Miniaturizing color-sensitive photodetectors via hybrid nanoantennas toward submicrometer dimensions

Abstract

Digital camera sensors use color filters on photodiodes to achieve color selectivity. As the color filters and photosensitive silicon layers are separate elements, these sensors suffer from optical cross-talk, which sets limits to the minimum pixel size. Here, we report hybrid silicon-aluminum nanostructures in the extreme limit of zero distance between color filters and sensors. This design could essentially achieve submicrometer pixel dimensions and minimize the optical cross-talk arising from tilt illuminations. The designed hybrid silicon-aluminum nanostructure has dual functionalities. Crucially, it supports a hybrid Mie-plasmon resonance of magnetic dipole to achieve color-selective light absorption, generating electron hole pairs. Simultaneously, the silicon-aluminum interface forms a Schottky barrier for charge separation and photodetection. This design potentially replaces the traditional dye-based filters for camera sensors at ultrahigh pixel densities with advanced functionalities in sensing polarization and directionality, and UV selectivity via interband plasmons of silicon.

Review on III–V Semiconductor Nanowire Array Infrared Photodetectors

“…[98] Ho et al demonstrated a hybrid Si-Al nanostructure-based Schottky detector, for visible color-selective detection due to the Mieplasmon resonance of magnetic dipole supported in such hybrid nanoantennas. [99] By utilizing such concept, there might also have a strong possibility on III-V semiconductor nanowire arraybased Schottky photodetectors to further extend the detection range and improve the performance.…”

Advances in Meta-Optics and Metasurfaces: Fundamentals and Applications

“…Previous efforts often focused on metallic metasurfaces [ 67 , 68 , 69 , 70 , 71 , 72 , 73 , 74 , 75 , 76 , 77 ], which can enhance light–matter interactions and introduce versatile control of incoming light by activating local plasmonic resonance, albeit with limited efficiency due to ohmic loss [ 78 , 79 , 80 , 81 , 82 , 83 ]. Dielectric metasurfaces overcome the limitation of metallic metasurfaces, which have provided a promising way to develop highly efficient and multi-functional meta-devices [ 84 , 85 , 86 , 87 , 88 , 89 , 90 , 91 , 92 , 93 , 94 , 95 , 96 , 97 , 98 , 99 , 100 ].…”

Nonlocal, Flat-Band Meta-Optics for Monolithic, High-Efficiency, Compact Photodetectors

“…Absorption of light and the conversion of photons into other forms of energy, such as excitons and phonons, have been widely utilized for optical sensing, , imaging, and energy harvesting . Recently, rapid developments in wearable devices and emergence of the Internet of Things have further increased the demand for smaller photodetectors (PDs) with high absorption efficiency. , Compact integrated PDs could potentially provide several advantages for these applications, including high-resolution imaging thanks to the large pixel count, , reduced energy consumption, and high-speed operation . However, two major limitations impede their functionalities: a small device footprint limits the total light collection, and a small device thickness limits the total amount of absorbed light (Figure a).…”

“…In addition, the responsivity of this single-junction meta-optical PD depends on the wavelength and polarization of light, which can be further exploited to create a spectrally selective and polarization-sensitive miniaturized PD. Such multifunctionality can reduce the fabrication costs and optical crosstalk between pixels and have far-reaching impact on wearable sensors, including miniature spectrometers and Li-Fi transducers. − …”

“…Resonant cavity-enhanced absorption occurs as the optical cavity traps light for a longer time period, which increases the absorption efficiency. Various dielectric and plasmonic resonators have been used to enhance the photon-to-electron conversion efficiency of PDs in silicon ,, and other materials. − However, these results all focus on normal incident light and thus are incompatible with lens-based concentrators (Figure b), as focused light contains a wide range of incidence angles. Therefore, an angle-independent resonant cavity can both enhance the light absorption and be compatible with a light concentrator to enhance the photoresponsivity (Figure c).…”