Latent complexes of interstitial boron and oxygen dimers as a reason for degradation of silicon-based solar cells

Abstract

Reduction in electron lifetime induced by excess electrons is a key effect in degradation of solar cells based on boron-doped and oxygen-containing silicon. Although boron related, degradation is controlled by the concentration of holes and not by the boron concentration. This recent finding is the basis for a new degradation model in which the degradation starts from a latent complex BiO2 of an interstitial boron atom and an oxygen dimer. Electron-induced reconstruction of this defect results in a production of recombination centers. This model provides a detailed explanation of the basic features of the degradation, and of subsequent recovery by annealing in the dark.