Low-cost plasma immersion ion implantation doping for Interdigitated back passivated contact (IBPC) solar cells

• Published in: Solar energy materials and solar cells 2016-12, Vol.158 (P1), p.68-76
• Main Authors: Young, David L., Nemeth, William, LaSalvia, Vincenzo, Page, Matthew R., Theingi, San, Aguiar, Jeffery, Lee, Benjamin G., Stradins, Paul
• Format: Article
• Language: English
• Subjects: MATERIALS SCIENCE; Passivated contacts; Plasma immersion ion implantation; Silicon; Solar cells; SOLAR ENERGY
• ISSN: 0927-0248; 1879-3398
• DOI: 10.1016/j.solmat.2016.05.044

We present progress to develop low-cost interdigitated back contact solar cells with pc-Si/SiO2/c-Si passivated contacts formed by plasma immersion ion implantation (PIII). PIII is a lower-cost implantation technique than traditional beam line implantation due to its simpler design, lower operating costs, and ability to run high doses (1E14–1E18 cm−2) at low ion energies (20eV–10keV). These benefits make PIII ideal for high throughput production of patterned passivated contacts, where high-dose, low-energy implantations are made into thin (20–200nm) a-Si layers instead of into the wafer itself. For this work symmetric passivated contact test structures (~100nm thick) grown on n-Cz wafers with pH3 PIII doping gave implied open circuit voltage (iVoc) values of 730mV with Jo values of 2fA/cm2. Samples doped with B2H6 gave iVoc values of 690mV and Jo values of 24fA/cm2, outperforming BF3 doping, which gave iVoc values in the 660–680mV range. Samples were further characterized by SIMS, photoluminescence, TEM, EELS, and post-metallization TLM to reveal micro- and macro-scopic structural, chemical and electrical information. •PIII ion implantation is used to form pc-Si/SiO2 contacts to c-Si solar cells.•N-type Jo < 4 fA/cm2, iVoc ~ 730 mV.•P-type Jo < 35 fA/cm2, iVoc ~690 mV.•EELS data are shown on the passivated contact structure.•Al2O3 is used to passivate the pc-Si/SiO2 contact structure.