Surface Passivation of Crystalline

crashclappergapSoftware and s/w Development

Dec 13, 2013 (3 years and 9 months ago)

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Surface Passivation of Crystalline
Silicon Solar Cells: A Review

Armin G.
Aberle

Progress in
P
hotovoltaics
: Research and
Application 8,473
-
487,2000.



2010/8/27

2
/5

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GPL

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
S
i solar cell


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









Low recombination rate strategy


1. low surface state
N
st


2. low carrier concentration n
s
,
p
s

E
t

E
c

E
v

Surface

Recombination

rate:



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Reduction of the surface states


Growth/deposition of a dielectric film


SiO
2


Al
2
O
3


SiN
x


Antireflective coating layer





Chemical methods


HF immersion


Alcoholic solution

Si solar cell

Dielectric layer(d)

n
d
4




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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


The fixed charge induced the negative charge on the surface,
bending the band diagram.


Al
2
O
3

is suitable to p
-
type Si substrate.

Al
2
O
3

+

+

+

+

+

+

-

-

-

-

-

-

e
-

h
+



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/5

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PERL solar cells


Passivated Emitter and Rear Locally Diffused Solar
Cell
(24.7%)



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/5

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Band offset measurement


The
S
i substrate can passivated by dielectric film and electric
field effect method.


The Al
2
O
3

is suitable for p
-
type Si substrate passivation, and
the SiN
x

is suitable for n
-
type Si substrate passivation.

Thanks for your attention!!