The design, qualification and use of bypass diode integration onto GaAs/Ge solar cells

Abstract

Bypass diodes are integrated onto GaAs/Ge solar cells by selectively thinning a pocket into the backside of the solar cell's germanium substrate, electrically connecting the two devices via insulated metal foil tabs (Ag, Ag/Kovar or Ag/Mo) attached by thermal compression bonding (welding) and/or soldering and bonding the 3 mm thick silicon diode chip into the germanium pocket with a standard space qualified adhesive. This efficient and synergistic method of integration maintains the modularity of the solar cell unit, minimizes active area obscuration, heat sinks the diode and eliminates the need for discrete bypass diode wiring at the solar panel level. The approach is also applicable to future high efficiency, multijunction solar cells. Qualification status, performance results and manufacturing capabilities are discussed.