High tunnelling electroresistance in a ferroelectric van der Waals heterojunction via giant barrier height modulation
High tunnelling electroresistance in a ferroelectric van der Waals heterojunction via giant barrier height modulation
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DOI：
10.1038/s41928-020-0441-9
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发表时间：
2020-07-06
影响因子：
34.3
通讯作者：
Wang, Han
中科院分区：
文献类型：
--
作者：
Wu, Jiangbin;Chen, Hung-Yu;Wang, Han
铁电隧道结使用薄铁电层作为隧道势垒，其高度可以通过切换其铁电极化来修改。该结具有低功耗、非易失性开关和非破坏性读出等优点，在存储器和计算领域具有广阔的应用前景。然而，在这些器件中实现高隧穿电阻（TER）仍然具有挑战性。典型的结，例如基于钛酸钡或二氧化铪的结，受到其约0.1 eV的小势垒高度调制的限制。在这里，我们报告了一种铁电隧道结，使用层状铜铟硫代磷酸盐（CuInP2S6）作为铁电势垒，石墨烯和铬作为非对称接触。CuInP（2）S（6）中的铁电场效应可以在结中引起1eV的势垒高度调制，导致TER大于10（7）。利用Kelvin探针力显微镜和拉曼光谱分析表明，这种调制是由于半金属石墨烯在狄拉克点附近的低态密度和小的量子电容引起的。采用铜铟硫代磷酸盐作为铁电势垒，石墨烯和铬作为非对称接触的铁电隧道结可以在开态和关态之间提供高的电阻比。
Ferroelectric tunnel junctions use a thin ferroelectric layer as a tunnelling barrier, the height of which can be modified by switching its ferroelectric polarization. The junctions can offer low power consumption, non-volatile switching and non-destructive readout, and thus are promising for the development of memory and computing applications. However, achieving a high tunnelling electroresistance (TER) in these devices remains challenging. Typical junctions, such as those based on barium titanate or hafnium dioxide, are limited by their small barrier height modulation of around 0.1 eV. Here, we report a ferroelectric tunnel junction that uses layered copper indium thiophosphate (CuInP2S6) as the ferroelectric barrier, and graphene and chromium as asymmetric contacts. The ferroelectric field effect in CuInP(2)S(6)can induce a barrier height modulation of 1 eV in the junction, which results in a TER of above 10(7). This modulation, which is shown using Kelvin probe force microscopy and Raman spectroscopy, is due to the low density of states and small quantum capacitance near the Dirac point of the semi-metallic graphene.A ferroelectric tunnel junction that uses copper indium thiophosphate as the ferroelectric barrier, and graphene and chromium as asymmetric contacts, can offer a high resistance ratio between on and off states.