Complementary metal–oxide–semiconductor (CMOS) logic circuits at their ultimate scaling limits place extreme demands on the properties of all materials involved. The requirements for semiconductors are well explored and could possibly be satisfied by a number of layered two-dimensional (2D) materials, such as transition metal dichalcogenides or black phosphorus. The requirements for gate insulators are arguably even more challenging. At present, hexagonal boron nitride (hBN) is the most common 2D insulator and is widely considered to be the most promising gate insulator in 2D material-based transistors. Here we assess the material parameters and performance limits of hBN. We compare experimental and theoretical tunnel currents through ultrathin layers (equivalent oxide thickness of less than 1 nm) of hBN and other 2D gate insulators, including the ideal case of defect-free hBN. Though its properties make hBN a candidate for many applications in 2D nanoelectronics, excessive leakage currents lead us to conclude that hBN is unlikely to be suitable for use as a gate insulator in ultrascaled CMOS devices.

互补金属氧化物半导体（CMOS）逻辑电路在其极限尺寸极限下，对所有相关材料的性能提出了极高的要求。半导体的要求已得到很好的探索，并可能通过许多层状二维（2D）材料来满足，例如过渡金属二卤化物或黑磷。栅极绝缘子的要求无疑更具挑战性。目前，六方氮化硼（hBN）是最常见的2D绝缘体，并被广泛认为是2D基于材料的晶体管中最有希望的栅极绝缘体。在这里，我们评估hBN的材料参数和性能极限。我们比较了通过hBN和其他2D栅极绝缘体的超薄层（等效氧化物厚度小于1 nm）的实验和理论隧道电流，包括无缺陷hBN的理想情况。尽管hBN的特性使其成为2D纳米电子学中许多应用的候选者，但过大的泄漏电流使我们得出结论，hBN不太适合用作超大规模CMOS器件的栅极绝缘体。