Ab-initio calculation study on the formation mechanism of boron-oxygen complexes in c-Si

Boron-oxygen (B-O) complex in crystalline silicon (c-Si) solar cells is responsible for the light-induced efficiency degradation of solar cell. However, the formation mechanism of B-O complex is not clear yet. By Ab-initio calculation, it is found that the stagger-type oxygen dimer (O2ist) should be the component of B-O complex, whose movement occurs through its structure reconfiguration at low temperature, instead of its long-distance diffusion. The O2ist can form two stable “latent centers” with the Bs, which are recombination-inactive. The latent centers can be evolved into the metastable recombination centers via their structure transformation in the presence of excess carriers. These results can well explain the formation behaviors of B-O complexes in c-Si.