Black phosphorus (bP) is the second known elemental allotrope with a layered crystal structure that can be mechanically exfoliated to atomic layer thickness. Unlike metallic graphite and semi-metallic graphene, bP is a semiconductor in both bulk and few-layer form. Here we fabricate bP-naked quantum wells in a back-gated field effect transistor geometry with bP thicknesses ranging from 6±1 nm to 47±1 nm. Using a polymer encapsulant, we suppress bP oxidation and observe field effect mobilities up to 900 cm(2) V(-1) s(-1) and on/off current ratios exceeding 10(5). Shubnikov-de Haas oscillations observed in magnetic fields up to 35 T reveal a 2D hole gas with Schrödinger fermion character in a surface accumulation layer. Our work demonstrates that 2D electronic structure and 2D atomic structure are independent. 2D carrier confinement can be achieved without approaching atomic layer thickness, advantageous for materials that become increasingly reactive in the few-layer limit such as bP.

中文翻译：

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黑磷裸量子阱中的二维磁传输。

黑磷（bP）是第二种已知的元素同素异形体，具有可机械剥落至原子层厚度的层状晶体结构。与金属石墨和半金属石墨烯不同，bP是块状和多层结构的半导体。在这里，我们以背栅场效应晶体管的几何形状制造bP裸量子阱，其bP厚度范围为6±1 nm至47±1 nm。使用聚合物密封剂，我们抑制了bP氧化，并观察了高达900 cm（2）V（-1）s（-1）的场效应迁移率和开/关电流比超过10（5）。在高达35 T的磁场中观察到的Shubnikov-de Haas振荡揭示了在表面堆积层中具有Schrödinger费米子特征的二维空穴气体。我们的工作表明2D电子结构和2D原子结构是独立的。