Electron irradiated LPE grown AlGaAs/GaAs tandem solar cells

摘要

Effect of irradiation on the LPE-grown Al sub 0.35 Ga SUB 0.65 As/GaAs monolithic tandem solar cells have been studied. Electron beam induced current method was used for investigation of the minority carrier diffusion length degradation after electron irradiation. The L sub p value of 18 mum in undoped n-GaAs was obtained before irradiation. The EOL L sub p=4 mum was obtained after 3.75 MeV electron irradiation to a fluence of 3*10 sup 15 cm sup -2. A low radiation damage coefficient K sub L=2*10 sup -9 has been extracted through these experiments. The optimum p-Al sub 0.35Ga sub 0.65 As layer thickness of 0.3-0.5 mum ensures the best radiation resistance of the top Al sub 0.35 Ga sub 0.65As - based subcell. The optimum p-GaAs emitter layer thickness of 0.3 mum and the minimum doping level in n-GaAs base are the conditions for the best radiation resistance of the bottom GaAs subcell. The remaining factors of photocurrent I sub SC/I sub SCO=0.87 and of efficiency P sub max/P sub 0=0.71 have been obtained in the bottom cells based on undoped GaAs after 3.75 MeV electron irradiation at displacement damage dose of 2*10 sup 11 MeV/g.