Localized ohmic contact through a passivation dielectric for novel rear surface design solar cells

We report on the demonstration of a method of forming localized ohmic contact through a-Si passivation dielectric to an underlying laser doped region. The test device consists of a metal-insulator-semiconductor (MIS) device containing a single laser doped point contact. By applying a voltage to the gate of the MIS structure, dielectric breakdown occurs to the dielectric but is self-aligned and limited to the region directly over the doped region. This leads to an ohmic contact with low specific contact resistance while preserving the surface passivation properties of the adjacent a-Si dielectric.