A very low resistance, non-sintered contact system for use on indium phosphide concentrator/shallow junction solar cells

The possibility of providing low-resistance contacts to shallow-junction InP solar cells which do not require sintering and which do not cause device degradation even when subjected to extended annealing at elevated temperatures is investigated. It is shown that the addition of In to Au contacts in amounts that exceed the solid solubility limit lowers the as-fabricated (unsintered) contact resistivity R_c to the 10^-5 ohm-cm² range. Consideration is also given to the contact system Au/Au ₂P₃ which has been shown to exhibit as-fabricated R_c values in the 10^-6 ohm-cm² range, but which fails quickly when heated. It is shown that the substitution of a refractory metal (W, Ta) for Au preserves the low R_c values while preventing the destructive reactions that would normally take place in this system at high temperatures