Two-dimensional transition metal carbides are promising materials because of their potential for combining the favorable properties of transition metal carbides with the high aspect ratio of two-dimensional materials. Though commonly produced by top-down wet-chemical synthesis methods, synthesis by chemical vapor deposition is being considered because of its ability to achieve large areas, controlled layer thickness, and reduced defect density. Typically, liquid Cu is used as a synthesis substrate, though the high melting temperature of Cu (1085 °C) requires high synthesis temperatures. Thus, alternative substrates have been studied in order to reduce the necessary melting temperature. This work systematically studies the impact of synthesis parameters and substrate composition on the growth of ultrathin Mo₂C (∼4–120 nm thick) by chemical vapor deposition on an In-Cu alloy. Mo₂C flake size increases, and graphene/Mo₂C heterostructures form with an increase in the methane flow rates. Increasing the In composition slightly decreases surface coverage and coalescence but does not appreciably impact the Mo₂C flake size. Increasing In content also decreases the alloy substrate melting temperature so that a lower temperature synthesis (800 °C) can be performed. However, the necessary high temperatures for pyrolysis of methane lead to a lower limit for the synthesis temperature, similar to graphene.

中文翻译：

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In-Cu合金衬底，用于Mo2C的低温化学气相沉积

二维过渡金属碳化物是有前途的材料，因为它们具有将过渡金属碳化物的良好特性与二维材料的高长宽比相结合的潜力。尽管通常通过自上而下的湿化学合成方法生产，但是由于其能够实现大面积，可控的层厚度和降低的缺陷密度，因此正在考虑通过化学气相沉积进行合成。尽管Cu的高熔化温度（1085°C）需要较高的合成温度，但通常将液态Cu用作合成基质。因此，已经研究了可替代的基材以降低必要的熔融温度。这项工作系统地研究了合成参数和底物组成对超薄Mo ₂生长的影响。通过在In-Cu合金上进行化学气相沉积获得C（约4-120 nm厚）。Mo ₂ C薄片的尺寸增加，并且随着甲烷流速的增加，形成石墨烯/ Mo ₂ C异质结构。In成分的增加会稍微降低表面覆盖率和聚结，但不会明显影响Mo ₂ C薄片的尺寸。In含量的增加还降低了合金基材的熔融温度，从而可以进行较低温度的合成（800℃）。然而，类似于石墨烯，甲烷热解所需的高温导致合成温度的下限。