Electron-beam-induced current study of hydrogen passivation on grain boundaries in multicrystalline silicon: Influence of GB character and impurity contamination

The impacts of grain boundary (GB) character and impurity contamination level on the hydrogen passivation of GBs in multicrystalline silicon (mc-Si) were studied by means of an electron-beam-induced current (EBIC) technique. In mc-Si with a low contamination of Fe, the 300 K EBIC contrast of all kinds of GBs in the H-passivated state was weak and similar to that in the as-grown state. The 100 K EBIC contrast of Σ (Σ=3, 9, and 27) GBs decreased about 75-80%, whereas that of random and small-angle GBs decreased about 35-40%. Due to the different impurity gettering ability of different GBs, the variation in 100 K EBIC contrast has suggested that the effect of H-passivation depends on both the GB character and impurity contamination level. In the mc-Si with heavy contamination of Fe, at both 300 and 100 K, the EBIC contrast of both Σ (Σ=3) and random GBs decreased but the ratio was <40%, suggesting that the H-passivation is mainly affected by the impurity contamination level.