GaAs on Ge cell and panel technology for advanced space flight application

Tandem junction GaAs/Ge solar cells measuring 2-cm*2-cm were fabricated with efficiencies up to 18.2% (AM0, 28 degrees C) using in-house grown material. Previously, an efficiency of 21.7% (AM0, 25 degrees C) was demonstrated. Welded tab pull strengths greater than 3.3 N (340 gms) were achieved with no electrical degradation or mechanical damage for both the front and back contacts. A panel incorporating GaAs/Ge cells was built to demonstrate this assembly technology. Modeling shows that with proper design, the thin dual-junction GaAs/Ge cells can be made with efficiencies of 24% (AM0, 28 degrees C) by improving optical coatings and reducing the effect of interface and back surface recombination.<>