Single-layer high-quality hexagonal boron nitride single crystal domains prepared by Shanghai Microsystems
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The Chinese Academy of Sciences Shanghai Institute of Microsystems and Information Technology has made new progress in two-dimensional material research. Lu Guangyuan and Wu Tianru of the State Key Laboratory of Superconducting Laboratory and Information Functional Materials used chemical vapor deposition (CVD) to successfully prepare single-layer high-quality hexagonal boron nitride (h-BN) on copper-nickel alloy substrates. Single crystal domains, single crystal area is about 2 orders of magnitude higher than reported in the literature, the research paper Synthesis of large single-crystal hexagonal boron nitride grains on Cu-Ni alloy was published in Nature Communications on January 21st (6:6160 doi: 10.1038/ncomms7160 (2015)).
h-BN, commonly known as white graphite, has the same crystal structure as graphite and is highly anisotropic. It can be used to prepare monolayer h-BN by mechanical stripping. Because of the smooth surface, no suspension, good chemical stability, and good dielectric properties, h-BN can be used as a high-performance substrate for graphene, and can also form heterojunctions and superstructures with graphene. Device and device exploration has important potential for application and is an important hotspot in the field of two-dimensional material research. The CVD method is the main technical route for the large-scale production of h-BN. Commonly used catalysts are metals such as copper, nickel and platinum. Due to the high nucleation density, the previously reported size of h-BN single crystals is generally smaller (<50 μm2).
The team of Shanghai Institute of Microsystems found that by solid-dissolving a certain percentage of nickel in the copper substrate, the nucleation density of h-BN can be greatly reduced. By studying the stability of h-BN on the alloy substrate and optimizing the growth process parameters, A high-quality single-layer h-BN single crystal domain up to 7500 μm2 was successfully prepared, which is about two orders of magnitude higher than reported in the literature. The paper also verifies the effects of single-layer and multi-layer h-BN on shielding SiO2 substrate and improving the mobility of graphene carriers. The research progress lays an important experimental basis for the development of wafer-level h-BN, h-BN/graphene heterojunctions and superstructures. The excellent characteristics of h-BN are also expected to be used in the research of the noise mechanism of superconducting devices.
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