Color arrestor pixels for high-fidelity, high-sensitivity imaging sensors

Area of Science:

• Optoelectronics
• Materials Science
• Nanotechnology

Background:

• Silicon (Si) is the standard material for complementary metal-oxide-semiconductor (CMOS) imaging devices due to its favorable properties.
• Miniaturization in CMOS image sensors leads to challenges like crosstalk and reduced optical efficiency, particularly with silicon's poor long-wavelength absorption.
• Optical metasurfaces offer potential solutions to overcome intrinsic material limitations in imaging.

Purpose of the Study:

• To introduce a novel class of color image sensors, termed color arrestor pixels (CAPs).
• To design CAPs with spectral responses that precisely replicate the human eye's color perception.
• To demonstrate improved color accuracy compared to existing red-green-blue filter and metasurface-based sensors.

Main Methods:

• Development of CAPs utilizing linearly independent combinations of standardized color matching functions.
• Fabrication of CAPs with a small footprint (860 nm height, 221 nm pixel pitch).
• Evaluation of color reproduction accuracy using the Gretag-Macbeth chart under standard illuminant D65 and assessment of absorption efficiencies at key wavelengths.

Main Results:

• CAPs achieved an average CIEDE2000 color difference of 1.79 for 24 colors, indicating high color accuracy.
• Demonstrated exceptional color reproduction fidelity across various spectral illuminations due to mimicking human eye response.
• Exhibited high absorption efficiencies (79% at 452 nm, 81% at 544 nm, 63% at 603 nm) and good angular tolerance.

Conclusions:

• CAPs represent a significant advancement in color image sensor technology by directly matching human visual perception.
• The proposed design overcomes the limitations of traditional silicon-based sensors, particularly in color accuracy and spectral response.
• CAPs offer a promising new direction for research and applications in high-fidelity optical image sensing.