Local rear contacts to silicon solar cells by in-line high-rate evaporation of aluminum

authored by

Christoph Mader, Jens Müller, Stefan Eidelloth, Rolf Brendel

Abstract

We contact p-type wafers and boron-diffused layers by laser ablation of a passivating aluminum oxide and silicon nitride stack and subsequent in-line high-rate evaporation of aluminum. We measure saturation current densities at the base contacts of 2.5×10 ⁶-1.9×10 ⁷ fA/cm ² for base resistivities of 0.5-3.8 Ω cm and 491-905 fA/cm ² for the contacts to boron-diffused layers of sheet resistances of 23-86 Ω/sq. The contact resistivity of Al layers to p-type silicon with surface doping densities of 4×10 ¹⁵-3×10 ¹⁹ cm ^-3 is in the range of 4-0.1 mΩ cm ², respectively. The measured contact properties allow for the fabrication of highly efficient 'passivated emitter and rear cells' (PERC) and 'passivated emitter and rear totally diffused cells' (PERT). Numerical simulations show that evaporated rear contacts in combination with screen printed contacts at the front allow for energy conversion efficiencies of 20.6% and of 21.1%, for PERC and PERT cells, respectively. The simulated free energy losses show that such cells are not limited by the in-line evaporated point contacts on the rear side.

Organisation(s)

Institute of Solid State Physics

External Organisation(s)

Institute for Solar Energy Research (ISFH)

Type

Article

Journal

Solar Energy Materials and Solar Cells

Volume

107

Pages

272-282

No. of pages

11

ISSN

0927-0248

Publication date

12.2012

Publication status

Published

Peer reviewed

Yes

ASJC Scopus subject areas

Electronic, Optical and Magnetic Materials, Renewable Energy, Sustainability and the Environment, Surfaces, Coatings and Films

Sustainable Development Goals

SDG 7 - Affordable and Clean Energy

Electronic version(s)

https://doi.org/10.1016/j.solmat.2012.06.047 (Access: Closed)