The synthesis of transfer-free graphene at metal–substrate interfaces using a sacrificial metal film deposited on dielectric substrates is promising for producing graphene for industrial applications. However, although no complex transfer process is used in the aforementioned method, an etching process is required to remove the overlying sacrificial metal to expose the interfacial transfer-free graphene. The conventional etching method, which involves immersing metal-covered, transfer-free graphene into an etchant solution for metal removal, has been extensively applied while it is highly dependent on individual handling skills. Thus, this method does not provide suitable reproducibility and scalability. In this study, we designed a laminar flow-assisted etching method by using a microfluidic system to remove the metal film on graphene in a well-controlled and smooth manner. The coverage of transfer-free graphene retained on a silica substrate after using the designed etching method (95%) was considerably higher than that of transfer-free graphene produced by the conventional etching process (64%). The produced graphene contained uniform monolayers with few defects and decent field-effect mobility of 1665 cm² V^–1 s^–1. In addition, this microfluidic etching method is highly compatible with automatic operation and thus provides advantages such as labor economization as well as high reproducibility, throughput, and scalability.

中文翻译：

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用于制备高质量无转移石墨烯的层流辅助金属蚀刻

使用沉积在介电基板上的牺牲金属膜在金属 - 基板界面合成无转移石墨烯有望用于生产用于工业应用的石墨烯。然而，虽然在上述方法中没有使用复杂的转移工艺，但需要通过蚀刻工艺去除覆盖的牺牲金属以暴露出无界面转移的石墨烯。传统的蚀刻方法，包括将金属覆盖的、无转移的石墨烯浸入蚀刻剂溶液中进行金属去除，已被广泛应用，但它高度依赖于个人处理技能。因此，该方法不提供合适的再现性和可扩展性。在这项研究中，我们设计了一种层流辅助蚀刻方法，使用微流体系统以可控且平滑的方式去除石墨烯上的金属膜。使用设计的蚀刻方法后保留在二氧化硅基板上的无转移石墨烯的覆盖率（95%）大大高于传统蚀刻工艺生产的无转移石墨烯的覆盖率（64%）。所生产的石墨烯含有均匀的单层，几乎没有缺陷，场效应迁移率达到 1665 cm² V ^–1秒^–1。此外，这种微流控蚀刻方法与自动化操作高度兼容，因此具有节省劳动力以及高再现性、吞吐量和可扩展性等优点。