Point-Contacting by Localized Dielectric Breakdown With Breakdown Fields Described by the Weibull Distribution

We report on the point-contacting by localized dielectric breakdown (PLDB) technique applied to form ohmic contacts at room temperature, to silicon test structures with locally doped surface regions and four dielectrics commonly used for surface passivation in silicon solar cells. Our results show that the statistical distribution of the electric field at breakdown for these samples can be fitted with a Weibull distribution, indicating that a percolation model used for dielectric failure can be used to describe this process. Poole-Frenkel field-assisted hopping conduction was identified as being the dominant conduction mechanism for all of the passivating layers, however, no correlation between leakage current and breakdown field was observed. Despite the lack of a predictive model for the breakdown field, the PLDB technique can be applied to structures with a number of different dielectric layers, delivering a low-resistance ohmic contact without the need for high-temperature processing steps.