Surface Passivation of Crystalline Silicon Solar Cells: A Review

Report
Surface Passivation of Crystalline
Silicon Solar Cells: A Review
Armin G. Aberle
Progress in Photovoltaics: Research and
Application 8,473-487,2000.
Outline




Introduction
Fundamental physics
Surface passivation method
Surface passivation of c-Si solar cells
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Introduction

Defects
 Extrinsic (Processing related)
 Intrinsic (Si related, unavoidable)

Dangling bond
 Growth condition
 Dislocation
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Surface type in Si solar cell
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Metalized
 Finger and bus bar
 Very high surface recombination
 Avoid recombination loss

Non-metalized
 Illuminated region
 Well passivated and good blue response
 Avoid highly doped

Back electrode
 high surface recombination
 Avoid recombination loss
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Surface recombination

Shockley-Read-Hall (SRH) theory
Surface
Recombination
rate:

Ec
Et
Ev
Low recombination rate strategy
 1. low surface state Nst
 2. low carrier concentration ns, ps
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Reduction of the surface states

Growth/deposition of a dielectric film




SiO2

Al2O3
d 
SiNx
4n
Antireflective coating layer
Dielectric layer(d)
Si solar cell

Chemical methods
 HF immersion
 Alcoholic solution
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Field-effect passivated

High-low junction





p+-p
n+-n
Back surface field (BSF)
Front surface field (FSF)
p-n junction
 MIS
 Selective emitter
 HIT(a-Si)
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Combined passivaction
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Concept
Al2O3
+
+
+
+
+
+
-
e-
h+


The fixed charge induced the negative charge on the surface,
bending the band diagram.
Al2O3 is suitable to p-type Si substrate.
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PERL solar cells

Passivated Emitter and Rear Locally Diffused Solar Cell
(24.7%)
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Band offset measurement


The Si substrate can passivated by dielectric film and electric
field effect method.
The Al2O3 is suitable for p-type Si substrate passivation, and
the SiNx is suitable for n-type Si substrate passivation.
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Thanks for your attention!!

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