熱傳導與多種奈米線長度關係的量測

Abstract

近年來，出現了許多實驗技術，用來量測奈米尺度下的溫度。然而，目前還不能確定這些方法能否得到一致的結果，特別是因為接觸熱阻無法從總熱阻中分離出來。在本論文中，提出了一種實驗方法，利用掃描電子顯微鏡（SEM）來量測各奈米線在不同電子束照射位置的溫度與其熱傳輸性質，特別針對碳化矽（SiC）、鎳（Ni）和氮化矽（SiNx）奈米線。我用了兩種不同的分析方法得到一致的結果，確認這種方法的可行性。雖然沒有量測熱裝置的導熱性，但是透過這兩種分析方法，我們仍可以確定兩個熱裝置之間的熱導性差異，最大可高達 19.4%。此外，我們發現用電子束誘導沉積方法到接觸點可以改善接觸熱阻，最大可增強達 241%。實驗結果說明，所有的奈米線都表現出擴散傳輸 (至少平均自由徑少於 200 奈米)，最好的表面熱傳導為 56 MWm-2K-1，約等於由時域熱反射(TDTR)方法測得的銠/氧化鋁的表面熱傳導。

In recent times, numerous experimental techniques have emerged for measurements of temperatures at nanoscale levels. Nonetheless, it remains uncertain whether these methods would produce consistent results, especially when the contact thermal resistance cannot be separated from the total thermal resistance. In this study, we invented an experimental approach utilizing a scanning electron microscope (SEM) to determine the local temperature at different electron beam illumination position of nanowires and the thermal transport properties, particularly for silicon carbide (SiC), nickel (Ni), and silicon nitride (SiNx) nanowires. We obtained consistent results using two different analytical methods, confirming the feasibility of this approach. Due to the lack of thermal conductance measurements for the thermal devices, through these two analytical methods, we can still determine the thermal conductance difference between the two measurement devices, which can be as much as 19.4%. Furthermore, we found that applying the electron-beam-induced deposition method to the contact points can improve the contact thermal resistance, with a maximum enhancement of up to 241%. The results show that all nanowires exhibit diffusive transport (phonon mean free path should be less than 200 nm), and the best interfacial thermal conductance is 56 MWm-2K-1, which is approximately equivalent to interfacial thermal conductance of Rh/AL2O3 as measured by time-domain thermoreflectance (TDTR) method.