Samuel Huberman
Massachusetts Institute of Technology
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Featured researches published by Samuel Huberman.
Physical Review Letters | 2015
Bolin Liao; Bo Qiu; Jiawei Zhou; Samuel Huberman; Keivan Esfarjani; Gang Chen
The electron-phonon interaction is well known to create major resistance to electron transport in metals and semiconductors, whereas fewer studies are directed to its effect on phonon transport, especially in semiconductors. We calculate the phonon lifetimes due to scattering with electrons (or holes), combine them with the intrinsic lifetimes due to the anharmonic phonon-phonon interaction, all from first principles, and evaluate the effect of the electron-phonon interaction on the lattice thermal conductivity of silicon. Unexpectedly, we find a significant reduction of the lattice thermal conductivity at room temperature as the carrier concentration goes above 10(19) cm(-3) (the reduction reaches up to 45% in p-type silicon at around 10(21) cm(-3)), a range of great technological relevance to thermoelectric materials.
Scientific Reports | 2015
Lingping Zeng; Kimberlee C. Collins; Yongjie Hu; Maria N. Luckyanova; Alexei Maznev; Samuel Huberman; Vazrik Chiloyan; Jiawei Zhou; Xiaopeng Huang; Keith A. Nelson; Gang Chen
Heat conduction in semiconductors and dielectrics depends upon their phonon mean free paths that describe the average travelling distance between two consecutive phonon scattering events. Nondiffusive phonon transport is being exploited to extract phonon mean free path distributions. Here, we describe an implementation of a nanoscale thermal conductivity spectroscopy technique that allows for the study of mean free path distributions in optically absorbing materials with relatively simple fabrication and a straightforward analysis scheme. We pattern 1D metallic grating of various line widths but fixed gap size on sample surfaces. The metal lines serve as both heaters and thermometers in time-domain thermoreflectance measurements and simultaneously act as wire-grid polarizers that protect the underlying substrate from direct optical excitation and heating. We demonstrate the viability of this technique by studying length-dependent thermal conductivities of silicon at various temperatures. The thermal conductivities measured with different metal line widths are analyzed using suppression functions calculated from the Boltzmann transport equation to extract the phonon mean free path distributions with no calibration required. This table-top ultrafast thermal transport spectroscopy technique enables the study of mean free path spectra in a wide range of technologically important materials.
Applied Physics Letters | 2016
Lingping Zeng; Vazrik Chiloyan; Samuel Huberman; A. A. Maznev; Jean-Philippe M. Péraud; Nicolas G. Hadjiconstantinou; Keith A. Nelson; Gang Chen
The impact of boundary scattering on non-diffusive thermal relaxation of a transient grating in thin membranes is rigorously analyzed using the multidimensional phonon Boltzmann equation. The gray Boltzmann simulation results indicate that approximating models derived from previously reported one-dimensional relaxation model and Fuchs-Sondheimer model fail to describe the thermal relaxation of membranes with thickness comparable with phonon mean free path. Effective thermal conductivities from spectral Boltzmann simulations free of any fitting parameters are shown to agree reasonably well with experimental results. These findings are important for improving our fundamental understanding of non-diffusive thermal transport in membranes and other nanostructures.
Physical Review B | 2016
Vazrik Chiloyan; Lingping Zeng; Samuel Huberman; Alexei Maznev; Keith A. Nelson; Gang Chen
The phonon Boltzmann transport equation (BTE) is a powerful tool for studying nondiffusive thermal transport. Here, we develop a new universal variational approach to solving the BTE that enables extraction of phonon mean free path (MFP) distributions from experiments exploring nondiffusive transport. By utilizing the known Fourier heat conduction solution as a trial function, we present a direct approach to calculating the effective thermal conductivity from the BTE. We demonstrate this technique on the transient thermal grating experiment, which is a useful tool for studying nondiffusive thermal transport and probing the MFP distribution of materials. We obtain a closed form expression for a suppression function that is materials dependent, successfully addressing the nonuniversality of the suppression function used in the past, while providing a general approach to studying thermal properties in the nondiffusive regime.
Proceedings of the National Academy of Sciences of the United States of America | 2015
Jiawei Zhou; Bolin Liao; Bo Qiu; Samuel Huberman; Keivan Esfarjani; Mildred S. Dresselhaus; Gang Chen
Significance It has been well known that the phonon drag effect—an extra electrical current induced by phonon heat flow via electron–phonon interaction—can lead to unusually high Seebeck coefficient at low temperatures. However, its use for improving thermoelectric performance has been controversial. Here, using first principles calculations we examine the phonon drag with detailed mode-specific contributions and reveal that even in heavily doped silicon at room temperature, phonon drag can still be significant, which challenges the previous belief that phonon drag vanishes in heavily doped samples. A phonon filter is designed to spectrally decouple the phonon drag from the heat conduction. Our simulation explores the coupled electron phonon transport and uncovers the possibility of optimizing the phonon drag for better thermoelectrics. Although the thermoelectric figure of merit zT above 300 K has seen significant improvement recently, the progress at lower temperatures has been slow, mainly limited by the relatively low Seebeck coefficient and high thermal conductivity. Here we report, for the first time to our knowledge, success in first-principles computation of the phonon drag effect—a coupling phenomenon between electrons and nonequilibrium phonons—in heavily doped region and its optimization to enhance the Seebeck coefficient while reducing the phonon thermal conductivity by nanostructuring. Our simulation quantitatively identifies the major phonons contributing to the phonon drag, which are spectrally distinct from those carrying heat, and further reveals that although the phonon drag is reduced in heavily doped samples, a significant contribution to Seebeck coefficient still exists. An ideal phonon filter is proposed to enhance zT of silicon at room temperature by a factor of 20 to ∼0.25, and the enhancement can reach 70 times at 100 K. This work opens up a new venue toward better thermoelectrics by harnessing nonequilibrium phonons.
Applied Physics Letters | 2018
Fei Tian; Bai Song; Bing Lv; Jingying Sun; Shuyuan Huyan; Qi Wu; Jun Mao; Yizhou Ni; Zhiwei Ding; Samuel Huberman; Te-Huan Liu; Gang Chen; Shuo Chen; C. W. Chu; Zhifeng Ren
Materials with high thermal conductivities are crucial to effectively cooling high-power-density electronic and optoelectronic devices. Recently, zinc-blende boron arsenide (BAs) has been predicted to have a very high thermal conductivity of over 2000 W m−1 K−1 at room temperature by first-principles calculations, rendering it a close competitor for diamond which holds the highest thermal conductivity among bulk materials. Experimental demonstration, however, has proved extremely challenging, especially in the preparation of large high quality single crystals. Although BAs crystals have been previously grown by chemical vapor transport (CVT), the growth process relies on spontaneous nucleation and results in small crystals with multiple grains and various defects. Here, we report a controllable CVT synthesis of large single BAs crystals (400–600 μm) by using carefully selected tiny BAs single crystals as seeds. We have obtained BAs single crystals with a thermal conductivity of 351 ± 21 W m−1 K−1 at room ...
Journal of Applied Physics | 2016
Vazrik Chiloyan; Lingping Zeng; Samuel Huberman; Alexei Maznev; Keith A. Nelson; Gang Chen
The phonon Boltzmann transport equation (BTE) is widely utilized to study non-diffusive thermal transport. We find a solution of the BTE in the thin film transient thermal grating (TTG) experimental geometry by using a recently developed variational approach with a trial solution supplied by the Fourier heat conduction equation. We obtain an analytical expression for the thermal decay rate that shows excellent agreement with Monte Carlo simulations. We also obtain a closed form expression for the effective thermal conductivity that demonstrates the full material property and heat transfer geometry dependence, and recovers the limits of the one-dimensional TTG expression for very thick films and the Fuchs-Sondheimer expression for very large grating spacings. The results demonstrate the utility of the variational technique for analyzing non-diffusive phonon-mediated heat transport for nanostructures in multi-dimensional transport geometries, and will assist the probing of the mean free path distribution of...
Physical Review Materials | 2017
Samuel Huberman; Vazrik Chiloyan; R. A. Duncan; Lingping Zeng; Roger Jia; Alexei Maznev; Eugene A. Fitzgerald; Keith A. Nelson; Gang Chen
In this work, we demonstrate the correspondence between first principle calculations and experimental measurements of size effects on thermal transport in SiGe alloys. Transient thermal grating (TTG) is used to measure the effective thermal conductivity. The virtual crystal approximation under the density functional theory (DFT) framework combined with impurity scattering is used to determine the phonon properties for the exact alloy composition of the measured samples. With these properties, classical size effects are calculated for the experimental geometry of reflection mode TTG using the recently-developed variational solution to the phonon Boltzmann transport equation (BTE), which is verified against established Monte Carlo simulations. We find agreement between theoretical predictions and experimental measurements in the reduction of thermal conductivity (as much as
Science Advances | 2018
Yanfei Xu; Xiaoxue Wang; Jiawei Zhou; Bai Song; Zhang Jiang; Elizabeth M. Y. Lee; Samuel Huberman; Karen K. Gleason; Gang Chen
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arXiv: Quantum Physics | 2015
Seth Lloyd; Zi-Wen Liu; Stefano Pirandola; Vazrik Chiloyan; Yongjie Hu; Samuel Huberman; Gang Chen
25\% of the bulk value) across grating periods spanning one order of magnitude. This work provides a framework for the tabletop study of size effects on thermal transport.