Phosphorus-diffused polysilicon contacts for solar cells
Di Yan, Andres Cuevas, James Bullock, Yimao Wan, Christian Samundsett
SOLAR ENERGY MATERIALS AND SOLAR CELLS | ELSEVIER SCIENCE BV | Published : 2015
This paper describes the optimization of a technique to make polysilicon/SiOx contacts for silicon solar cells based on doping PECVD intrinsic polysilicon by means of a thermal POCl3 diffusion process. Test structures are used to measure the recombination current density Joc and contact resistivity ρc of the metal/n+ polysilicon/SiOx/silicon structures. The phosphorus diffusion temperature and time are optimized for a range of thicknesses of the SiOx and polysilicon layers. The oxide thickness is found to be critical to obtain a low contact resistivity ρc, with an optimum of about 1.2 nm for a thermal oxide and ∼1.4 nm for a chemical oxide. A low Joc≤5 fA/cm has been obtained for polysilicon..View full abstract
The authors wish to thank Thomas Allen and Nicholas Grant for fruitful discussions. This work has been supported by the Australian Renewable Energy Agency (ARENA) via the Australian Centre for Advanced Photovoltaics (ACAP). Facilities at the Australian National Fabrication Facility were used for polycrystalline silicon deposition.