Onodera Momoko, Taniguchi Takashi, Watanabe Kenji, Isayama Miyako, Masubuchi Satoru, Moriya Rai, Machida Tomoki
Institute of Industrial Science , University of Tokyo , 4-6-1 Komaba , Meguro , Tokyo 153-8505 , Japan.
National Institute for Materials Science , 1-1 Namiki , Tsukuba 305-0044 , Japan.
Nano Lett. 2020 Jan 8;20(1):735-740. doi: 10.1021/acs.nanolett.9b04641. Epub 2019 Dec 26.
Hexagonal boron nitride (h-BN) synthesized under high pressure and high temperature (HPHT) has been used worldwide in two-dimensional (2D) materials research as an essential material for constructing van der Waals heterostructures. Here, we study h-BN synthesized with another method, i.e., via synthesis at pressure and high temperature (APHT) using a metal alloy solvent. First, we examine the APHT h-BN in a bulk crystal form using cathodoluminescence and find that it does not have carbon-rich domains that inevitably exist in a core region of all the HPHT h-BN crystals. Next, we statistically compare the size of the crystal flakes exfoliated on a SiO/Si substrate from APHT and HPHT h-BN crystals by employing our automated 2D material searching system. Finally, we provide direct evidence that APHT h-BN can serve as a high-quality substrate for 2D materials by demonstrating high carrier mobility, ballistic transport, and Hofstadter butterfly in graphene and photoluminescence in WS.
在高压高温（HPHT）条件下合成的六方氮化硼（h-BN）作为构建范德华异质结构的重要材料，已在全球二维（2D）材料研究中得到广泛应用。在此，我们研究了通过另一种方法合成的h-BN，即使用金属合金溶剂在常压高温（APHT）下合成。首先，我们利用阴极发光对块状晶体形式的APHT h-BN进行了研究，发现它没有在所有HPHT h-BN晶体核心区域不可避免存在的富碳区域。接下来，我们通过使用我们的自动化二维材料搜索系统，对从APHT和HPHT h-BN晶体在SiO/Si衬底上剥离的晶体薄片尺寸进行了统计比较。最后，我们通过展示石墨烯中的高载流子迁移率、弹道输运和霍夫施塔特蝴蝶效应以及WS中的光致发光，提供了直接证据，证明APHT h-BN可作为二维材料的高质量衬底。
