Black silicon with tunnel oxide passivated contacts

Maren E. Kloster, Maria-Louise Witthøft, Denver C. Shearer, Alireza Hajijafarassar, Rasmus S. Davidsen, Dirch H. Petersen, Ole Hansen, Beniamino Iandolo

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    We investigate surfaces of black silicon (bSi) fabricated by reactive ion etch (RIE) on n-type Si substrates and passivated by in-situ doped polycrystalline Si (poly-Si) deposited by low pressure chemical vapor deposition (LPCVD). We achieved full surface coverage of bSi surfaces for poly-Si thickness of 20 nm. We determined sheet resistance on p-type and n-type poly-Si by means of micro four-point probe measurements. Effective lifetime mapping on symmetrically passivated samples shows that n-type poly-Si offers excellent surface passivation after hydrogenation, reaching effective lifetime values of almost 4 ms on non-textured substrates. P-type poly-Si shows values of effective lifetime lower than 800 μs and requires further improvement. We calculated i-Voc of up to 711 mV and 609 mV for asymmetrically passivated lifetime samples without texturing and with bSi, respectively. The effective lifetime is limited by the less-than-optimal passivation of the p-type poly-Si. Preliminary solar cell measurements indicate that both cell voltage and fill factor require major improvement on textured surfaces. Current work is directed towards the following goals: improving the quality of the p-type poly-Si; testing possible replacement of wet chemistry to grow the tunnel oxide using dry furnace oxidation; fabricating and comparing cells with p-n junction at the front or at the bottom of the cell.
    Original languageEnglish
    Title of host publicationProceedings of the 35th European Photovoltaic Solar Energy Conference and Exhibition
    Publication date2018
    ISBN (Electronic)3-936338-50-7
    Publication statusPublished - 2018
    Event35th European Photovoltaic Solar Energy Conference and Exhibition - Brussels, Belgium
    Duration: 24 Sept 201828 Sept 2018


    Conference35th European Photovoltaic Solar Energy Conference and Exhibition


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