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Influence of the boron emitter profile on V OC and J SC losses in fully ion implanted n‐type PERT solar cells
Author(s) -
Kiefer Fabian,
Peibst Robby,
Ohrdes Tobias,
Dullweber Thorsten,
Krügener Jan,
Osten H. Jörg,
Schöllhorn Claus,
Grohe Andreas,
Brendel Rolf
Publication year - 2015
Publication title -
physica status solidi (a)
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.532
H-Index - 104
eISSN - 1862-6319
pISSN - 1862-6300
DOI - 10.1002/pssa.201431118
Subject(s) - common emitter , boron , annealing (glass) , open circuit voltage , materials science , analytical chemistry (journal) , current density , optoelectronics , ion , short circuit , ion implantation , voltage , silicon , chemistry , electrical engineering , composite material , physics , quantum mechanics , organic chemistry , chromatography , engineering
In this work, we report on fully ion implanted 156 × 156 mm 2 n‐type PERT solar cells fabricated in an industry‐capable process. The implant damage of phosphorous and boron was co‐annealed 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 V OC and the short‐circuit current density J SC was studied by comparing two boron doses (2.5 × 10 15 cm −2 , 3 × 10 15 cm −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 × 10 15 cm −2 boron dose annealed for 80 min show the highest open‐circuit voltages up to 668 mV. As compared to implied open‐circuit voltages measured on non‐metallized cell precursors, this corresponds to a metallization‐induced voltage loss of 14 mV. For the shorter annealing time (corresponding to a shallower profile) but same boron dose, the V OC loss is 18 mV. The fact that the cells with the higher boron dose of 3 × 10 15 cm −2 showed lower V OC 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 fA cm −2 . Contrary to the dependence of V OC on the emitter profile, J SC is lower for deeper emitters. The loss in J SC is visible in the internal quantum efficiencies IQE at short wavelengths. Strategies for an optimization of both quantities, J SC and V OC , are discussed.