ENHANCEMENT OF DIFFUSION LENGTH OF PREGETTERED MULTICRYSTALLINE SILICON SOLAR-CELLS BY HYDROGEN-ION IMPLANTATION AT THE END OF THE PROCESS

2 X 2 cm2 n+pp+ multicrystalline silicon solar cells have been fabrica ted using thin wafers less than 200 mum thick. A large electron diffus ion length has been achieved in these wafers after metallic impurity g ettering using a heavy phosphorus diffusion prior to cell processing. Further improvements in the electron diffusion length (L(n)) and in th e short circuit current (J(sc)) of these cells are brought out by hydr ogen ion implantation carried out through the back surface of the fini shed cell. A 25% increase in L(n) and a 5.5% increase in J(sc) are obt ained.