People know little about the characteristics of the photonic crystals (PhCs) made of nanoscale building blocks, which can be quite distinct from the usual PhCs made of microscale or even larger units, because the unit size strongly affects the photonic structure. The PhCs made of fluorescent CuInSe₂ quantum dots (QDs) having an ultrasmall average size of 2.2–5.3 nm are studied. The experiments and hybrid density‐functional theory calculation reveal that these QDs have defect‐related fluorescence, and the light absorption exhibits an unexpected indirect‐gap feature because of the discrete and small density of states at the direct‐gap maximum. The frequency‐domain electromagnetic calculations reveal that the PhCs made of the CuInSe₂ QDs have a remarkable out‐of‐plane bandgap in the extreme‐UV (EUV) region. The frequency modes below and above the forbidden gap are separately air band and dielectric band modes. These multifunctional fluorescent semiconductor QD PhCs have application potential in nanoscale photonic devices and EUV photolithography.

中文翻译：

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CuInSe2量子点制成的具有极紫外带隙的发光光子晶体

人们几乎不了解由纳米级构造块制成的光子晶体（PhC）的特性，因为单位大小会严重影响光子结构，因此与通常由微米级甚至更大单位制成的PhC可以完全不同。研究了由具有2.2-5.3 nm超小平均尺寸的荧光CuInSe ₂量子点（QD）制成的PhC。实验和混合密度泛函理论计算表明，这些量子点具有与缺陷相关的荧光，并且光吸收表现出意想不到的间接间隙特征，这是因为在直接间隙最大值处状态的离散和小密度。频域电磁计算表明，由CuInSe ₂制成的PhCQD在极端UV（EUV）区域具有明显的平面外带隙。禁止间隙以下和之上的频率模式分别是空气频带和介电频带模式。这些多功能荧光半导体QD PhC在纳米级光子器件和EUV光刻中具有应用潜力。