A thin film cavity formed by stacking metal–insulator–metal (MIM) continuous layers is of significant interest as a lithography-free and scalable color-filtering structure. Such a cavity can selectively transmit a certain frequency range of incident light, thus producing vivid transmission colors. However, the generation of reflection colors with high purity and reflectivity is a challenge because a cavity in reflection mode resonantly absorbs a narrow range of wavelengths and reflects the remaining spectrum. This study shows that highly pure and reflective colors can be obtained by embedding an ultrathin Ge₂Sb₂Te₅ layer within the cavity. Because the MIM structure exhibits a nonuniform intensity distribution across the insulator layer, the approach is to place the Ge₂Sb₂Te₅ layer in a high-intensity region within the insulator and thereby create another absorption band in addition to the cavity resonance mode. When combined with the refractive-index engineering of the metal layer, this approach leads to red, green, and blue colors having a bandwidth of ∼100 nm and a reflection efficiency of 90%. The results of the study may be effectively utilized in numerous applications, including reflective color filters, colorimetric sensors, and surface decorations.

中文翻译：

---

基于嵌入超薄 Ge2Sb2Te5 吸收层的薄膜腔的高纯度反射式彩色滤光片

通过堆叠金属 - 绝缘体 - 金属（MIM）连续层形成的薄膜腔作为一种无光刻和可扩展的滤色结构具有重要意义。这种空腔可以选择性地透射一定频率范围的入射光，从而产生鲜艳的透射色。然而，具有高纯度和反射率的反射颜色的产生是一个挑战，因为反射模式中的腔谐振吸收窄范围的波长并反射剩余的光谱。_{这项研究表明，通过嵌入超薄 Ge 2} Sb ₂ Te ₅可以获得高纯度和反射性的颜色腔内的层。由于 MIM 结构在绝缘体层上表现出不均匀的强度分布，因此方法是将 Ge ₂ Sb ₂ Te ₅层放置在绝缘体内的高强度区域中，从而在腔谐振模式之外创建另一个吸收带。当与金属层的折射率工程相结合时，这种方法会产生带宽约为 100 nm 和反射效率为 90% 的红色、绿色和蓝色。该研究的结果可以有效地用于许多应用，包括反射式滤色器、比色传感器和表面装饰。