Thin GaAs Solar Cells For High Irradiation Levels
Sergey Maximenko1, Matt Lumb2, Jim Moore2, Loise Hirst3, Mike Yakes1, Philip Jenkins1
1US Naval Research Laboratory, Washington, DC, United States
/2The George Washington University, Washington, DC, United States
/3University of Cambridge, Cambridge, United Kingdom

A simulation of thin, single-junction GaAs solar cells with an active device thickness < 1.6 µm is performed to optimize performance for irradiation levels associated with high energy orbits (1 MeV electrons with a fluence of 1E15 e-/cm2). This is done through the optimization of the emitter and base parameters, such as doping concentration and device thickness. Conventional n-emitter/p-base and p-emitter/n-base configurations are considered as well as rear junction (thick emitter) structures with a backside gold reflective coating. The extended Hovel model with photon recycling effects is used for device simulation. The analysis shows that the conventional n-emitter/p-base design with a base thickness ~0.6 µm and doping levels above 1E18 cm-3 is the best design to provide the highest end of life specific power with power degradation at < 6%. N-emitter/p-base ultrathin solar cells (< 600 nm) with heavily doped absorbers ~5E18 [cm-3] are the most radiation tolerant designs with power degradation at < 3%.