Self-assembled metal-oxide nanoparticles on GaAs: infrared absorption enabled by localized surface plasmons

• Published in: Nanophotonics (Berlin, Germany) Vol. 10; no. 9; pp. 2509 - 2518
• Main Authors: Martínez Castellano, Eduardo, Tamayo-Arriola, Julen, Montes Bajo, Miguel, Gonzalo, Alicia, Stanojević, Lazar, Ulloa, Jose María, Klymov, Oleksii, Yeste, Javier, Agouram, Said, Muñoz, Elías, Muñoz-Sanjosé, Vicente, Hierro, Adrian
• Format: Journal Article
• Language: English
• Published: Berlin De Gruyter 01-07-2021; Walter de Gruyter GmbH
• Subjects: CdO; Coupled modes; Electromagnetic absorption; Infrared absorption; intersubband transition; Intersubband transitions; localized surface plasmon; Luminous intensity; Metal oxides; metal-oxide; Nanoparticles; Photometers; Plasmons; Polarization; Power gain; quantum well; Quantum well infrared photodetectors; Self-assembly; Surface chemistry
• ISSN: 2192-8606; 2192-8614
• DOI: 10.1515/nanoph-2021-0167

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
-polarization the intersubband absorption is enhanced by a factor of 2.5 and is still observed under
-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.