Laser fired contact for n-type crystalline Si solar cell

Ohmic contacts to n-type crystalline silicon created by local laser firing was studied in this paper. A novel metal stack of Al-Sb-Ti was fired through a dielectric layer or opposite doped amorphous silicon layer. Specific contact resistances of less than 1.9 mΩcm² and 0.31 mΩcm² using a pseudo transfer length method and a vertical test structure, respectively, are demonstrated. Recombination loss due to laser damage was consistent with an extracted local Surface Recombination Velocity (SRV) ~20,000 cm/s similar to values for laser fired base contact for p-type crystalline silicon. Hetero-junction devices were fabricated with laser fired back contact and proof-of-concept efficiencies of 14.4% on front silicon hetero-junction and 13.1% on interdigitated back contact silicon hetero-junction (IBC-SHJ) cells were achieved. This localized base contact technique will enable low cost back contact patterning and innovative design for n type crystalline solar cells.