School of Electrical and Electronics Engineering, Nanyang Technological University, Block S1, 50 Nanyang Avenue, Singapore 639798.
Nanoscale. 2015 Dec 7;7(45):18984-91. doi: 10.1039/c5nr05009j. Epub 2015 Oct 29.
Vertically self-ordered hexagonal boron nitride (ordered h-BN) is a highly ordered turbostratic BN (t-BN) material similar to hexagonal BN, with its planar structure perpendicularly oriented to the substrate. The ordered h-BN thin films were grown using a High Power Impulse Magnetron Sputtering (HiPIMS) system with a lanthanum hexaboride (LaB6) target reactively sputtered in nitrogen gas. The best vertical alignment was obtained at room temperature, with a grounded bias and a HiPIMS peak power density of 60 W cm(-2). Even though the film contains up to 7.5 at% lanthanum, it retains its highly insulative properties and it was observed that an increase in compressive stress is correlated to an increase in film ordering quality. Importantly, the thermal conductivity of vertically ordered h-BN is considerably high at 5.1 W m(-1) K(-1). The favourable thermal conductivity coupled with the dielectric properties of this novel material and the low temperature growth could outperform SiO2 in high power density electronic applications.
垂直有序六方氮化硼（有序 h-BN）是一种高度有序的类六方 BN（t-BN）材料，其平面结构垂直于衬底。采用高功率脉冲磁控溅射（HiPIMS）系统，以镧六硼化物（LaB6）为靶材，在氮气中反应溅射，生长出有序 h-BN 薄膜。在室温下，采用接地偏压和 60 W cm(-2) 的 HiPIMS 峰值功率密度，可获得最佳的垂直取向。尽管薄膜中含有高达 7.5 at%的镧，但它仍保持着高度的绝缘性能，并且观察到压缩应力的增加与薄膜有序度的提高相关。重要的是，垂直有序 h-BN 的热导率相当高，达到 5.1 W m(-1) K(-1)。这种新型材料的热导率、介电性能以及低温生长条件都非常有利，有望在高功率密度电子应用中超过 SiO2。
