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Document Type

Thesis - University Access Only

Award Date

2013

Degree Name

Master of Science (MS)

Department

Electrical Engineering and Computer Science

First Advisor

Qi Hua Fan

Abstract

In order to minimize the reflection losses, silicon surfaces are textured or antireflection coatings (ARC) are applied on the surface of silicon solar cells. Porous silicon can be achieved by electrochemical anodization of silicon in hydrofluoric acid, but the main disadvantage is that HF is highly toxic and corrosive, which limits its use in industrial applications. So, there is a need for a cost-effective and non-toxic anodization technique to obtain highly ordered (diameter, depth and spacing) and dense porous silicon as a broadband light absorber for PV applications. The objective of this thesis was to develop a non-toxic and cost-effective electrochemical anodization process to achieve highly ordered porous structure for antireflection with less than 5% reflectance. Porous silicon is a silicon crystal with voids. Porous silicon was fabricated using an electrochemical anodization technique where silicon was the anode and platinum was the counter electrode performed at constant voltage and constant current modes. For the constant voltage mode, three, ten, and thirty minute anodized samples exhibited average reflectances of ~6%, ~5% and ~7% respectively in the ultra-violet to the near infra-red regions. For constant current mode, three and ten minute anodized sample had an average reflectance of ~8% and ~7% respectively. While the thirty minute anodized sample had ~7% reflectance from 400-600 nm and ~10% from 600 nm to 1000 nm. All samples exhibited photoluminescence and a shift in the porous silicon Raman peak. This type of porous silicon can be used as antireflective coatings in industrial solar cell processing as a replacement for commonly use chemical vapor deposited antireflection coatings which have a reflectance of 10%. Future work can include optimization of anodization parameters to obtain pores with controllable geometry (diameter, depth, spacing) and studies of the effect of pore morphology on photoluminescence.

Library of Congress Subject Headings

Porous silicon
Reflectance
Photovoltaic power generation

Description

Includes bibliographical references (pages 73-86).

Format

application/pdf

Number of Pages

98

Publisher

South Dakota State University

Rights

In Copyright - Educational Use Permitted
http://rightsstatements.org/vocab/InC-EDU/1.0/

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