Engineering the thermal conductivity along an individual silicon nanowire by selective helium ion irradiation

Zhao, Yunshan; Liú, Dan; Chen, Jie; Zhu, Liyan; Belianinov, Alex; Ovchinnikova, Olga S.; Unocic, Raymond R.; Burch, Matthew J.; Kim, Songkil; Hao, Hanfang; Pickard, D. S.; Li, Baowen; Thong, John T. L.

doi:10.1038/ncomms15919

Cited by 70 publications

(56 citation statements)

References 55 publications

(70 reference statements)

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“…An electron‐beam technique was employed to measure the thermal conductivity of single nanowires . Briefly, we use the focused electron beam as a heating source and the two suspended islands with platinum loops act as resistance thermometers.…”

Section: Introductionmentioning

confidence: 99%

Ultralow Thermal Conductivity of Single‐Crystalline Porous Silicon Nanowires

Zhao

Yang

Kong

et al. 2017

Adv Funct Materials

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Porous materials provide a large surface-to-volume ratio, thereby providing a knob to alter fundamental properties in unprecedented ways. In thermal transport, porous nanomaterials can reduce thermal conductivity by not only enhancing phonon scattering from the boundaries of the pores and therefore decreasing the phonon mean free path, but also by reducing the phonon group velocity. Herein, a structure-property relationship is established by measuring the porosity and thermal conductivity of individual electrolessly etched single-crystalline silicon nanowires using a novel electron-beam heating technique. Such porous silicon nanowires exhibit extremely low diffusive thermal conductivity (as low as 0.33 W m −1 K −1 at 300 K for 43% porosity), even lower than that of amorphous silicon. The origin of such ultralow thermal conductivity is understood as a reduction in the phonon group velocity, experimentally verified by measuring the Young's modulus, as well as the smallest structural size ever reported in crystalline silicon (<5 nm). Molecular dynamics simulations support the observation of a drastic reduction in thermal conductivity of silicon nanowires as a function of porosity. Such porous materials provide an intriguing platform to tune phonon transport, which can be useful in the design of functional materials toward electronics and nanoelectromechanical systems.

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Section: Introductionmentioning

confidence: 99%

Ultralow Thermal Conductivity of Single‐Crystalline Porous Silicon Nanowires

Zhao

Yang

Kong

et al. 2017

Adv Funct Materials

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“…creation of amorphous segments along silicon nanowire. We had previously demonstrated the creation of an amorphous region of desired length along a single-crystal silicon nanowire by helium ion irradiation 27 . To obtain an amorphous silicon region with a much cleaner and sharper interface, we modified the irradiation conditions by calibrating the doses before irradiating the target nanowires, with details described in Supporting Information Fig.…”

Section: Resultsmentioning

confidence: 99%

Probing thermal transport across amorphous region embedded in a single crystalline silicon nanowire

Zhao

Liu

Rath

et al. 2020

Sci Rep

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While numerous studies have been carried out to characterize heat transport behaviours in various crystalline silicon nanostructures, the corresponding characteristics of amorphous one-dimension system have not been well understood. in this study, we amorphize crystalline silicon by means of helium-ion irradiation, enabling the formation of a completely amorphous region of well-defined length along a single silicon nanowire. Heat conduction across both amorphous region and its crystalline/amorphous interface is characterized by an electron beam heating technique with high measurement spatial resolution. the measured thermal conductivity of the amorphous silicon nanowire appears length-independence with length ranging from ~30 nm to few hundreds nm, revealing the fully diffusons governed heat conduction. Moreover, unlike the size-dependent interfacial thermal conductance at the interface between two one-dimensional crystalline materials, here for the first time, we observe that the interface thermal conductance across the amorphous/crystalline silicon interface is nearly independent of the length of the amorphous region. this unusual independence is further supported by molecular dynamics (MD) simulation in our work. Our results provide experimental and theoretical insight into the nature of interaction between heat carriers in crystalline and amorphous nano-structures and shed new light to design innovative silicon nanowire based devices. While crystalline materials are commonly studied, studying the thermal properties of non-crystalline materials, including all kinds of inorganic, organic, biological materials and their hybrid structures, is equally important, as it can significantly enrich our knowledge of energy transport in non-periodic lattices. Moreover, emergent technologies, like new generations of wearable electronics and soft machines, often exploit non-crystalline materials 1-3. In such materials, the phonon picture fails for atoms arranged in a disordered fashion, where heat is carried in a random channel among series of independent oscillators 4-6. This uncorrelated oscillator picture could be attributed to Einstein, who in 1911 7 predicted the low thermal conductivity limit for a completely amorphous disordered material, namely the "amorphous limit", in which the interactions between random oscillators lead to heat conduction. Since then, this amorphous limit model has been debated in numerous studies, since the values of thermal conductivity of amorphous solids reported were much higher. For amorphous silicon, a ubiquitous component of modern electronic devices, the thermal conductivity based on the calculated amorphous limit is below 2 W/m•K 8. Recent studies have shown that the thermal conductivity of amorphous silicon could be much higher 9,10 and as high as 4-5 W/m•K has been claimed 11. The fact of much higher thermal conductivity than the amorphous limit prediction for amorphous silicon has spurred numerous theoretical calculations to understand how heat carriers transport in amorphous silico...

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“…Semiconductor NWs have attracted considerable attention due to their potential applications in many areas, such as electronic devices [117,118], biosensors [119,120], thermoelectric devices [121][122][123][124] and optoelectronic devices [125][126][127][128]. The interest of investigating phonon transport in SiNWs has been greatly stimulated [129][130][131][132][133][134][135][136][137][138][139][140][141][142][143][144][145] since experiments [12,29] revealed that an approximately 100-fold reduction in thermal conductivity over bulk Si can be achieved in SiNWs, while the electrical conductivity and electron contribution to Seebeck coefficient are still similar to those of bulk silicon, which indicated that SiNWs could be applied as high-performance nanoscale thermoelectric materials. Further reducing thermal conductivity of SiNWs is critically important for achieving higher thermoelectric performance.…”

Section: Coherent Phonon Transport In Nwsmentioning

confidence: 99%

Phonon coherence and its effect on thermal conductivity of nanostructures

Xie

Ding

Zhang

2018

Advances in Physics: X

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The concept of coherence is one of the fundamental phenomena in electronics and optics. In addition to electron and photon, phonon is another important energy and information carrier in nature. Without any doubt, exploration of the phonon coherence and its impact on thermal conduction will markedly change many aspects in broad applications for heat control and management in the real world. So far, the application of coherent effect on manipulation of phonon transport is a challenging work. In this article, we review recent advances in the study of the phonon coherent transport in nanomaterials and nanostructures. We first briefly look back the classical and quantum theory of coherence. Next, we review the progresses made in the understanding of phonon coherence in superlattice, nanowires and nanomeshes, respectively, and focus on the effect of phonon coherence on thermal conductivity. Finally, we introduce the recent advances in the direct detection of phonon coherence using optical coherence theory. ARTICLE HISTORY

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Engineering the thermal conductivity along an individual silicon nanowire by selective helium ion irradiation

Cited by 70 publications

References 55 publications

Ultralow Thermal Conductivity of Single‐Crystalline Porous Silicon Nanowires

Ultralow Thermal Conductivity of Single‐Crystalline Porous Silicon Nanowires

Probing thermal transport across amorphous region embedded in a single crystalline silicon nanowire

Phonon coherence and its effect on thermal conductivity of nanostructures

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