In the growing area of neuromorphic and in-memory computing, there are multiple reviews available. Most of them cover a broad range of topics, which naturally comes at the cost of details in specific areas. Here, we address the specific area of multi-level resistive switching in hafnium-oxide-based devices for neuromorphic applications and summarize the progress of the most recent years. While the general approach of resistive switching based on hafnium oxide thin films has been very busy over the last decade or so, the development of hafnium oxide with a continuous range of programmable states per device is still at a very early stage and demonstrations are mostly at the level of individual devices with limited data provided. On the other hand, it is positive that there are a few demonstrations of full network implementations. We summarize the general status of the field, point out open questions, and provide recommendations for future work.

中文翻译：

---

用于神经形态计算的氧化铪基器件中的多级电阻开关

在不断发展的神经形态和内存计算领域，有多种评论可用。其中大多数涵盖广泛的主题，这自然是以牺牲特定领域的细节为代价的。在这里，我们讨论了用于神经形态应用的氧化铪基器件中多级电阻开关的特定领域，并总结了近年来的进展。虽然基于氧化铪薄膜的电阻开关的一般方法在过去十年左右一直非常繁忙，但每个器件具有连续范围的可编程状态的氧化铪的开发仍处于非常早期的阶段，并且演示大多在提供有限数据的单个设备的级别。另一方面，有一些完整网络实施的演示是积极的。我们总结了该领域的总体状况，指出了悬而未决的问题，并为未来的工作提供了建议。