Platinum-diffusion: a method for the determination of vacancy profiles in EFG silicon

Platinum diffusion is a convenient method to monitor vacancy profiles in silicon. We have applied this method for the determination of vacancy profiles of Edge-defined Film-fed Growth (EFG) silicon prior to and subsequent to the fabrication of Al-alloyed backside contacts. Based on our results, it turns out that there is no indication for the formation or annihilation of vacancies caused by the Al-alloying process. Compared to multicrystalline Baysix /sup /spl reg//silicon ([Vac]<5/spl times/10/sup 11/ cm/sup -3/), tri-crystalline Si (TriSi) ([Vac]/spl cong/3/spl times/10/sup 12/ cm/sup -3/) and Cz-Si ([Vac]=10/sup 11/cm/sup -3/-10/sup 12/ cm/sup -3/), the vacancy concentration is higher in EFG silicon ([Vac]/spl cong/(1-2)/spl times/10/sup 13/ cm/sup -3/). Assuming that vacancies can dissociate hydrogen molecules as proposed in the literature, the relatively high vacancy concentration in EFG silicon may be responsible for the fast and effective hydrogen passivation of EFG silicon.