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Document Type

Thesis - University Access Only

Award Date

2014

Degree Name

Master of Science (MS)

Department / School

Electrical Engineering and Computer Science

First Advisor

Qi Hua Fan

Second Advisor

David Galipeau

Abstract

Photovoltaics (PV) can directly convert solar energy into electricity without environmental pollution as no combustion or fuel is required. Poly-Si has emerged as a suitable material for photovoltaics due to its lower cost and ease of fabrication and can be used in many optoelectronic devices due to lower reflection losses and photoluminescence behavior. Porous poly-Si can be achieved by spark erosion technique or stain etching technique; however, these methods do not have high repeatability or control of pore size. Electrochemical anodization of poly-Si substrate in an electrolyte solution of hydrofluoric acid (HF) has become a common technique; however, the main disadvantage is that HF is highly toxic and corrosive. The objective of this thesis was to develop a non-toxic and cost-effective electrochemical anodization technique to achieve highly ordered porous structure in polycrystalline silicon for antireflection with total reflectance less than 5%. Electrochemical anodization was used to fabricate the uniform porous structure in an aqueous electrolyte composed of orthophosphoric acid, ammonium fluoride, and deionized (DI) water. A non-HF aqueous electrolyte was successfully developed for the first time, which, combined with the anodization parameters (current, voltage, and time), allows controlled formation of uniform porous morphology in poly-Si. The porous structure so formed by non-toxic electrochemical anodization technique can be used in solar cells as broadband antireflection. The photoluminescence shown by porous poly-Si has opened a path for electroluminescent devices. Future work should include: 1) using porous silicon with reflectance lower than 6% for solar cell fabrication; 2) investigating the effect of pore morphology on photoluminescence of porous silicon; and 3) investigating the effect of pore morphology on Raman shift of porous silicon.

Library of Congress Subject Headings

Porous silicon
Optoelectronic devices
Silicon crystals

Description

Includes bibliographical references (pages 66-75).

Format

application/pdf

Number of Pages

86

Publisher

South Dakota State University

Rights

In Copyright - Non-Commercial Use Permitted
http://rightsstatements.org/vocab/InC-NC/1.0/

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