Suitability of Ti and Ni as diffusion barriers for III-V space solar cells

Experiments were performed in order to explore the potential of Ti and Ni as Cu diffusion barriers for III-V solar cells. Accelerated life testing with solar cells with 10 or 100nm thick Ti and Ni barriers at 300° C indicates that 10nm thick barriers show a better performance compared to 100nm thick barriers, but further experiments at a lower temperature are required to validate this conclusion. Accelerated life testing at 250° C with solar cells with various front contacts containing a Ti or Ni barrier shows that cells with Au/Ti/Cu, Ni/Cu and Au/Ni/Cu have a performance better than cells with Au/Cu contacts. The Au/Ti/Cu contact scheme appears to be most promising as cells with this contact scheme show degradation behaviour similar to that of cells with plain Au contacts.