Tunnel oxide passivated contacts formed by ion implantation for applications in silicon solar cells

Journal Article · Sat Nov 28 00:00:00 EST 2015 · Journal of Applied Physics

DOI:https://doi.org/10.1063/1.4936223· OSTI ID:22492985

Reichel, Christian ^[1]; Feldmann, Frank; Müller, Ralph; Hermle, Martin; Glunz, Stefan W. ^[1]; Reedy, Robert C.; Lee, Benjamin G.; Young, David L.; Stradins, Paul ^[2]

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1. Fraunhofer Institute for Solar Energy Systems (ISE), Heidenhofstrasse 2, 79110 Freiburg (Germany)
2. National Renewable Energy Laboratory (NREL), 15013 Denver West Parkway, Golden, Colorado 80401 (United States)

Passivated contacts (poly-Si/SiO{sub x}/c-Si) doped by shallow ion implantation are an appealing technology for high efficiency silicon solar cells, especially for interdigitated back contact (IBC) solar cells where a masked ion implantation facilitates their fabrication. This paper presents a study on tunnel oxide passivated contacts formed by low-energy ion implantation into amorphous silicon (a-Si) layers and examines the influence of the ion species (P, B, or BF{sub 2}), the ion implantation dose (5 × 10{sup 14 }cm{sup −2} to 1 × 10{sup 16 }cm{sup −2}), and the subsequent high-temperature anneal (800 °C or 900 °C) on the passivation quality and junction characteristics using double-sided contacted silicon solar cells. Excellent passivation quality is achieved for n-type passivated contacts by P implantations into either intrinsic (undoped) or in-situ B-doped a-Si layers with implied open-circuit voltages (iV{sub oc}) of 725 and 720 mV, respectively. For p-type passivated contacts, BF{sub 2} implantations into intrinsic a-Si yield well passivated contacts and allow for iV{sub oc} of 690 mV, whereas implanted B gives poor passivation with iV{sub oc} of only 640 mV. While solar cells featuring in-situ B-doped selective hole contacts and selective electron contacts with P implanted into intrinsic a-Si layers achieved V{sub oc} of 690 mV and fill factor (FF) of 79.1%, selective hole contacts realized by BF{sub 2} implantation into intrinsic a-Si suffer from drastically reduced FF which is caused by a non-Ohmic Schottky contact. Finally, implanting P into in-situ B-doped a-Si layers for the purpose of overcompensation (counterdoping) allowed for solar cells with V{sub oc} of 680 mV and FF of 80.4%, providing a simplified and promising fabrication process for IBC solar cells featuring passivated contacts.

• OSTI ID: 22492985
• Journal Information: Journal of Applied Physics, Vol. 118, Issue 20; Other Information: (c) 2015 AIP Publishing LLC; Country of input: International Atomic Energy Agency (IAEA); ISSN 0021-8979
• Country of Publication: United States
• Language: English

Related Subjects

75 CONDENSED MATTER PHYSICS
SUPERCONDUCTIVITY AND SUPERFLUIDITY
71 CLASSICAL AND QUANTUM MECHANICS
GENERAL PHYSICS
BORON FLUORIDES
BORON IONS
DOPED MATERIALS
ELECTRIC CONTACTS
ELECTRIC POTENTIAL
ELECTRONS
FILL FACTORS
ION IMPLANTATION
PASSIVATION
PHOSPHORUS IONS
SILICON OXIDES
SILICON SOLAR CELLS
TEMPERATURE RANGE 0400-1000 K