Optimized device design for radiation resistant and high dislocation solar cells for space

Electron and proton-induced point defects as well as extended crystalline defects (e.g. dislocations or grain boundaries) cause reduction of minority carrier diffusion length which in turn results in solar cell efficiency degradation. For hetero-epitaxial or metamorphic III-V devices dislocation densities have to be below 10⁶ cm^-2 to obtain highest BOL efficiencies, yet EOL efficiency optimization, which favors thinner cell designs, synergistically yield to more defect tolerant devices. In this work and within the framework of the GaAs-archetype solar cell material system we have computed the efficiencies as function of the combined effect of dislocation densities, radiation doses (1 MeV equivalent electrons) and device emitter and base design (doping-thickness) and show that by implementing an appropriate design EOL efficiencies for highly dislocated devices can be significantly improved over that of a conventionally designed state of the art defect free device.