Abstract
We demonstrate an experimental method to obtain information of thermal phonon mean free path (MFP) spectra in thin films using hole based two dimensional phononic crystal nanostructures. The characteristic length of the system can be swept by changing the radius of circular holes of the phononic crystals. Then, thermal conductivities of single-crystalline Si, amorphous SiGe, and poly-SiGe thin films (150 nm thick) were measured for phononic crystals with different characteristic length between 20 nm and 200 nm. We observed different characteristic length dependence of the thermal conductivity among these three systems and the trend can be explained by the thermal phonon MFP spectra of the materials.
Highlights
Nanoscale heat transfer has been investigated because of its importance in both fundamental physics and other applications, such as thermoelectrics.1 The thermal phonon mean free path (MFP) is an important physical parameter and determines the thermophysical property of a system
For SiGe samples, an amorphous Si0.5Ge0.5 layer with a thickness of 150 nm was deposited on the SiO2/Si(001) substrate using solidsource molecular-beam-epitaxy at room temperature
Most of the thermal phonon in Si at room temperature have MFPs between 100 nm and 10 m, resulting in Si showing a high sensitivity to phononic crystal (PnC) nanostructures with a characteristic size of around 100 nm
Summary
M Nomura, J Nakagawa, K Sawano, J Maire, Sebastian Volz. Probing thermal phonon mean free path using phononic crystal nanostructures. Journal of Physics: Conference Series, IOP Publishing, 2018, 1052, 10.1088/1742-6596/1052/1/012123. HAL is a multi-disciplinary open access archive for the deposit and dissemination of scientific research documents, whether they are published or not. The documents may come from teaching and research institutions in France or abroad, or from public or private research centers. L’archive ouverte pluridisciplinaire HAL, est destinée au dépôt et à la diffusion de documents scientifiques de niveau recherche, publiés ou non, émanant des établissements d’enseignement et de recherche français ou étrangers, des laboratoires publics ou privés. View the article online for updates and enhancements
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