Electrical properties of boron, phosphorus and gallium co-doped silicon

à paraître dans Energy ProcediaInternational audienceA number of ingots were grown from solar grade poly Silicon, to which Boron, Phosphorous and Gallium were added as dopants. The introduction of Gallium as a third dopant allowed for a better control of the resistivity and the doping type during ingot growth. Measured resistivity in this material is shown to be systematically higher than that calculated using Scheil's law for the dopants distribution and Klaassen's model for the majority carrier mobility. This resistivity underestimation is shown to be, at least partially, due to a reduction of the majority carrier mobility in highly compensated Si compared to Klaassen's model. A similar reduction is observed for the minority carrier mo- bility. We propose a correction term in the mobility calculation, to allow a greater accuracy in the prediction of the resistivity and mobility of compensated solar grade silicon

Doping engineering to increase the material yield during crystallization of B and P compensated silicon

International audienceIn this paper, we investigate gallium co-doping during crystallization of boron and phosphorus compensated Si. It is shown that the addition of gallium yields a fully p-type ingot with high resistivity despite high B and P contents in the silicon melt. Segregation of doping impurities is consistent with theory. Minority carrier lifetime and majority carrier mobility measurements indicate that this material is suitable for the realization of solar cells with comparable efficiencies to standard material. Significant light-induced degradation of minority carrier lifetime is however revealed to occur in this material as in standard boron-doped silicon

Ga co-doping in Cz-grown silicon ingots to overcome limitations of B and P compensated silicon feedstock for PV applications

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