Nanocone Metasurface For Omni-Directional Detector And Photovoltaics

Tech ID: 28936 / UC Case 2018-051-0

Patent Status

Patent Pending

Brief Description

Reducing reflection from surfaces is very important for improving the efficiency of solar cells and photodetectors, producing improved optical displays with less glare as well as coatings for high power optical applications. Without anti-reflection (AR), semiconductor surfaces reflect 30-40% of incident light and glass reflects 10-20% even at normal incidence and >70% with large incident angles.

 

Traditional methods for achieving anti-reflection are through thin film AR coating. The traditional AR coating is designed to be a quarter-wavelength in thickness (typically 50-100 nm) and has refractive index equal to the geometric mean of the two refractive indices of the media between which antireflection is desired. Antireflection is achieved using destructive interference and is necessarily a narrow-band and narrow-angle effect. The anti-reflective performance deteriorates as incidence angle increases and is particularly severe beyond 40-50 degrees. This is a major issue in the presence of diffuse light, which is the case in any realistic environment.

 

Researchers at the University of California, Berkeley have developed a novel  Nanocone Metasurface that is able to address what AR coating is unable to do at high incident angles. This method significantly augments the properties of a traditional thin film AR coating. A nanocone array is made of silicon nitride sitting on a thin silicon nitride layer. This underlying layer is similar to a traditional thin film AR coating. Underneath the nanocone metasurface is a indium gallium phosphide absorber. The nanocone metasurface serves as an omni-directional anti-reflection coating thereby collecting light from all directions.


Suggested uses

Solar cells

photo detectors

Advantages

Able to prevent anti-reflection at large incident angles

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Inventors

  • Chang-Hasnain, Connie J.

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