Metzke Christoph, Kühnel Fabian, Weber Jonas, Benstetter Günther
Department of Electrical Engineering and Media Technology, Deggendorf Institute of Technology, Dieter-Görlitz-Platz 1, 94469 Deggendorf, Germany.
Department of Electrical Engineering, Helmut Schmidt University/University of the Federal Armed Forces Hamburg, Holstenhofweg 85, 22043 Hamburg, Germany.
Nanomaterials (Basel). 2021 Feb 16;11(2):491. doi: 10.3390/nano11020491.
New micro- and nanoscale devices require electrically isolating materials with specific thermal properties. One option to characterize these thermal properties is the atomic force microscopy (AFM)-based scanning thermal microscopy (SThM) technique. It enables qualitative mapping of local thermal conductivities of ultrathin films. To fully understand and correctly interpret the results of practical SThM measurements, it is essential to have detailed knowledge about the heat transfer process between the probe and the sample. However, little can be found in the literature so far. Therefore, this work focuses on theoretical SThM studies of ultrathin films with anisotropic thermal properties such as hexagonal boron nitride (h-BN) and compares the results with a bulk silicon (Si) sample. Energy fluxes from the probe to the sample between 0.6 µW and 126.8 µW are found for different cases with a tip radius of approximately 300 nm. A present thermal interface resistance (TIR) between bulk Si and ultrathin h-BN on top can fully suppress a further heat penetration. The time until heat propagation within the sample is stationary is found to be below 1 µs, which may justify higher tip velocities in practical SThM investigations of up to 20 µms. It is also demonstrated that there is almost no influence of convection and radiation, whereas a possible TIR between probe and sample must be considered.
新型微纳尺度器件需要具有特定热性能的电绝缘材料。表征这些热性能的一种方法是基于原子力显微镜（AFM）的扫描热显微镜（SThM）技术。它能够对超薄膜的局部热导率进行定性映射。为了全面理解并正确解释实际SThM测量的结果，深入了解探针与样品之间的热传递过程至关重要。然而，目前在文献中几乎找不到相关内容。因此，这项工作聚焦于对具有各向异性热性能的超薄膜（如六方氮化硼（h-BN））进行SThM理论研究，并将结果与块状硅（Si）样品进行比较。对于尖端半径约为300 nm的不同情况，可以发现从探针到样品的能量通量在0.6 μW至126.8 μW之间。块状硅与顶部超薄膜h-BN之间目前的热界面电阻（TIR）能够完全抑制进一步的热渗透。发现样品内热传播达到稳定状态所需的时间低于1 μs，这可能为实际SThM研究中高达20 μm/s的更高尖端速度提供了依据。研究还表明，对流和辐射几乎没有影响，而必须考虑探针与样品之间可能存在的TIR。
