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Optical Absorption Enhancement in SiliconNanohole Arrays for Solar Photovoltaics
Reporter: Bo-Yu HuangAdvisor: Peichen Yu
Green Phtonics Lab., National Chiao Tung University
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Sang Eon Han and Gang Chen*Department of Mechanical Engineering, Massachusetts Institute of
Technology, Cambridge, Massachusetts 02139
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Outline
Introduction Nanorod arrays Nanohole arrays
Simulation & Discussion
Summary
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Introduction
Poor infrared absorption of crystalline silicon (indirect band gap)
200-300 µm c-Si active layers that absorb light efficiently This thickness accounts for 40% of the total cost∼
An effective technique for light trapping in thin active layers needs to be developed
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Introduction
Nanorod arrays Construct a p-n or a p-i-n junction in the radial direction of
each nanorod Shorten the carrier diffusion length Anti-reflection
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Introduction
Nanohole arrays We find that nanohole arrays are comparable to or
even better than nanorod arrays in terms of light absorption.
Clean wafer Spin coated nanoshpere Reduce nanosphere
Deposit mask metalDry etchingRemove mask metal
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Introduction
Silicon nanohole arrays exhibit better absorption and mechanical robustness
Applied physics letter, 96, 181903 (2010)
Nano letters,10, 1082 (2010) JACS, 132, 6872 (2010)
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Simulation & Discussion
For rod:Filling fraction=
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Simulation & Discussion
Absorption is higher for the nanohole array when λ is less than approximately 750 nm
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Simulation & Discussion
thickness is 2.33 µm
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Summary
We have presented the optical properties of c-Si nanohole array structures and found that their absorption is better than nanorod arrays.
Nanohole array structure requiring one-twelfth the c-Si mass and one-sixth the thickness of a standard 300 µm Si wafer.
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