Assessment of a low-cost gold-free metallization for III–V high concentrator solar cells

A gold-free metallization is proposed to be used as the grid contact in III–V concentrator solar cells. This metallization is based on the Cu/Ge system which has been reported to attain very low specific contact resistances on n-GaAs. In this letter, we show that metal layers with low resistivity (13 μΩ cm) can be obtained if the copper content in the alloy is around 28% in weight for a wide range of annealing temperatures (400–450 °C). Finally, this metallization has been used to manufacture single-junction GaAs high concentrator solar cells. Efficiencies of 26.2% at 1000 suns have been reached.