The recently reported quasi-nonvolatile memory based on semi-floating gate architecture has attracted extensive attention thanks to its potential to bridge the large gap between volatile and nonvolatile memory. However, the further extension of the refresh time in quasi-nonvolatile memory is limited by the charge leakage through the p–n junction. Here, based on the density of states engineered van der Waals heterostructures, the leakage of electrons from the floating gate to the channel is greatly suppressed. As a result, the refresh time is effectively extended to more than 100 s, which is the longest among all previously reported quasi-nonvolatile memories. This work provides a new idea to enhance the refresh time of quasi-nonvolatile memory by the density of states engineering and demonstrates great application potential for high-speed and low-power memory technology.

光学薄膜元件的面形偏差会导致高精度激光系统中传输光束发生波前畸变，严重影响光学设备的性能。传统的面形偏差控制技术是采用双面镀膜，但需要反复抛光基片以获得高精度面形，这会大大增加研制成本，限制该方法的使用。文中基于离子束溅射沉积技术，采用薄膜应力形变模型预测镀膜后面形变化情况，然后对待镀元件的镀膜面预加工出与变形方向相反的面形，来补偿镀膜后膜层应力造成的薄膜元件变形，最后在预加工好的基片上制备超低面形的宽带高反膜，实现了在550~750 nm的工作波长下反射率R≥99.5%，面形PV≤0.15λ@632.8 nm。此项技术是通过标定薄膜材料的力学参数，预测在相同工艺条件下任意多层膜的面形变化，实现在超宽光谱设计的同时引入力学同步设计，制备出满足光、力双重指标的高质量光学薄膜。