Abstract
We fabricate and measure graded-index "black silicon" surfaces and find the underlying scaling law governing reflectance. Wet etching (100) silicon in HAuCl4, HF, and H2 O2 produces Au nanoparticles that catalyze formation of a network of [100]-oriented nanopores. This network grades the near-surface optical constants and reduces reflectance to below 2% at wavelengths from 300 to 1000 nm. As the density-grade depth increases, reflectance decreases exponentially with a characteristic grade depth of about 1/8 the vacuum wavelength or half the wavelength in Si. Observation of Au nanoparticles at the ends of cylindrical nanopores confirms local catalytic action of moving Au nanoparticles.
Original language | American English |
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Article number | Article No. 231121 |
Number of pages | 3 |
Journal | Applied Physics Letters |
Volume | 94 |
Issue number | 23 |
DOIs | |
State | Published - 2009 |
NREL Publication Number
- NREL/JA-520-45395
Keywords
- photovoltaic cells
- reflectance