Minority carrier lifetime improvement in p-type silicon by oxygen related centers gettering at low temperatures: application to the heterojunction solar cell processing

The minority carrier lifetime improvement after thermal heating of different p-type Si substrates at /spl les/650/spl deg/C is studied as an initial technological step for heterojunction solar (HJ) cells processing. It is found that the effective lifetime in silicon substrates is essentially controlled by the oxygen and hydrogen-related centers. It is supposed that the observed enhancement of the effective lifetime in p-type substrates at heat treatments below 650/spl deg/C can be attributed to the hydrogen release from oxygen-related centers and to the gettering of impurities by the oxygen-related centers. An efficient application of the observed phenomena for heterojunction ITO/(n)a-Si:H/(p)c-Si solar cell processing is demonstrated for a middle level quality Cz Si substrates were the lifetime improved by the heat treatment.