Ultrathin calcium fluoride insulators for two-dimensional field-effect transistors
Ultrathin calcium fluoride insulators for two-dimensional field-effect transistors
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DOI：
10.1038/s41928-019-0256-8
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发表时间：
2019-06-01
影响因子：
34.3
通讯作者：
Grasser, Tibor
中科院分区：
文献类型：
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作者：
Illarionov, Yury Yu;Banshchikov, Alexander G.;Grasser, Tibor
二维半导体可以用来制造最终规模的场效应晶体管和超过摩尔的纳米电子器件。然而，如果没有合适的可扩展到纳米范围的栅极绝缘体，这些目标就无法实现。然而，通常使用的氧化物（例如SiO2、Al 2 O3和HfO 2）在缩放时是非晶的，并且2D六方氮化硼表现出过量的栅极漏电流。在这里，我们表明，外延氟化钙（CaF 2），它可以形成一个准货车的德瓦尔斯接口与二维半导体，可以作为一个二维器件的半导体栅绝缘体。我们制造可扩展的双层MoS 2场效应晶体管与晶体CaF 2绝缘体的类似2 nm的厚度，这对应于小于1 nm的等效氧化物厚度。我们的器件具有低漏电流和具有竞争力的器件性能特性，包括低至90 mV dec（-1）的亚阈值摆幅、高达10（7）的开/关电流比和小迟滞。
Two-dimensional semiconductors could be used to fabricate ultimately scaled field-effect transistors and more-than-Moore nanoelectronic devices. However, these targets cannot be reached without appropriate gate insulators that are scalable to the nanometre range. Typically used oxides such as SiO2, Al2O3 and HfO2 are, however, amorphous when scaled, and 2D hexagonal boron nitride exhibits excessive gate leakage currents. Here, we show that epitaxial calcium fluoride (CaF2), which can form a quasi van der Waals interface with 2D semiconductors, can serve as an ultrathin gate insulator for 2D devices. We fabricate scalable bilayer MoS2 field-effect transistors with a crystalline CaF2 insulator of similar to 2 nm thickness, which corresponds to an equivalent oxide thickness of less than 1 nm. Our devices exhibit low leakage currents and competitive device performance characteristics, including subthreshold swings down to 90 mV dec(-1), on/off current ratios up to 10(7) and a small hysteresis.