Energy Production and Infrastructure Center (EPIC) [email protected] Metallization & Interconnection Workshop 2017
7th Workshop on Metallization & Interconnection for Crystalline Silicon Solar Cells Energy Production and Infrastructure Center (EPIC)
Abasifreke Ebong, Nirupama Bezawada, Veysel Unsur, Ren Keming and Ahrar Chowdhury
Department of Electrical and Computer Engineering University of North Carolina at Charlotte
9201 University City Blvd, Charlotte NC 28223-0001, USA
Energy Production and Infrastructure Center (EPIC) [email protected] Metallization & Interconnection Workshop 2017
7th Workshop on Metallization & Interconnection for Crystalline Silicon Solar Cells Energy Production and Infrastructure Center (EPIC)
2
(i) R1 – metal-semiconductor back contact (ii) R2 – bulk semiconductor (iii) R3 – emitter between two gridlines (iv) R4 – metal – semiconductor – contact on gridline (v) R5 – gridline (vi) R6 - busbar
Energy Production and Infrastructure Center (EPIC) [email protected] Metallization & Interconnection Workshop 2017
7th Workshop on Metallization & Interconnection for Crystalline Silicon Solar Cells
1970; 20 1980; 25
1990; 35 1995; 40
2000; 45 2005; 50
2008; 55 2011; 60
2012; 65 2013; 70
2014; 75 2015; 80
2016; 90
2017; 100
2019; 110
2021; 120
2024; 130 2027; 130
20
40
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140
1970 1980 1990 2000 2010 2020 2030
Shee
t Res
ista
nce
(ohm
/sq.
)
Year
ITRPV 2017 Expected trend for sheet resistance
Energy Production and Infrastructure Center (EPIC) [email protected] Metallization & Interconnection Workshop 2017
7th Workshop on Metallization & Interconnection for Crystalline Silicon Solar Cells
Energy Production and Infrastructure Center (EPIC) [email protected] Metallization & Interconnection Workshop 2017
7th Workshop on Metallization & Interconnection for Crystalline Silicon Solar Cells
1970; 200
1980; 180
1990; 160
2000; 140
2005; 120
2010; 100
2015; 70
2016; 48 2017; 45
2019; 38 2021; 30 2024; 30
2027; 25 20
40
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1970 1980 1990 2000 2010 2020 2030
Grid
line
wid
th (u
m)
Year
ITRPV 2017 Expected trend for gridline width
Energy Production and Infrastructure Center (EPIC) [email protected] Metallization & Interconnection Workshop 2017
7th Workshop on Metallization & Interconnection for Crystalline Silicon Solar Cells
2-5%
85-90% 5-10%
[1] R. Prunchak, US patent 7,736,546B2, 2010. [2] Carroll et al, US Patent, 8,889,980 B2 [3] R. G. Rajendran, US 2013/0099177 A1
Energy Production and Infrastructure Center (EPIC) [email protected] Metallization & Interconnection Workshop 2017
7th Workshop on Metallization & Interconnection for Crystalline Silicon Solar Cells
p.7
(i) 𝑆𝑆(𝑤𝑤𝑤𝑤𝑤) + 2𝑃𝑃𝑂(𝑔𝑔𝑤𝑔𝑔) → 𝑆𝑆𝑂2(𝑔𝑔𝑤𝑔𝑔) + 2𝑃𝑃 (ii) 𝑆𝑆(𝑤𝑤𝑤𝑤𝑤) + 2𝐴𝐴2𝑂(𝑔𝑔𝑤𝑔𝑔) → 𝑆𝑆𝑂2 (𝑔𝑔𝑤𝑔𝑔) + 4𝐴𝐴 (iii)𝑆𝑆3𝑁4(𝑑𝑑𝑤𝑔𝑤𝑑𝑑𝑤𝑑𝑑 𝑜𝑜 𝑤𝑤𝑤𝑤𝑤) + 6𝐴𝐴2𝑂(𝑔𝑔𝑤𝑔𝑔) → 3𝑆𝑆𝑂2 (𝑔𝑔𝑤𝑔𝑔) +
12𝐴𝐴 + 2𝑁2 ↑
[1] C. Ballif, et al, App. Phys. Lett., 82 (12), 1878-1880, 2003.
[2] Schubert et al, Solar Energy Materials and Solar Cells, 90, 33399-3406, 2006.
[3] Hilali et al, J. Electrochem. Soc. 153, A5, 2006.
[4] Li et al, J. Appl. Phys. 105, 066102, 2009
[5] Eberstein et al, Energy Proceedia 27, 522-530, 2012.
[6] Tai et al, RSC Advances, 5, 92515-92521, 2015
Energy Production and Infrastructure Center (EPIC) [email protected] Metallization & Interconnection Workshop 2017
7th Workshop on Metallization & Interconnection for Crystalline Silicon Solar Cells
p.8
TEM micrograph: overfired Ag/Si contact. The intermediate SiNx
layer has been dissolved in the firing process.
Ballif et al : Appl. Phys. Lett., Vol. 82, No. 12, 24 March 2003
Energy Production and Infrastructure Center (EPIC) [email protected] Metallization & Interconnection Workshop 2017
7th Workshop on Metallization & Interconnection for Crystalline Silicon Solar Cells
p.9
SEM-picture of the interface of a silver thick film-finger on [1 0 0] orientated silicon. Silver crystallites grown into the silicon are clearly visible.
Schubert et al., Solar Energy Materials & Solar Cells 90 (2006) 3399–3406
Energy Production and Infrastructure Center (EPIC) [email protected] Metallization & Interconnection Workshop 2017
7th Workshop on Metallization & Interconnection for Crystalline Silicon Solar Cells
SEM micrographs of: contact layer, finger layer, full layer and elemental analysis
Si
Ag Crystallites
Contact and Finger layers
Ag Crystallites
Contact layers Top view of contact and finger layers after sintering
Energy Production and Infrastructure Center (EPIC) [email protected] Metallization & Interconnection Workshop 2017
7th Workshop on Metallization & Interconnection for Crystalline Silicon Solar Cells
p.11
Paste particle size Series Resistance (Ω-cm2)
Contact Resistance (Ω-cm2)
Fill factor
(%) Paste ID D10 D50 D90
A 1.273 2.102 3.466 13.813 0.825 43.4 B 1.125 2.031 3.657 0.812 0.442 78.4 C 1.194 2.145 3.784 0.737 0.390 78.8 D 1.205 2.085 3.568 0.638 0.312 79.4 E 1.208 2.029 3.506 1.737 0.774 73.8 F 1.238 2.056 3.366 1.829 0.552 73.5 G 1.182 2.032 3.437 1.983 1.099 73.1 H 1.159 2.062 3.628 1.107 0.334 76.9 I 1.159 1.914 3.100 2.321 0.929 71.1 J 1.140 2.066 3.761 0.874 0.222 78.2 K 1.171 2.060 3.579 4.263 0.906 63.6 L 1.150 2.028 3.518 6.703 1.018 56.1
CP 1.545 3.456 4.965 5.876 0.967 60.3
Energy Production and Infrastructure Center (EPIC) [email protected] Metallization & Interconnection Workshop 2017
7th Workshop on Metallization & Interconnection for Crystalline Silicon Solar Cells Energy Production and Infrastructure Center (EPIC)
Contact characterization
SEM/EDX for Ag paste D and J after drying at 200oC for 2-mins
Paste D 34/66 PbO/TeO2
Paste J 50/50 Pbo/TeO2
Energy Production and Infrastructure Center (EPIC) [email protected] Metallization & Interconnection Workshop 2017
7th Workshop on Metallization & Interconnection for Crystalline Silicon Solar Cells Energy Production and Infrastructure Center (EPIC)
EDX analyses of Contact
Paste J Paste D
Element Wt% At% CK 43.92 77.82 OK 06.10 08.12 MgK 03.62 03.17 AlK 02.81 02.22 SiK 03.86 02.92 PbM 13.51 01.39 TeL 26.19 04.37 Matrix Correction ZAF
Element Wt% At% CK 53.34 82.10 OK 07.53 08.70 MgK 03.39 02.58 SiK 04.52 02.97 PbM 15.72 01.40 TeL 15.50 02.25 Matrix Correction ZAF
After 2-min drying at 200oC
Energy Production and Infrastructure Center (EPIC) [email protected] Metallization & Interconnection Workshop 2017
7th Workshop on Metallization & Interconnection for Crystalline Silicon Solar Cells Energy Production and Infrastructure Center (EPIC)
Si
Ag + Pb + Te
K_C
ou
nt
Contact characterization
Paste J
K_C
ou
nt
Ag + Te + Pb
Si
SEM/EDX for Ag paste D and J after contact co-firing at 815oC peak firing temperature in IR belt furnace.
Paste D
Energy Production and Infrastructure Center (EPIC) [email protected] Metallization & Interconnection Workshop 2017
7th Workshop on Metallization & Interconnection for Crystalline Silicon Solar Cells Energy Production and Infrastructure Center (EPIC)
EDX analyses of Contact Paste J
After contact co-firing at 815oC peak firing temperature in IR belt furnace.
Paste D
Energy Production and Infrastructure Center (EPIC) [email protected] Metallization & Interconnection Workshop 2017
7th Workshop on Metallization & Interconnection for Crystalline Silicon Solar Cells Energy Production and Infrastructure Center (EPIC)
Contact characterization
0
50
100
150
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350
30 40 50 60 70 80 90 100
Co
un
t p
er S
ec
2θ (degree)
Paste D after 200oC dry
Paste D after 815oC sinteringSi peak
(111)
(200)(220)
(311)
(222)0
50
100
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Coun
ts p
er s
ec
2Ѳ (degree)
Paste J after 200oC dry
Paste J after 815oC firing
(111)
(200)
(220)
Si Peak(311)
(222)
XRD pattern for Ag paste D and J after drying at 200oC for 2-mins and after contact co-firing at 815oC peak firing temperature in IR belt furnace. Before: All Ag phases are similar After: (111) phase in D doubles due to PbO/TeO2 ratio difference
Paste D Paste J
Energy Production and Infrastructure Center (EPIC) [email protected] Metallization & Interconnection Workshop 2017
7th Workshop on Metallization & Interconnection for Crystalline Silicon Solar Cells Energy Production and Infrastructure Center (EPIC)
Raman Spectra of contact
100 200 300 400 500 600 700 800 900 1000
100020003000400050006000700080009000
100001100012000130001400015000
124-
D-H
NO
3-1
Wavenumber
124-D-HNO3-1 124-D-HNO3-2 124-D-HF-1 124-D-HF-2
Paste D
Inte
nsity
Ag2Te
TeO2
Si
Energy Production and Infrastructure Center (EPIC) [email protected] Metallization & Interconnection Workshop 2017
7th Workshop on Metallization & Interconnection for Crystalline Silicon Solar Cells
p.18
1. Nano-sized metallic Zn additives - uniformly etch the non-conductive SiNx:H layer
2. TeO2 additive - uniform etching of siNx:H layer - Decreases viscosity of molten glass and causes uniform wetting of SiNx:H - No Te after glass removal with HF (i) Ag, Te and Si form Ag-Te, Ag-Si and Ag-Te-Si alloys.
(ii) Formation of Ag2Te – a semimetal increases conductivity of glass – low contact resistance and gridline resistance.
3. Both 66PbO-34TeO2 and the 50PbO-50TeO2 glasses enable higher isothermal conductivity. The resulting low melting nature of the glass facilitate diffusion process introducing ionic conductivity leading to high isothermal conductivity.
1. Li et al., J. Appl. Phys. 110, 074304 (2011) 2. Ionkin et al, ACS Appl. Mater. Interfaces 3, 606 (2011) 3. Ebong et al, JJAP, 56, 08MB07 (2017) 4. ] R. Prunchak, US patent 7,736,546B2, 2010 5. Vithal et al., J. Appl. Phys. 81 (12), 7922-7926, (1997)
Energy Production and Infrastructure Center (EPIC) [email protected] Metallization & Interconnection Workshop 2017
7th Workshop on Metallization & Interconnection for Crystalline Silicon Solar Cells Energy Production and Infrastructure Center (EPIC)
Abasifreke Ebong, Nirupama Bezawada, Veysel Unsur, Ren Keming and Ahrar Chowdhury
Department of Electrical and Computer Engineering University of North Carolina at Charlotte
9201 University City Blvd, Charlotte NC 28223-0001, USA
Energy Production and Infrastructure Center (EPIC) [email protected] Metallization & Interconnection Workshop 2017
7th Workshop on Metallization & Interconnection for Crystalline Silicon Solar Cells Energy Production and Infrastructure Center (EPIC)
• Belt speed: 230 pm • Peak Temp: 815oC