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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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Thanks for your attention!!

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