Unusually High and Anisotropic Thermal Conductivity in Amorphous Silicon Nanostructures
Autor: | Renkun Chen, Shuang Cui, Jianlin Zheng, Soonshin Kwon, Matthew C. Wingert |
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Rok vydání: | 2016 |
Předmět: |
Amorphous silicon
Range (particle radiation) Condensed Matter - Materials Science Nanostructure Materials science Condensed matter physics Mean free path General Engineering General Physics and Astronomy Materials Science (cond-mat.mtrl-sci) FOS: Physical sciences Nanotechnology 02 engineering and technology 021001 nanoscience & nanotechnology 01 natural sciences Amorphous solid chemistry.chemical_compound Thermal conductivity chemistry Molecular vibration 0103 physical sciences General Materials Science 010306 general physics 0210 nano-technology Anisotropy |
DOI: | 10.48550/arxiv.1608.07633 |
Popis: | Amorphous Si (a-Si) nanostructures are ubiquitous in numerous electronic and optoelectronic devices. Amorphous materials are considered to possess the lower limit to the thermal conductivity (k), which is ~1 W/m-K for a-Si. However, recent work suggested that k of micro-thick a-Si films can be greater than 3 W/m-K, which is contributed by propagating vibrational modes, referred to as "propagons". However, precise determination of k in a-Si has been elusive. Here, we used novel structures of a-Si nanotubes and suspended a-Si films that enabled precise in-plane k measurement within a wide thickness range of 5 nm to 1.7 um. We showed unexpectedly high in plane k in a-Si nanostructures, reaching ~3.0 and 5.3 W/m-K at 100 nm and 1.7 um, respectively. Furthermore, the measured in plane k is significantly higher than the cross-plane k on the same films. This usually high and anisotropic k in the amorphous Si nanostructures manifests the surprising broad propaganda mean free path distribution, which is found to range from 10 nm to 10 um, in the disordered and atomically isotropic structure. This result provides an unambiguous answer to the century-old problem regarding the mean free path distribution of propagons and also shed light on the design and performance of numerous a-Si based electronic and optoelectronics devices. Comment: 5 figures |
Databáze: | OpenAIRE |
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