Grain boundary engineering of 2D materials for nano-ionic Resistive Switches

电阻开关（rram）是未来非易失性存储器和逻辑存储器架构的有希望的候选者。在这些双端器件中，通过对短电压脉冲的器件电阻进行可逆操作来编码逻辑状态。电阻转变归因于纳米级导电丝的生长和断裂，这是由移动氧空位或金属阳离子（如银或铜离子）的迁移驱动的，具体取决于所使用的材料。在后一种情况下，预计开关能量将低于10 fJ/bit。尽管它们的优点包括可扩展性和与节省成本的标准后端制造工艺的兼容性，但由于不受控制的金属颗粒扩散而导致的较差的器件稳定性阻碍了它们的实际应用。石墨烯最近被认为是超薄的二维扩散屏障。然而，离子在集成在rram中的二维材料中的扩散尚未被探索，这阻碍了器件的优化。我们提出在垂直和横向电阻开关中集成二维六方氮化硼（hBN）。特别是，我们将描述晶界存在时的开关行为，并分析如何利用和调整晶界来提高开关性能。电测量将由最近引进的一种技术补充，即所谓的等离子体增强光谱学，以探测电阻开关时的形态变化。由于开关过程中环境大气的影响很大，因此将利用原位环境显微镜和光谱技术进一步分析开关机制。该项目将使人们对这些设备的理解发生重大变化，这是释放其全部应用潜力所必需的。

Resistive switches (RRAMs) are promising candidates for future non-volatile memories and logic-in-memory architectures. In these two-terminal devices, logic states are encoded by reversible manipulation of the device resistance upon short voltage pulses. The resistance transition is attributed to the growth and rupture of a nanoscale conductive filament driven by the migration of mobile oxygen vacancies or metal cations, such as silver or copper ions depending on the materials used. In the latter case ultra-low switching energies below 10 fJ/bit are predicted. Despite their advantages including, scalability and compatibility with cost-saving standard back-end-of-line fabrication processes, the inferior device stability due to uncontrolled metal particle diffusion impedes their practical application. Graphene has been recently suggested as ultra-thin two-dimensional diffusion barrier. However, the ion diffusion through 2D materials integrated in RRAMs is unexplored which hinders device optimisation. We propose to integrated two-dimensional hexagonal boron nitride (hBN) in vertical and lateral resistive switches. In particular, we will characterize the switching behaviour in presence of grain boundaries and analyze how these can be exploited and tuned to improve the switching performance. Electrical measurements will be complemented by a recently introduced technique, so called plasmon-enhanced spectroscopy, to probe morphological changes upon resistive switching. As the ambient atmosphere is significantly involved during the switching, switching mechanisms will be further analyzed using in situ environmental microscopic and spectroscopic techniques. This project will bring a step change in the understanding of these devices, which is needed to unlock their full application potential.