Hoque Md Shafkat Bin, Koh Yee Rui, Braun Jeffrey L, Mamun Abdullah, Liu Zeyu, Huynh Kenny, Liao Michael E, Hussain Kamal, Cheng Zhe, Hoglund Eric R, Olson David H, Tomko John A, Aryana Kiumars, Galib Roisul, Gaskins John T, Elahi Mirza Mohammad Mahbube, Leseman Zayd C, Howe James M, Luo Tengfei, Graham Samuel, Goorsky Mark S, Khan Asif, Hopkins Patrick E
Department of Mechanical and Aerospace Engineering, University of Virginia, Charlottesville, Virginia 22904, United States.
Department of Electrical Engineering, University of South Carolina, Columbia, South Carolina 29208, United States.
ACS Nano. 2021 Jun 22;15(6):9588-9599. doi: 10.1021/acsnano.0c09915. Epub 2021 Apr 28.
High thermal conductivity materials show promise for thermal mitigation and heat removal in devices. However, shrinking the length scales of these materials often leads to significant reductions in thermal conductivities, thus invalidating their applicability to functional devices. In this work, we report on high in-plane thermal conductivities of 3.05, 3.75, and 6 μm thick aluminum nitride (AlN) films measured steady-state thermoreflectance. At room temperature, the AlN films possess an in-plane thermal conductivity of ∼260 ± 40 W m K, one of the highest reported to date for any thin film material of equivalent thickness. At low temperatures, the in-plane thermal conductivities of the AlN films surpass even those of diamond thin films. Phonon-phonon scattering drives the in-plane thermal transport of these AlN thin films, leading to an increase in thermal conductivity as temperature decreases. This is opposite of what is observed in traditional high thermal conductivity thin films, where boundaries and defects that arise from film growth cause a thermal conductivity reduction with decreasing temperature. This study provides insight into the interplay among boundary, defect, and phonon-phonon scattering that drives the high in-plane thermal conductivity of the AlN thin films and demonstrates that these AlN films are promising materials for heat spreaders in electronic devices.
高导热率材料在器件的热缓解和散热方面显示出应用前景。然而，缩小这些材料的尺寸往往会导致其热导率显著降低，从而使其无法应用于功能性器件。在这项工作中，我们报告了通过稳态热反射测量得到的3.05、3.75和6μm厚的氮化铝（AlN）薄膜具有高的面内热导率。在室温下，AlN薄膜的面内热导率约为260±40W m⁻¹ K⁻¹，是迄今报道的同等厚度的任何薄膜材料中最高的之一。在低温下，AlN薄膜的面内热导率甚至超过了金刚石薄膜。声子 - 声子散射驱动了这些AlN薄膜的面内热传输，导致热导率随温度降低而增加。这与传统高导热率薄膜中观察到的情况相反，在传统薄膜中，由薄膜生长产生的边界和缺陷会导致热导率随温度降低而减小。这项研究深入了解了驱动AlN薄膜高面内热导率的边界、缺陷和声子 - 声子散射之间的相互作用，并表明这些AlN薄膜是电子器件中热扩散器的有前途的材料。
