Metal-oxides hold promise as superior plasmonic materials in the mid-infrared compared to metals, although their integration over established material technologies still remains challenging. We demonstrate localized surface plasmons in self-assembled, hemispherical CdZnO metal-oxide nanoparticles on GaAs, as a route to enhance the absorption in mid-infrared photodetectors. In this system, two localized surface plasmon modes are identified at 5.3 and 2.7 μm, which yield an enhancement of the light intensity in the underlying GaAs. In the case of the long-wavelength mode the enhancement is as large as 100 near the interface, and persists at depths down to 50 nm. We show numerically that both modes can be coupled to infrared intersubband transitions in GaAs-based multiple quantum wells, yielding an absorbed power gain as high as 5.5, and allowing light absorption at normal incidence. Experimentally, we demonstrate this coupling in a nanoparticle/multiple quantum well structure, where under p -polarization the intersubband absorption is enhanced by a factor of 2.5 and is still observed under s -polarization, forbidden by the usual absorption selection rules. Thus, the integration of CdZnO on GaAs can help improve the figures of merit of quantum well infrared photodetectors, concept that can be extended to other midinfrared detector technologies.

中文翻译：

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GaAs 上的自组装金属氧化物纳米颗粒：局部表面等离子体激发红外吸收

与金属相比，金属氧化物有望成为中红外领域的优质等离子体材料，尽管它们与现有材料技术的集成仍然具有挑战性。我们在 GaAs 上的自组装半球形 CdZnO 金属氧化物纳米粒子中展示了局部表面等离子体，作为增强中红外光电探测器吸收的途径。在该系统中，在 5.3 和 2.7 μm 处识别出两种局部表面等离子体模式，这会增强底层 GaAs 中的光强度。在长波长模式的情况下，界面附近的增强高达 100，并持续到 50 nm 的深度。我们在数值上表明，两种模式都可以与基于 GaAs 的多量子阱中的红外子带间跃迁耦合，产生高达 5.5 的吸收功率增益，并允许在法向入射时吸收光。通过实验，我们在纳米粒子/多量子阱结构中证明了这种耦合，其中在 p 极化下，子带间吸收增强了 2.5 倍，并且在 s 极化下仍然可以观察到，这是通常的吸收选择规则所禁止的。因此，在 GaAs 上集成 CdZnO 有助于提高量子阱红外光电探测器的品质因数，这一概念可以扩展到其他中红外探测器技术。