Plasmonic wavy surface for ultrathin semiconductor black absorbers

Area of Science:

• Materials Science
• Optoelectronics
• Nanotechnology

Background:

• Efficient light absorption is crucial for various optoelectronic applications.
• Existing absorbers often struggle with broadband performance and polarization/angle dependence.

Purpose of the Study:

• To design and demonstrate a near-unity light absorber with ultra-broadband spectral coverage.
• To investigate the underlying mechanisms responsible for the enhanced absorption.
• To assess the absorber's performance under varying polarization and incident angles.

Main Methods:

• Fabrication of a triple-layer film structure comprising indium tin oxide (ITO), germanium (Ge), and copper (Cu).
• Utilizing a wavy surface geometry to enhance light-matter interaction.
• Characterization of optical absorption properties across the ultraviolet to near-infrared range (300-1100 nm).

Main Results:

• Achieved an average absorption efficiency of 97.7%, demonstrating a 'black absorber'.
• Observed minimal absorption above 90% in the ultra-broadband range of 300-1015 nm.
• Attributed broadband absorption to strong plasmonic resonances and near-field coupling effects.
• Demonstrated stable absorption performance under varying polarization and incident angles.

Conclusions:

• The proposed wavy triple-layer structure enables ultra-broadband, near-perfect light absorption.
• Plasmonic resonances and near-field coupling are key to achieving high and broadband absorption.
• The absorber's robustness to polarization and angle variations makes it suitable for complex environments.
• This work offers a pathway for developing high-performance optoelectronic devices utilizing full-spectrum light absorption.