0 k = 4plR0S Slope of the curve 6
Application: Au-Si multilayers with ultralow k Highly dissimilar interfaces lower the thermal conductivity. DTR ~ 1.6 DTR ~ 18.7 Nano lett., 14, 2448-2455 (2014) Phy. Rev. B 73, 144301 (2006) Debye temperature ratio (DTR): 3.9 7
Temperature gradient within specimen Heater Film Substrate Film Heater Substrate 8 Nano lett., 14, 2448-2455 (2014)
Measured thermal conductivity of Au-Si multilayers Nano lett., 14, 2448-2455 (2014) 9
Thank you! 10
