Precise Thermal Characterization of Confined Nanocrystalline Silicon by a $3\omega$ Method

概要

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Due to a strong quantum confinement effect, the thermal conductivity and heat capacity per unit volume of a nanocrystalline silicon (nc-Si) layer prepared by electrochemical anodization are extremely lowered in comparison to those of single crystal silicon (c-Si). Based on this high contrast between the thermal properties of nc-Si and c-Si, we have developed novel thermally induced ultrasound emitter devices. The thermal insulating properties of the nc-Si layer play a key role in this case. This paper concerns precise measurements of the thermal conductivity and heat capacity per unit volume of the nc-Si layer using a dynamic approach called the $3\omega$ method. The measured thermal conductivity is $1.08\pm 0.2$ W/(m$\cdot$K) in good agreement with that reported previously as measured by conventional techniques. The obtained heat capacity per unit volume of the nc-Si layer is, on the other hand, considerably smaller than that estimated from the porosity of the sample. These results provide useful information for designing an efficient ultrasound emitter.
Published by the Japan Society of Applied Physics through the Institute of Pure and Applied Physicsの論文
2005-06-15