TY - JOUR

T1 - Influence of the boron emitter profile on VOC and JSC losses in fully ion implanted n-type PERT solar cells

AU - Kiefer, Fabian

AU - Peibst, Robby

AU - Ohrdes, Tobias

AU - Dullweber, Thorsten

AU - Krügener, Jan

AU - Osten, H. Jörg

AU - Schöllhorn, Claus

AU - Grohe, Andreas

AU - Brendel, Rolf

PY - 2015/2

Y1 - 2015/2

N2 - In this work, we report on fully ion implanted 156 × 156mm2 n-type PERT solar cells fabricated in an industry-capable process. The implant damage of phosphorous and boron was coannealed in a single furnace annealing step. The cells feature a screen-printed front side metallization and an evaporated rear side metallization. The influence of boron emitter profile on the open-circuit voltage VOC and the short-circuit current density JSC was studied by comparing two boron doses (2.5×1015cm-2, 3×1015cm-2) and two annealing durations (20 min, 80 min). The solar cells reach tightly distributed efficiencies above 20% (20.3% maximum). Cells featuring an emitter implanted with 2.5×1015 cm-2 boron dose annealed for 80 min show the highest open-circuit voltages up to 668mV. As compared to implied open-circuit voltages measured on non-metallized cell precursors, this corresponds to a metallization-induced voltage loss of 14mV. For the shorter annealing time (corresponding to a shallower profile) but same boron dose, the VOC loss is 18mV. The fact that the cells with the higher boron dose of 3×1015cm-2 showed lower VOC values indicates that the recombination at the Ag/Al-p+ Si contacts is not totally dominating. We determine the recombination current densities of the metallized emitter regions to 900-1900 fAcm-2. Contrary to the dependence of VOC on the emitter profile, JSC is lower for deeper emitters. The loss in JSC is visible in the internal quantum efficiencies IQE at short wavelengths. Strategies for an optimization of both quantities, JSC and VOC, are discussed.

AB - In this work, we report on fully ion implanted 156 × 156mm2 n-type PERT solar cells fabricated in an industry-capable process. The implant damage of phosphorous and boron was coannealed in a single furnace annealing step. The cells feature a screen-printed front side metallization and an evaporated rear side metallization. The influence of boron emitter profile on the open-circuit voltage VOC and the short-circuit current density JSC was studied by comparing two boron doses (2.5×1015cm-2, 3×1015cm-2) and two annealing durations (20 min, 80 min). The solar cells reach tightly distributed efficiencies above 20% (20.3% maximum). Cells featuring an emitter implanted with 2.5×1015 cm-2 boron dose annealed for 80 min show the highest open-circuit voltages up to 668mV. As compared to implied open-circuit voltages measured on non-metallized cell precursors, this corresponds to a metallization-induced voltage loss of 14mV. For the shorter annealing time (corresponding to a shallower profile) but same boron dose, the VOC loss is 18mV. The fact that the cells with the higher boron dose of 3×1015cm-2 showed lower VOC values indicates that the recombination at the Ag/Al-p+ Si contacts is not totally dominating. We determine the recombination current densities of the metallized emitter regions to 900-1900 fAcm-2. Contrary to the dependence of VOC on the emitter profile, JSC is lower for deeper emitters. The loss in JSC is visible in the internal quantum efficiencies IQE at short wavelengths. Strategies for an optimization of both quantities, JSC and VOC, are discussed.

KW - Boron emitters

KW - Ion implantation

KW - Silicon

KW - Solar cells

UR - http://www.scopus.com/inward/record.url?scp=85027924305&partnerID=8YFLogxK

U2 - 10.1002/pssa.201431118

DO - 10.1002/pssa.201431118

M3 - Article

AN - SCOPUS:85027924305

VL - 212

SP - 291

EP - 297

JO - Physica Status Solidi (A) Applications and Materials Science

JF - Physica Status Solidi (A) Applications and Materials Science

SN - 1862-6300

IS - 2

ER -