- Title
- Calcium contacts to n-type crystalline silicon solar cells
- Creator
- Allen, Thomas G.; Bullock, James; Zheng, Peiting; Vaughan, Ben; Barr, Matthew; Wan, Yimao; Samundsett, Christian; Walter, Daniel; Javey, Ali; Cuevas, Andres
- Relation
- Progress in Photovoltaics Vol. 25, Issue 7, p. 636-644
- Publisher Link
- http://dx.doi.org/10.1002/pip.2838
- Publisher
- John Wiley & Sons
- Resource Type
- journal article
- Date
- 2017
- Description
- Direct metallization of lightly doped n-type crystalline silicon (c-Si) is known to routinely produce non-Ohmic (rectifying) contact behaviour. This has inhibited the development of n-type c-Si solar cells with partial rear contacts, an increasingly popular cell design for high performance p-type c-Si solar cells. In this contribution we demonstrate that low resistance Ohmic contact to n-type c-Si wafers can be achieved by incorporating a thin layer of the low work function metal calcium (ϕ ~2.9 eV) between the silicon surface and an overlying aluminium capping layer. Using this approach, contact resistivities of ρc ~ 2 mΩcm2 can be realised on undiffused n-type silicon, thus enabling partial rear contacts cell designs on n-type silicon without the need for a phosphorus diffusion. Integrating the Ca/Al stack into a partial rear contact solar cell architecture fabricated on a lightly doped (ND = 4.5 × 1014 cm−3) n-type wafer resulted in a device efficiency of η = 17.6% where the Ca/Al contact comprised only ~1.26% of the rear surface. We demonstrate an improvement in this cell structure to an efficiency of η = 20.3% by simply increasing the wafer doping by an order of magnitude to ND = 5.4 × 1015 cm−3.
- Subject
- partial rear contacts; dopant-free contacts; calcium; work function; barrier height; contact resistance
- Identifier
- http://hdl.handle.net/1959.13/1355115
- Identifier
- uon:31417
- Identifier
- ISSN:1062-7995
- Language
- eng
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