Back-junction back-contact n-type silicon solar cell with diffused boron emitter locally blocked by implanted phosphorus

Journal Article · Mon Sep 08 00:00:00 EDT 2014 · Applied Physics Letters

DOI:https://doi.org/10.1063/1.4895538· OSTI ID:22310853

Müller, Ralph; Schrof, Julian; Reichel, Christian; Benick, Jan; Hermle, Martin ^[1]

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1. Fraunhofer Institute for Solar Energy Systems, Heidenhofstrasse 2, Freiburg D-79110 (Germany)

The highest energy conversion efficiencies in the field of silicon-based photovoltaics have been achieved with back-junction back-contact (BJBC) silicon solar cells by several companies and research groups. One of the most complex parts of this cell structure is the fabrication of the locally doped p- and n-type regions, both on the back side of the solar cell. In this work, we introduce a process sequence based on a synergistic use of ion implantation and furnace diffusion. This sequence enables the formation of all doped regions for a BJBC silicon solar cell in only three processing steps. We observed that implanted phosphorus can block the diffusion of boron atoms into the silicon substrate by nearly three orders of magnitude. Thus, locally implanted phosphorus can be used as an in-situ mask for a subsequent boron diffusion which simultaneously anneals the implanted phosphorus and forms the boron emitter. BJBC silicon solar cells produced with such an easy-to-fabricate process achieved conversion efficiencies of up to 21.7%. An open-circuit voltage of 674 mV and a fill factor of 80.6% prove that there is no significant recombination at the sharp transition between the highly doped emitter and the highly doped back surface field at the device level.

• OSTI ID: 22310853
• Journal Information: Applied Physics Letters, Vol. 105, Issue 10; Other Information: (c) 2014 AIP Publishing LLC; Country of input: International Atomic Energy Agency (IAEA); ISSN 0003-6951
• Country of Publication: United States
• Language: English

Related Subjects

75 CONDENSED MATTER PHYSICS
SUPERCONDUCTIVITY AND SUPERFLUIDITY
ATOMS
BORON ADDITIONS
CONNECTORS
DIFFUSION
DOPED MATERIALS
EFFICIENCY
ELECTRIC CONTACTS
ELECTRIC POTENTIAL
ENERGY CONVERSION
FILL FACTORS
ION IMPLANTATION
PHOSPHORUS ADDITIONS
PHOTOVOLTAIC EFFECT
RECOMBINATION
SEMICONDUCTOR JUNCTIONS
SILICON
SILICON SOLAR CELLS
SUBSTRATES
SURFACES