TY - JOUR

T1 - Structural Investigation of Printed Ag/Al Contacts on Silicon and Numerical Modeling of Their Contact Recombination

AU - Kiefer, Fabian

AU - Krugener, Jan

AU - Heinemeyer, Frank

AU - Osten, Hans-Jörg

AU - Brendel, Rolf

AU - Peibst, Robby

PY - 2016/9

Y1 - 2016/9

N2 - Ag/Al pastes allow for a sufficiently low contact resistivity of less than 5 mΩ cm2 with boron-doped p+ emitters. A drawback of those pastes is an enlarged recombination at the silicon/metal interface below those contacts, compared with Ag pastes. For previous Ag/Al pastes from 2013, the observed recombination is even higher than theoretically expected for a fully metal-covered surface. Newly developed Ag/Al pastes allow for a significant reduction of the recombination below the contact, compared with a 2013 Ag/Al paste; for example, the J-{\rm{0e,met}} of an \mathrm{92 \Omega / \text{sq}}. p+ emitter has decreased from 3420 down to 1014 fA/cm2 due to the newly developed paste. For an R-{\rm{sheet}} of 137 Ω/sq, the J-{\rm{0e,met}} is 1399 fA/cm2. Structural investigations of those contacts reveal the microscopic appearance of the contacted region. There are contact spikes of metal grown into the silicon. Those spikes cover 1-1.2% of the entire printed finger area. With values for area fraction and depth of the spikes, we conduct simulations of J-{\rm{0e,met}}. With these simulations, we are able to explain the enlarged recombination at the contact interface and describe the experimentally measured J-{\rm{0e,met}} for both Ag/Al pastes described in this paper.

AB - Ag/Al pastes allow for a sufficiently low contact resistivity of less than 5 mΩ cm2 with boron-doped p+ emitters. A drawback of those pastes is an enlarged recombination at the silicon/metal interface below those contacts, compared with Ag pastes. For previous Ag/Al pastes from 2013, the observed recombination is even higher than theoretically expected for a fully metal-covered surface. Newly developed Ag/Al pastes allow for a significant reduction of the recombination below the contact, compared with a 2013 Ag/Al paste; for example, the J-{\rm{0e,met}} of an \mathrm{92 \Omega / \text{sq}}. p+ emitter has decreased from 3420 down to 1014 fA/cm2 due to the newly developed paste. For an R-{\rm{sheet}} of 137 Ω/sq, the J-{\rm{0e,met}} is 1399 fA/cm2. Structural investigations of those contacts reveal the microscopic appearance of the contacted region. There are contact spikes of metal grown into the silicon. Those spikes cover 1-1.2% of the entire printed finger area. With values for area fraction and depth of the spikes, we conduct simulations of J-{\rm{0e,met}}. With these simulations, we are able to explain the enlarged recombination at the contact interface and describe the experimentally measured J-{\rm{0e,met}} for both Ag/Al pastes described in this paper.

KW - Ag/Al paste

KW - boron emitters

KW - metallization

KW - screen-print contact

UR - http://www.scopus.com/inward/record.url?scp=84981725397&partnerID=8YFLogxK

U2 - 10.1109/jphotov.2016.2591318

DO - 10.1109/jphotov.2016.2591318

M3 - Article

AN - SCOPUS:84981725397

VL - 6

SP - 1175

EP - 1182

JO - IEEE journal of photovoltaics

JF - IEEE journal of photovoltaics

SN - 2156-3381

IS - 5

M1 - 7527615

ER -