SEQUENTIAL SILICON SURFACE MELTING AND ATMOSPHERIC PRESSURE PHOSPHORUS DOPING FOR CRYSTALLINE TUNNEL JUNCTION FORMATION IN SILICON/PEROVSKITE TANDEM SOLAR CELLS

摘要

In monolithically integrated 2-terminal silicon/perovskite tandem solar cells, one of the critical steps is the formation of the layer(s) that interconnects the two sub-cells. Of the range of possibilities for monolithic integration, crystalline silicon tunnel junctions are a potential candidate. The crystalline tunnel junction has the advantage of transparency whilst also withstanding high temperature steps which may be required to form the perovskite sub-cell on top of the silicon sub-cell. Here, we present our recent scalable setup that has its core based on the gas immersion laser doping technique (GILD). We have adapted it to reach high speed rastering of the laser spot over large areas to dope silicon wafers with the aim of forming a tunnel junction, i.e. shallow doping with an abrupt doping profile. Morphological analysis of the laser processed samples after parameters tuning has resulted in the unequivocal shallow melting while faceted structures are left to solidify on the surface. Shallow phosphorus depth profiles (< 1 μm) with an abrupt concentration drop were also measured in the processed samples. We observed that the number of scans has a predominate impact on the profiles' form.