Surface damage caused by electron-beam metallization of high open-circuit voltage solar cells

Metallization of high open-circuit voltage metal-insulator n-type-p-type(MINP)solar cells using an electron-beam deposition apparatus has been observed to cause degradation of device performance. Investigations using metal-insulator-semiconductor (MIS) diodes as test devices showed that the damage is consistent with a massive increase in surface-state density, and may be due to both radiation and the impact of charged particles. The damage can be eliminated by resistive evaporation of 100 nm of metal prior to use of the electron beam. It is likely that use of an electron beam to deposit grid lines and antireflection coatings on any high open-circuit voltage solar cell will lead to irreversible degradation in performance.