Process and optical modeling of black silicon

Area of Science:

• Materials Science
• Nanotechnology
• Photovoltaics

Background:

• Black silicon is crucial for the photovoltaic industry, aiming for surfaces with minimal reflection and defects.
• Achieving a low-defect front surface is a key objective for enhancing solar cell efficiency.

Purpose of the Study:

• To fabricate and characterize black silicon surfaces with low reflectance and low defect density.
• To develop modeling tools that accurately predict the geometric features of fabricated black silicon based on process parameters.

Main Methods:

• Fabrication of black silicon samples using reactive ion etching (RIE) followed by chemical etching for surface smoothing.
• Characterization of fabricated samples to assess geometric features and optical properties.
• Development and application of rigorous coupled wave analysis (RCWA)-based modeling to simulate reflectance.

Main Results:

• Successful fabrication of black silicon samples with reduced reflectance.
• Development of modeling tools capable of reproducing experimental geometric features.
• Achieved good agreement between simulated and experimental reflectance, with better accuracy using a 0.5 square microns sample model.
• Identified an optimal balance between low reflectance and minimal material thickness.

Conclusions:

• The combined RIE and chemical etching process effectively produces low-reflectance black silicon.
• The developed modeling tools provide accurate predictions of surface geometry and reflectance.
• An optimal trade-off between low reflectance and low thickness was achieved, beneficial for photovoltaic applications.